DIYstompboxes wiki - User contributions [en]

Safety

2006-12-01T06:34:16Z

Idlechatterbox: /* '''Odds & Ends''' */

[formatting not done yet]

== Electrocution ==

This little section of the Wiki can’t replace common sense, knowledge, and a healthy respect for the hazards we may encounter when doing DIY projects. Its intent is to offer you a place to start, to learn more about some of the safety issues you may encounter before you face them. The internet is a great tool to find the answers…please use it! If you’re in doubt about the safety of what you’re about to undertake, please take the time to work into it, learning as you go, and seek the advice of those with more experience. With the proper attitude, this hobby can be fun and rewarding as well as safe! As with all endeavors, putting one’s health and well-being first is the most important thing.

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

In light of that fact, here are a few things that one can do to minimze the risks involved in DIY pedals and related gear.

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly.

Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

== Soldering Hazards ==

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

== '''Safety When Etching Printed Circuit Boards''' ==

When building many DIY projects, it's natural to want to make your own printed circuit board. But this can, not surprisingly, lead to another safety and health issue: the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point those who are interested in safety in the right direction.

The general consensus seems to be this: what we call etchants are in reality acids and they CAN burn you. If this concerns you, and it should, the easiest course would be to simply explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags with you, then by all means proceed with knowledge, caution, and respect!

'''BASIC SAFETY''':
When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry-lab safety practices. For example, always work in a safe place, which is to say one free of obstacles/trip hazards, and one that is also WELL-VENTILATED (e.g., a garage?). A safe place would also be clear of objects that may be ruined by contact with the acid. Wear appropriate (i.e., old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Also, as obvious as it might sound, make sure to keep your face away from the etching container!

Etchants and the metals that they dissolve are poisonous. This means that you should not use containers, utensils, and the like which could be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect that you show towards electricity when you are the presence of liquids that you always would.

Lastly, read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground. Generally speaking, you should keep it out of the trash, since improper disposal could lead to serious environmental clean-up costs, the unintended poisoning of drinking water wells and the like. There are enough challenges in building pedals without trying to do it with the EPA on your case!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. Remember, as with any DIY project, your understanding of the risks that may be present, and having a plan to deal with them, will help ensure your safety as you enjoy this hobby.
----------------------------------------------------------------------
Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride
Material Safety Data Sheet (MSDS)
http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages:
Easy to use, sold in premixed form.
Fairly inexpensive and easy to find.
Does a very good job etching.

Disadvantages:
Can cause chemical burns! See MSDS for other health concerns.
Stains almost everything it comes into contact with.
Will corrode other metals.
The chemicals dark reddish color makes it difficult to check etching progress.

Tips:
Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil!
Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark!
http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more.

The reaction between the acid and the soda produces a foam-like substance which, in turn, dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction expand to occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, you can expect the reaction to cause an overflow of the container, and very likely cover your workspace with ooze within 20 seconds or so. If that doesn't sound bad enough, keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life most anything that it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret.

One thing that increases the hazard level is the fact that the etchant may LOOK completely treated when it isn't. For example, you may have just a small residual film at the bottom of the container, yet when you dump a few tablespoons of soda on it, it might start to foam like crazy. In that case, you will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

== '''Painting Safety''' ==

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

'''Ventilation''': When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

'''Eye protection''': Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

'''Fire Hazards''': Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area, such as a small workshop, to create a combustible atmosphere - remember to ventilate! Also keep in mind that rags soaked in paints and solvents should be spread over a surface, such as a workbench, when you are done, and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

'''Solvents''': It was pretty common in earlier years to clean up equipment and even body parts with solvents such as paint thinner. On one hand, this was always very effective. On the other hand, it’s also provides one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, can cause liver damage, and many are carcinogenic in addition to being highly flammable. You can, in short, find better ways to clean up. Wash with soap and water if you get some on your hands. A good approach would be to save the thinner for cleaning overspray (preferably while wearing gloves), and get one of the citrus-based non-toxic hand cleaners for cleaning any skin.

== '''Odds & Ends''' ==
'''Mercury''': This has come up a couple of times in the forum, so it may be worth mentioning. Position-sensitive switches, such as those found in thermostats, often contain mercury, a poisonous liquid metal. If the glass switch vial breaks, the small quantity of mercury inside can get loose and be tracked everywhere. This is a problem, since, however cool merc might be to look at, the substance is toxic if ingested, and will release poisonous fumes if heated. If a spill happens to you, do not touch the mercury! It can be scooped up with a couple of pieces of cardboard or a dustpan and disposed of properly. The key word here is ''properly''. Don’t casually discard this substance! Here is a link to disposal and other mercury-related information:
http://www.epa.gov/epaoswer/hazwaste/mercury/faq/spills.htm

Remember: Be sure not to touch your mouth before you are able to thoroughly wash up!

'''PCB dust''': When working with printed circuit board material, it may be necessary to cut it to shape. There are many ways to do this (hack saw, Dremel, score-and-snap…), but in all cases one should try to create as little dust as possible during the process. This dust can cause health problems – therefore, a N95 (or better) rated paper-style dust mask should be worn to minimize exposure. And the usual caveat of proper ventilation applies.

'''The other PCBs''' – Polychlorinated Biphenyls: First, the bad news. PCBs are a highly toxic chemical once used as transformer oil and capacitor dielectric before the dangers associated with them were known. Today, these chemicals are considered dangerous enough that their use in industry is outlawed. The good news is that there is a very small – some might say negligable – risk that you may one day encounter PCBs in old equipment. Be aware that they are out there lurking in some old components. Washing up thoroughly after handling parts and avoiding gel or oil-like stuff you might encounter can help keep you safe.

'''Metal ‘dust’''' – When drilling holes in an enclosure, watch out for the shavings. If the particles are just the right size, they could get airborne and be inhaled. A much greater risk is that they’ll be forced into the skin of your fingers and cause discomfort or even splinters, especially if the holes you’ve drilled are rough. Clean them up when you’re done so they don’t spread around your work surface and get into things!

'''Safe cooking''' - A lot of people talk about ‘cooking’ their enclosures once they’ve been painted, to bake the finish on and make it cure faster. Opinions vary on the times and temperatures that this operation should use. A baking temp of 200F for 20-30 mins. seems to be the norm. That might seem like nothing to worry about, especially since a loaf of bread might be baked at 375 for almost an hour (and pizzas are often baked at 500F). But two strong issues arise if you try this at home with your enclosures. First, baking an enclosure can present a respectable fire and/or burn hazard! Second, the fumes released by the process are definitely of a toxic nature. So once more, ventilate, and do your baking outdoors if possible! Best of all would be to never use an oven that will be used for food again – a simple toaster oven dedicated to the purpose can be purchased cheaply.

Safety

2006-12-01T06:26:43Z

Idlechatterbox: /* '''Painting Safety''' */

[formatting not done yet]

== Electrocution ==

This little section of the Wiki can’t replace common sense, knowledge, and a healthy respect for the hazards we may encounter when doing DIY projects. Its intent is to offer you a place to start, to learn more about some of the safety issues you may encounter before you face them. The internet is a great tool to find the answers…please use it! If you’re in doubt about the safety of what you’re about to undertake, please take the time to work into it, learning as you go, and seek the advice of those with more experience. With the proper attitude, this hobby can be fun and rewarding as well as safe! As with all endeavors, putting one’s health and well-being first is the most important thing.

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

In light of that fact, here are a few things that one can do to minimze the risks involved in DIY pedals and related gear.

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly.

Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

== Soldering Hazards ==

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

== '''Safety When Etching Printed Circuit Boards''' ==

When building many DIY projects, it's natural to want to make your own printed circuit board. But this can, not surprisingly, lead to another safety and health issue: the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point those who are interested in safety in the right direction.

The general consensus seems to be this: what we call etchants are in reality acids and they CAN burn you. If this concerns you, and it should, the easiest course would be to simply explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags with you, then by all means proceed with knowledge, caution, and respect!

'''BASIC SAFETY''':
When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry-lab safety practices. For example, always work in a safe place, which is to say one free of obstacles/trip hazards, and one that is also WELL-VENTILATED (e.g., a garage?). A safe place would also be clear of objects that may be ruined by contact with the acid. Wear appropriate (i.e., old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Also, as obvious as it might sound, make sure to keep your face away from the etching container!

Etchants and the metals that they dissolve are poisonous. This means that you should not use containers, utensils, and the like which could be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect that you show towards electricity when you are the presence of liquids that you always would.

Lastly, read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground. Generally speaking, you should keep it out of the trash, since improper disposal could lead to serious environmental clean-up costs, the unintended poisoning of drinking water wells and the like. There are enough challenges in building pedals without trying to do it with the EPA on your case!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. Remember, as with any DIY project, your understanding of the risks that may be present, and having a plan to deal with them, will help ensure your safety as you enjoy this hobby.
----------------------------------------------------------------------
Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride
Material Safety Data Sheet (MSDS)
http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages:
Easy to use, sold in premixed form.
Fairly inexpensive and easy to find.
Does a very good job etching.

Disadvantages:
Can cause chemical burns! See MSDS for other health concerns.
Stains almost everything it comes into contact with.
Will corrode other metals.
The chemicals dark reddish color makes it difficult to check etching progress.

Tips:
Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil!
Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark!
http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more.

The reaction between the acid and the soda produces a foam-like substance which, in turn, dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction expand to occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, you can expect the reaction to cause an overflow of the container, and very likely cover your workspace with ooze within 20 seconds or so. If that doesn't sound bad enough, keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life most anything that it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret.

One thing that increases the hazard level is the fact that the etchant may LOOK completely treated when it isn't. For example, you may have just a small residual film at the bottom of the container, yet when you dump a few tablespoons of soda on it, it might start to foam like crazy. In that case, you will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

== '''Painting Safety''' ==

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

'''Ventilation''': When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

'''Eye protection''': Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

'''Fire Hazards''': Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area, such as a small workshop, to create a combustible atmosphere - remember to ventilate! Also keep in mind that rags soaked in paints and solvents should be spread over a surface, such as a workbench, when you are done, and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

'''Solvents''': It was pretty common in earlier years to clean up equipment and even body parts with solvents such as paint thinner. On one hand, this was always very effective. On the other hand, it’s also provides one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, can cause liver damage, and many are carcinogenic in addition to being highly flammable. You can, in short, find better ways to clean up. Wash with soap and water if you get some on your hands. A good approach would be to save the thinner for cleaning overspray (preferably while wearing gloves), and get one of the citrus-based non-toxic hand cleaners for cleaning any skin.

== '''Odds & Ends''' ==
'''Mercury''': This has come up a couple of times in the forum, so it may be worth mentioning. Position-sensitive switches, such as those found in thermostats, often contain mercury, a poisonous liquid metal. If the glass switch vial breaks, the small quantity of mercury inside can get loose and be tracked everywhere. The substance is toxic if ingested, and will release poisonous fumes if heated. If a spill happens to you, do not touch the mercury! It can be scooped up with a couple of pieces of cardboard or a dustpan and disposed of properly. Don’t casually discard this substance! Be sure not to touch your mouth before you are able to thoroughly wash up! Here is a link to disposal and other mercury-related information:
http://www.epa.gov/epaoswer/hazwaste/mercury/faq/spills.htm

'''PCB dust''': When working with printed circuit board material, it may be necessary to cut it to shape. There are many ways to do this (hack saw, Dremel, score-and-snap…), but in all cases one should try to create as little dust as possible during the process. This dust can cause health problems – therefore, a N95 (or better) rated paper-style dust mask should be worn to minimize exposure. And the usual caveat of proper ventilation applies.

'''The other PCBs''' – Polychlorinated Biphenyls: PCBs are a highly toxic chemical once used as transformer oil and capacitor dielectric before the dangers associated with them were known. Today, these chemicals are outlawed. There is a very small – some might say negligable – risk that you may one day encounter PCBs in old equipment. Be aware that they are out there lurking in some old components. Washing up thoroughly after handling parts and avoiding gel or oil-like stuff you might encounter can help keep you safe.

'''Metal ‘dust’''' – When drilling holes in an enclosure, watch out for the shavings. If the particles are just the right size, they could get airborne and be inhaled. A much greater risk is that they’ll be forced into the skin of your fingers and cause discomfort or even splinters, especially if the holes you’ve drilled are rough. Clean them up when you’re done so they don’t spread around your work surface and get into things!

'''Safe cooking''' - A lot of people talk about ‘cooking’ their enclosures once they’ve been painted, to bake the finish on and make it cure faster. Opinions vary on the times and temperatures that this operation should use….200F for 20-30 mins. seems to be the norm. Two strong issues arise if you try this at home. Baking an enclosure can present a respectable fire and/or burn hazard! And the fumes released by the process are definitely of a toxic nature. So, ventilate, and do this outdoors! And don’t use an oven that will ever be used for food again – a simple toaster oven dedicated to the purpose can be purchased cheaply.

Safety

2006-12-01T06:21:59Z

Idlechatterbox: /* '''Safety When Etching Printed Circuit Boards''' */

[formatting not done yet]

== Electrocution ==

This little section of the Wiki can’t replace common sense, knowledge, and a healthy respect for the hazards we may encounter when doing DIY projects. Its intent is to offer you a place to start, to learn more about some of the safety issues you may encounter before you face them. The internet is a great tool to find the answers…please use it! If you’re in doubt about the safety of what you’re about to undertake, please take the time to work into it, learning as you go, and seek the advice of those with more experience. With the proper attitude, this hobby can be fun and rewarding as well as safe! As with all endeavors, putting one’s health and well-being first is the most important thing.

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

In light of that fact, here are a few things that one can do to minimze the risks involved in DIY pedals and related gear.

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly.

Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

== Soldering Hazards ==

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

== '''Safety When Etching Printed Circuit Boards''' ==

When building many DIY projects, it's natural to want to make your own printed circuit board. But this can, not surprisingly, lead to another safety and health issue: the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point those who are interested in safety in the right direction.

The general consensus seems to be this: what we call etchants are in reality acids and they CAN burn you. If this concerns you, and it should, the easiest course would be to simply explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags with you, then by all means proceed with knowledge, caution, and respect!

'''BASIC SAFETY''':
When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry-lab safety practices. For example, always work in a safe place, which is to say one free of obstacles/trip hazards, and one that is also WELL-VENTILATED (e.g., a garage?). A safe place would also be clear of objects that may be ruined by contact with the acid. Wear appropriate (i.e., old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Also, as obvious as it might sound, make sure to keep your face away from the etching container!

Etchants and the metals that they dissolve are poisonous. This means that you should not use containers, utensils, and the like which could be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect that you show towards electricity when you are the presence of liquids that you always would.

Lastly, read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground. Generally speaking, you should keep it out of the trash, since improper disposal could lead to serious environmental clean-up costs, the unintended poisoning of drinking water wells and the like. There are enough challenges in building pedals without trying to do it with the EPA on your case!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. Remember, as with any DIY project, your understanding of the risks that may be present, and having a plan to deal with them, will help ensure your safety as you enjoy this hobby.
----------------------------------------------------------------------
Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride
Material Safety Data Sheet (MSDS)
http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages:
Easy to use, sold in premixed form.
Fairly inexpensive and easy to find.
Does a very good job etching.

Disadvantages:
Can cause chemical burns! See MSDS for other health concerns.
Stains almost everything it comes into contact with.
Will corrode other metals.
The chemicals dark reddish color makes it difficult to check etching progress.

Tips:
Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil!
Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark!
http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more.

The reaction between the acid and the soda produces a foam-like substance which, in turn, dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction expand to occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, you can expect the reaction to cause an overflow of the container, and very likely cover your workspace with ooze within 20 seconds or so. If that doesn't sound bad enough, keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life most anything that it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret.

One thing that increases the hazard level is the fact that the etchant may LOOK completely treated when it isn't. For example, you may have just a small residual film at the bottom of the container, yet when you dump a few tablespoons of soda on it, it might start to foam like crazy. In that case, you will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

== '''Painting Safety''' ==

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

'''Ventilation''': When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

'''Eye protection''': Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

'''Fire Hazards''': Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area to create a combustible atmosphere - remember to ventilate! Rags soaked in paints and solvents should be spread over a surface such as a workbench and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

'''Solvents''': It was pretty common in earlier years to clean up with solvents such as paint thinner. This is very effective, but it’s also one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, leads to liver damage and can be carcinogenic, and is also highly flammable. Wash with soap and water if you get some on your hands. Save the thinner for cleaning overspray…get one of the citrus-based non-toxic hand cleaners for cleaning skin.

== '''Odds & Ends''' ==
'''Mercury''': This has come up a couple of times in the forum, so it may be worth mentioning. Position-sensitive switches, such as those found in thermostats, often contain mercury, a poisonous liquid metal. If the glass switch vial breaks, the small quantity of mercury inside can get loose and be tracked everywhere. The substance is toxic if ingested, and will release poisonous fumes if heated. If a spill happens to you, do not touch the mercury! It can be scooped up with a couple of pieces of cardboard or a dustpan and disposed of properly. Don’t casually discard this substance! Be sure not to touch your mouth before you are able to thoroughly wash up! Here is a link to disposal and other mercury-related information:
http://www.epa.gov/epaoswer/hazwaste/mercury/faq/spills.htm

'''PCB dust''': When working with printed circuit board material, it may be necessary to cut it to shape. There are many ways to do this (hack saw, Dremel, score-and-snap…), but in all cases one should try to create as little dust as possible during the process. This dust can cause health problems – therefore, a N95 (or better) rated paper-style dust mask should be worn to minimize exposure. And the usual caveat of proper ventilation applies.

'''The other PCBs''' – Polychlorinated Biphenyls: PCBs are a highly toxic chemical once used as transformer oil and capacitor dielectric before the dangers associated with them were known. Today, these chemicals are outlawed. There is a very small – some might say negligable – risk that you may one day encounter PCBs in old equipment. Be aware that they are out there lurking in some old components. Washing up thoroughly after handling parts and avoiding gel or oil-like stuff you might encounter can help keep you safe.

'''Metal ‘dust’''' – When drilling holes in an enclosure, watch out for the shavings. If the particles are just the right size, they could get airborne and be inhaled. A much greater risk is that they’ll be forced into the skin of your fingers and cause discomfort or even splinters, especially if the holes you’ve drilled are rough. Clean them up when you’re done so they don’t spread around your work surface and get into things!

'''Safe cooking''' - A lot of people talk about ‘cooking’ their enclosures once they’ve been painted, to bake the finish on and make it cure faster. Opinions vary on the times and temperatures that this operation should use….200F for 20-30 mins. seems to be the norm. Two strong issues arise if you try this at home. Baking an enclosure can present a respectable fire and/or burn hazard! And the fumes released by the process are definitely of a toxic nature. So, ventilate, and do this outdoors! And don’t use an oven that will ever be used for food again – a simple toaster oven dedicated to the purpose can be purchased cheaply.

Safety

2006-12-01T05:56:45Z

Idlechatterbox: /* '''Common Risks and Common Warnings''' */

[formatting not done yet]

== Electrocution ==

This little section of the Wiki can’t replace common sense, knowledge, and a healthy respect for the hazards we may encounter when doing DIY projects. Its intent is to offer you a place to start, to learn more about some of the safety issues you may encounter before you face them. The internet is a great tool to find the answers…please use it! If you’re in doubt about the safety of what you’re about to undertake, please take the time to work into it, learning as you go, and seek the advice of those with more experience. With the proper attitude, this hobby can be fun and rewarding as well as safe! As with all endeavors, putting one’s health and well-being first is the most important thing.

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

In light of that fact, here are a few things that one can do to minimze the risks involved in DIY pedals and related gear.

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly.

Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

== Soldering Hazards ==

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

== '''Safety When Etching Printed Circuit Boards''' ==

When building many DIY projects, you might want to make your own printed circuit board. This leads to another safety and health issue…the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point you in the right direction to keep you safe.

The general consensus seems to be: if you are concerned about using etchants, which are acids and CAN burn you, you might want to explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags, then proceed with knowledge, caution, and respect!

'''BASIC SAFETY''':
When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry lab safety practices. Always work in a safe place free of obstacles/trip hazards that is WELL-VENTILATED (garage?), clear of objects that may be ruined by contact with the acid. Wear appropriate (old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Keep your face away from the etching container! Etchants and the metals that dissolve into them are poisonous: do not use containers, utensils and the like which will be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect for electricity in the presence of liquids that you always would.

Read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground, and keep it out of the trash…improper disposal could lead to serious environmental clean-up costs, unintended poisoning of driking water wells and the like!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. As with any DIY project, understanding what risks are present and having a plan to deal with them will help to ensure your safety and health as you enjoy this hobby.
----------------------------------------------------------------------
Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride
Material Safety Data Sheet (MSDS)
http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages:
Easy to use, sold in premixed form.
Fairly inexpensive and easy to find.
Does a very good job etching.

Disadvantages:
Can cause chemical burns! See MSDS for other health concerns.
Stains almost everything it comes into contact with.
Will corrode other metals.
The chemicals dark reddish color makes it difficult to check etching progress.

Tips:
Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil!
Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark!
http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more
The reaction results in a foam-like substance being produced which dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, the reaction will overflow the container and cover your counter with ooze within 20 seconds or so. Keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life anything it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret.
The thing about the etchant is that it may LOOK completely treated when it isn't. You may have just a small residual film at the bottom of the container, and when you dump a few tablespoons of soda on it, it starts foaming like crazy. You will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

== '''Painting Safety''' ==

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

'''Ventilation''': When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

'''Eye protection''': Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

'''Fire Hazards''': Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area to create a combustible atmosphere - remember to ventilate! Rags soaked in paints and solvents should be spread over a surface such as a workbench and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

'''Solvents''': It was pretty common in earlier years to clean up with solvents such as paint thinner. This is very effective, but it’s also one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, leads to liver damage and can be carcinogenic, and is also highly flammable. Wash with soap and water if you get some on your hands. Save the thinner for cleaning overspray…get one of the citrus-based non-toxic hand cleaners for cleaning skin.

== '''Odds & Ends''' ==
'''Mercury''': This has come up a couple of times in the forum, so it may be worth mentioning. Position-sensitive switches, such as those found in thermostats, often contain mercury, a poisonous liquid metal. If the glass switch vial breaks, the small quantity of mercury inside can get loose and be tracked everywhere. The substance is toxic if ingested, and will release poisonous fumes if heated. If a spill happens to you, do not touch the mercury! It can be scooped up with a couple of pieces of cardboard or a dustpan and disposed of properly. Don’t casually discard this substance! Be sure not to touch your mouth before you are able to thoroughly wash up! Here is a link to disposal and other mercury-related information:
http://www.epa.gov/epaoswer/hazwaste/mercury/faq/spills.htm

'''PCB dust''': When working with printed circuit board material, it may be necessary to cut it to shape. There are many ways to do this (hack saw, Dremel, score-and-snap…), but in all cases one should try to create as little dust as possible during the process. This dust can cause health problems – therefore, a N95 (or better) rated paper-style dust mask should be worn to minimize exposure. And the usual caveat of proper ventilation applies.

'''The other PCBs''' – Polychlorinated Biphenyls: PCBs are a highly toxic chemical once used as transformer oil and capacitor dielectric before the dangers associated with them were known. Today, these chemicals are outlawed. There is a very small – some might say negligable – risk that you may one day encounter PCBs in old equipment. Be aware that they are out there lurking in some old components. Washing up thoroughly after handling parts and avoiding gel or oil-like stuff you might encounter can help keep you safe.

'''Metal ‘dust’''' – When drilling holes in an enclosure, watch out for the shavings. If the particles are just the right size, they could get airborne and be inhaled. A much greater risk is that they’ll be forced into the skin of your fingers and cause discomfort or even splinters, especially if the holes you’ve drilled are rough. Clean them up when you’re done so they don’t spread around your work surface and get into things!

'''Safe cooking''' - A lot of people talk about ‘cooking’ their enclosures once they’ve been painted, to bake the finish on and make it cure faster. Opinions vary on the times and temperatures that this operation should use….200F for 20-30 mins. seems to be the norm. Two strong issues arise if you try this at home. Baking an enclosure can present a respectable fire and/or burn hazard! And the fumes released by the process are definitely of a toxic nature. So, ventilate, and do this outdoors! And don’t use an oven that will ever be used for food again – a simple toaster oven dedicated to the purpose can be purchased cheaply.

Safety

2006-11-24T23:45:29Z

Idlechatterbox: /* Soldering Hazards */

[formatting not done yet]

== Electrocution ==

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly. Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

== Soldering Hazards ==

I know, I know…we’ve all soldered 100’s of times, and nothing went wrong. But it can’t hurt to take a few minutes to read this, and make sure we’re not missing anything, can it? Aside from the obvious (and very real) fire hazards posed by a hot soldering iron, there can be a couple of other items we don’t think much about that could pose safety issues. For instance, while the concentrations of dangerous compounds we’re likely to encounter in the DIY world are usually not high, the name of the game is to avoid cumulative exposures. Just as smoking one cigarette isn't likely to cause a whole lot of damage, repeatedly doing so can lead to serious health consequences.

Solder contains lead, and usually has a rosin core that cleans and prepares the surfaces to be joined. Exposure to excessive levels of lead can cause neurologic and reproductive damage. On one hand, then, it is lucky for us that the amounts of lead commonly encountered while building DIY equipment are not high. On the other hand, since the best exposure where lead is concerned is none at all, some caution is in order.

What steps can one take? The basic rules for handling solder are to avoid touching your mouth, other people, eating/drinking/smoking after contact, or otherwise ingesting the stuff. The most likely way to absorb lead from solder is from unintentional ingestion. When you’re done soldering, or you just decide to take a break, wash your hands! Not only will this keep the lead from entering your body, it will keep any traces off of those that you touch. Also, it makes sense to clean up your solder bits at your workstation, and avoid tracking them all over the house ;o)

The second hazard posed by solder is the fumes that are released on contact with a hot iron. These fumes can contain gaseous lead and formaldehyde, as well as anything else that may be present in the rosin. Again, while there is no clear evidence concerning just how much of the nasty substances ar present in the fumes, the simplest way to minimize any risks would be to run a small fan and blow the stuff away from your face. If nothing else, this will essentially dilute the concentration of the hazardous stuff that you may be exposed to. Take a tip from the pros who work in respirators all day: if you can smell the fumes, you’re inhaling them!

And finally, to restate the obvious…probably the highest danger associated with soldering is the hot iron itself. Be sure that it’s in good condition, with no damaged insulation, etc. And how many of us have accidentally left the thing on overnight (or for days)? Workstations can be purchased or built that operate on a timer, which will automatically turn the iron off after a specified time period. But one shouldn’t rely totally on a ‘dummy system’; don’t walk away from a hot iron, and be sure it’s off after a soldering session! If you really want to minimize your risks, make a habit of unplugging the cord.

An article can’t replace common sense at the workstation, and this one isn’t meant to be “the last word” on soldering safety. You may encounter other hazards – learning to identify and deal with them will keep you safe and building your creations for years to come!

== '''Safety When Etching Printed Circuit Boards''' ==

When building many DIY projects, you might want to make your own printed circuit board. This leads to another safety and health issue…the etchants used to dissolve the copper from the board, leaving the traces behind, can pose some health risks. Nothing to be TOO worried about, but once again, something to keep in mind when using, and disposing of, these chemicals! This article is not a complete guide to using these chemicals, but it's hoped that it will point you in the right direction to keep you safe.

The general consensus seems to be: if you are concerned about using etchants, which are acids and CAN burn you, you might want to explore the possibility of ordering pre-made circuit boards. If using a moderately strong acid doesn’t send up red flags, then proceed with knowledge, caution, and respect!

'''BASIC SAFETY''':
When working with etchants, bear in mind that these acids can burn skin, eyes, and even lungs! You'll need to follow basic chemistry lab safety practices. Always work in a safe place free of obstacles/trip hazards that is WELL-VENTILATED (garage?), clear of objects that may be ruined by contact with the acid. Wear appropriate (old) clothing, eye protection, acid-resistant gloves, and do not breath the fumes that may be present near the work area. Keep your face away from the etching container! Etchants and the metals that dissolve into them are poisonous: do not use containers, utensils and the like which will be re-used in the kitchen! No eating, drinking, or smoking during use, and don’t leave etchant where a pet or child could come into contact with it. If heating the etchant, don’t boil it or cause it to spill, and use the same respect for electricity in the presence of liquids that you always would.

Read and understand the manufacturer’s cautions/first aid information, and have a look at the appropriate Material Safety Data Sheet (MSDS) for the compounds you are working with. Know how to deal with spills, ingestion, contact with eyes and other first aid issues before beginning work, and be ready to act - keep whatever materials you might need, such as fresh water and baking soda, nearby. Never dispose of raw, spent etchant down the sink or toilet, or dump it on the ground, and keep it out of the trash…improper disposal could lead to serious environmental clean-up costs, unintended poisoning of driking water wells and the like!

Much has been written on this subject in the forum (thanks to those who took the time to find the info), so I’ve compiled the information that follows from there. Please take the time to read through these valuable forum entries on the subject. As with any DIY project, understanding what risks are present and having a plan to deal with them will help to ensure your safety and health as you enjoy this hobby.
----------------------------------------------------------------------
Ferric Chloride A.K.A. Iron Trichloride, Iron Perchloride
Material Safety Data Sheet (MSDS)
http://www.mgchemicals.com/msds/english/liquid/415-liquid.pdf

Advantages:
Easy to use, sold in premixed form.
Fairly inexpensive and easy to find.
Does a very good job etching.

Disadvantages:
Can cause chemical burns! See MSDS for other health concerns.
Stains almost everything it comes into contact with.
Will corrode other metals.
The chemicals dark reddish color makes it difficult to check etching progress.

Tips:
Works best when warmed. 100 - 120 degrees Fahrenheit or 38 - 49 degrees Celsius is hot enought. Do Not Boil!
Aerating and or agitating also speeds etching.

Disposal: I can't explain it any better than Mark Hammer already has. Thanks Mark!
http://www.diystompboxes.com/smfforum/index.php?topic=50426.msg377103#msg377103

Baking soda (NOT baking powder) will produce a chemical reaction with ferric chloride that will render the solution relatively harmless to the environment. It is how I have been disposing of my etchant for decades now.

Note the following, though:

Like any rapid chemical reaction, heat is produced so you do NOT want to engage in this on a large and rapid scale; a little bit at a time, wait for it to settle down, and then continue with a bit more
The reaction results in a foam-like substance being produced which dries into something that looks like rust-coloured styrofoam. The byproducts of the baking-soda/ferric-chloride interaction occupy about 7-10x the volume of the original ingredients. This means that if you have a tub of etchant, filled to the brim, and you dump a box of baking soda into it, the reaction will overflow the container and cover your counter with ooze within 20 seconds or so. Keep in mind that the "ooze" is partly de-activated byproduct by also not-yet-deactivated etchant which will stain for life anything it comes into contact with. So, you will need a large container (or else place small amounts of your main etchant bath in a medium container) to contain the whole mess or else you risk something you will deeply regret.
The thing about the etchant is that it may LOOK completely treated when it isn't. You may have just a small residual film at the bottom of the container, and when you dump a few tablespoons of soda on it, it starts foaming like crazy. You will want to keep applying the soda until the rust-coloured mess you have is fairly dry in texture. Once you have turned it from wet and dangerous into dry and harmless, you can simply pour all those crumbly bits into a garbage bag and set it out with all the other household waste.

Finally, etchant can often be extended for use a bit longer. If you have a way of safely storing and transferring the stuff to another container, let your bath sit idly for a couple of days (at least) so that all the copper precipitates are sitting like a thick mud at the bottom. GENTLY pour the still-useful etchant from the top into another container. Now you can dump your baking soda into the thick stuff to finish using up whatever molecules of ferric chloride are still around.

Ammonium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/410.pdf[url]

Sodium PerSulphate
MSDS [url]http://www.mgchemicals.com/msds/english/solids/4101.pdf

== '''Painting Safety''' ==

Spray painting your DIY enclosures is not a high-risk endeavor, but there are still a few things to keep in mind.

'''Ventilation''': When using spray paints and solvents, always work in a well-ventilated area. The build-up of paint fumes can cause headaches, neurological damage, and respiratory distress, and the strong odor is a sign that you’re being exposed to the numerous chemicals present in the paint. You want to minimize how much of the stuff you breathe in. Work in short bursts so that you don’t have to be in the same area with the fumes for a long period of time. Respirators aren’t a bad idea, but they don’t tell you how much oxygen is present. For proper use they require professional fit-testing and training in what they can and cannot do, which cartridges to use, etc.

'''Eye protection''': Always wear appropriate eye protection when painting. It’s easy to get the spray nozzle reversed and take a hit in the face!

'''Fire Hazards''': Paint and solvents are HIGHLY FLAMMABLE! Don’t store them where they can pose a fire risk, and be sure solvents are well-labeled. Don’t use them around potential sources of ignition (smoking materials, furnaces, or any other sources of flame or spark). Theoretically, enough fumes could be generated in an enclosed area to create a combustible atmosphere - remember to ventilate! Rags soaked in paints and solvents should be spread over a surface such as a workbench and left to thoroughly dry – don’t toss them in the trash, as they could spontaneously combust!!

'''Solvents''': It was pretty common in earlier years to clean up with solvents such as paint thinner. This is very effective, but it’s also one of the most direct routes to toxic exposure! The compounds present in solvents, even low-VOC ones, leads to liver damage and can be carcinogenic, and is also highly flammable. Wash with soap and water if you get some on your hands. Save the thinner for cleaning overspray…get one of the citrus-based non-toxic hand cleaners for cleaning skin.

Safety

2006-11-11T14:16:15Z

Idlechatterbox: /* Some Thoughts on Safety */

Frequently Asked Questions (DIY FAQ)

2006-11-08T18:02:23Z

Idlechatterbox:

DIY Stompbox FAQ.

Copyright 2006 by Aron Nelson, All Rights Reserved.

Here is info to help you get around problems I had when I was starting out...

[http://www.diystompboxes.com/smfforum/ QUESTIONS??? Join us in the DIY Stompbox Forum]

[http://www.diystompboxes.com/smfforum/index.php?board=6.0 Try a beginner project.]

[http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques How to mod your pedal.]

[http://www.diystompboxes.com/wiki/index.php?title=Debugging Already built a pedal, but it has problems?]

== GROUND ==

'''What is that upside-down triangle - is that ground?'''

http://www.diystompboxes.com/pedals/ground.gif

Yes, it is ground.

'''Where do the connections that show a ground symbol go to?
'''

Generally speaking, take all the ground points, connect them together, then connect them to the ground lug of the input or output jack. Take the power supply (i.e. battery) and connect it to the ground lug as well. If you want the input jack to switch your battery on and off, then connect the lug to ground as before, but connect the battery terminal to the middle connector (i.e. "ring")of a stereo jack. When a mono plug is inserted, the ground circuit will be complete and the switch will be on. Note that some circuits connect the + or positive terminal of the battery to ground (positive ground circuit), although it is more common to connect the negative terminal to ground. The sleeves of the input and output jacks usually go to ground as they are usually connected to the metal casing and the ground lug - unless they are isolated jacks (in which case you need to ground both jack sleeves with a ground wire). In general, metal jacks are not isolated from metal enclosures. If your box is painted you might consider scraping off some paint so the jacks can make contact with the metal on the box so the box can act as a shield; lock washers may do this as well.

== POTS ==
'''Pots - How do I wire pots?'''

Apparently there's a standard for the terminals. When looking at the back of the pot (side opposite the shaft sticking out) with the terminals facing left, from top to bottom they are labeled 3,2 and 1. The terminals correspond to the schematic terminal wires.

http://www.diystompboxes.com/pedals/pot.GIF

When viewed from the front, a pot turned fully clockwise connects terminal 2 to terminal 3. Fully counterclockwise connects terminal 2 to terminal 1.Anyway, I know I have connected pots like this but they were still backwards. If that happens, simply swap the wires connected to terminals 3 and 1.

'''Pots - When do I use audio or linear taper pots?'''

You can use either one at any time. The taper may not be as optimum on some applications. The basic rule of thumb is use audio for volume and sometimes drive, use linear for everything else. That being said, you can use linear for everything. Linear pots will always "work". You can also turn a linear pot into a psuedo audio pot - read the next question.

'''Pots - What is the difference between linear and log or audio taper and how do pots work?'''

[http://www.geofex.com/Article_Folders/potsecrets/potscret.htm Check out the Secret Life of Pots at GEO.]

Pots - I'm looking at a pot with the stem pointing at me. On the left side there is this little metal bit that sticks up. Why is that there?

From Joe Gagan: Some electronics manufacturers cast or drill a little hole in their enclosure to receive that tab on the pot as an additional anti-spin technology. You can either add that hole yourself, or break off the little tab with some pliers like most of us around here do.

'''Pots - How can I test a pot to see if it's linear or log taper?'''

From paul perry (Frostwave):Just put the shaft to half way. If it is linear, then it should measure the same value each way to the ends.(from wiper/middle to each outer lug) If not, it is log.

== CAPACITORS ==

Here is a picture of various types of capacitors. Picture courtesy of Brad Fajardo

http://www.diystompboxes.com/pedals/Caps.jpg

The most common types are Ceramic(they are cheap and generally used for small values), PolyesterFilm (common at Radio Shack) and Electrolytic. The other typescan be used but are more expensive. Electrolytics are polarized;i.e. they have positive and negative terminals, just like a battery.

There are two very common packages of electrolytics that you will run into; Axial and Radial. As you can see below, the difference is where the leads exit the capacitor. I like Radials because they take up less space on the board.

http://www.diystompboxes.com/pedals/axrad.JPG

This is what a typical electrolytic capacitor looks like. The side shown is the NEGATIVE side of the electrolytic. I have read in books that the the positive side is sometimes marked, but so far I have only seen the negative side marked in the capacitors I buy in the local stores.

http://www.diystompboxes.com/pedals/electro.GIF Radial capacitor with negative side showing.

Note the 16V on the electrolytic, this is the voltage rating of the capacitor. For our stompboxes,16V or 35V or anywhere in between is fine,. When you shop around, try and get the cheapest capacitor in this range. Sometimes the 35V will be cheaper than the 16V. Save money and buy the less expensive one.You can use any voltage capacitor as long as the voltage of the circuit you are using doesn't exceed the voltage rating. As long as you can fit the capacitor and the voltage rating is fine, you can use it.

Here are some common electrolytic symbols that you may encounter. In the following example, the negative lead would be facing down and the positive lead facing up.

http://www.diystompboxes.com/pedals/elposneg.gif

Here's a [http://xtronics.com/kits/ccode.htm link to a page that describes how to read capacitor values.] [http://www.repairfaq.org/REPAIR/F_captest.html Here's more about capacitors.]

As usual, [http://www.diystompboxes.com/pedals/rgcaps.html R.G.posted a great explanation about the subjective world of capacitors:]

Also check out [http://members.aol.com/sbench102/caps.html the sound of capacitors.]

[http://people.deas.harvard.edu/~jones/es154/pages/nicetut/book2/inside_cap.html What's inside a capacitor?] [http://mhuss.com/Capacitors/ Also check out this page of dissected caps!]

[http://www.hallbar.com/capacitors.html Here's a page of links re: capacitors.]

''Capacitors (AKA Cap)- What kind of capacitors should I use?
'''

In a nutshell, you should use electrolytic when the capacitor is polarized. You can also use tantalum capacitors instead of electrolytic, but these are not commonly used. For any others, the basic consensus is to use film caps if they fit, otherwise use a mixture of film and ceramic capacitors. For most of our circuits, use caps with a minimum 16 volt rating. [http://geofex.com/ R.G.] posted a [http://www.diystompboxes.com/pedals/rgcaps.html great explanation] about the subjective world of capacitors. For distortion circuits, others have noted that cheap ceramics sound good too, so use your ears! In general, 1uF and up will be electrolytic, any smaller values up to .001uF can be film types and picofarad values like 10pf-470pf are usually ceramic types. This is usually due to size, cost and availability. With the exception of elecrolytic and tantalum capacitors, most capacitors such as film or ceramic are non-polarized (often labeled NP). The orientation of a non-polarized capacitor doesn't matter; there's no positive or negative.

http://www.diystompboxes.com/pedals/elposneg.gif

An interesting point to consider is that most vintage pedals used cheapo ceramic disks.

'''Capacitor - I can't find xx uF capacitor!
'''

You can put two or more capacitors in parallel and their values will add up. This way you can substitute common cap values for hard to find ones. For example: for a 20uF cap, you can put two 10uF caps in parallel.

'''Capacitors - I saw this weird capacitor symbol on a schematic, it had plus signs on both sides! What is this?
'''

It's a non-polarized capacitor often labeled.From Jack Orman:You can simulate a non-polarized by using 2 electrolytic caps. Connect them together negative to negative and use the positive leads as the component leads; which is probably why someone notated it as +-||--||-+ Each of the capacitors should be double the value that you need for the circuit because of the series capacitance formula:Ctotal= 1 / (1/C1)+(1/C2)

'''Capacitors - I don't really understand the units of measurements.... uF, pF etc....'''

[http://www.diystompboxes.com/pedals/capvalues.html Read R.G.'s great units explanation.]

'''Capacitors - Can I put a non polarized capacitor in place of an electrolytic (one that has plus and minus signs)?'''

Yes you can. It's more troublesome to do the other way - to put an electrolytic in place of a normal capacitor since you have to orient the capacitor the correct way or bad things could happen. Don't do this on high power circuits though. For most 9V stompboxes, this should be fine. How do you know which way to orient the polarized cap? The connection point with the larger voltage faces the positive side of the cap. (Use your meter)

'''Capacitor - In general - how do I orient an electrolytic capacitor?'''

The positive side of the polarized capacitor goes to the side (connection point) with the higher voltage. (Use your meter to see which connection point has the higher voltage.)

'''How do you switch between different input caps?'''

From Mark Hammer:

There are several ways to do so. There are two principles to keep in mind:
: 1) Caps store charge, so when caps that have charge stored with nowhere to "bleed off" are reconnected again, there will be a surge of charge being drained that you will hear as a pop. This is why some pedals with a "hanging" cap at the inpt or output will pop with a true bypass (straight wire) unless there is a bleed-off resistor to ground. Bottom line - you don't really want to have any caps with free ends if you can help it.
: 2) Capacitance is additive in parallel not in series. In series it behaves like resistors in parallel.

: So, if you want to switch caps *without* popping, the smart way to do it is to do something like what John Hollis did on the Zombie Chorus. The cap that sets the clock speed is actually two .001uf caps in series. As a pair of series caps, their effective capacitance is actually 500pf (like I said, caps in series behave like resistors in parallel). Shunting out one of those caps with a SPST switch turns it into one .001uf cap when the other is bypassed. For a Rangemaster bottom-cut or "fat" switch, you start out with two equal value series caps chosen so that *half* the value of one of them is equal to the stock input capacitor. When you shunt one of the caps (either one will do), the effective capacitance now becomes doubled and the lowend rolloff drops by an octave to fatten things up.

: I should emphasize that this method is one you would use if complete and total avoidance of popping is your objective, for instance if you wanted a "fat" switch to be a stompswitch you could use mid-riff. If your intention is to have it be a set-and-forget function, then a little popping during breaks won't kill anyone and you can consider other options.

: The "other" options include having something like a 6-position rotary switch that adds other caps in parallel with the stock one to achieve larger effective capacitances and drop the low-end rolloff even further down. Quite frankly, I wouldn't see much value in going beyond 3 settings, but it's your perogative. Three settings could be easily attainable by using a 3-position (centre-off) SPDT toggle-switch. The middle position of the switch adds no additional cap, and the two outside add one of two other values in parallel to achieve 3 different effective input cap values. The drawback with this is that it doesn't lend itself to stompswitching, but as I said, that may be a non-issue in your context.

: Another of the "other" options can be seen in Joe Gagan's clever Fuzz Face adaptations in the Skyripper, Easyripper, etc. Here, he uses two fairly different input cap values with a variable resistor ahead of the larger one. This permits greater and lesser amounts of signal to pass via the larger cap, introducing degrees of fatness. This is more flexible than the first option noted above, and can implement a footswitch for mid-riff changes. For instance, you could use the footswitch to bypass the variable resistor (cap remains in effect) so that you can go from whatever your preset amount of fatness is to full fatness. The problem with this, of course, is that the "full fatness" may be a whole lot more than you want so you'll need to make some thoughtful choices. The other drawback is that you only have 2 choices available from a stompswitch perspective. On the other hand, that is no different than pedals which have variable boost with a 2-choice stompswitch to select between preset boost and no boost.

'''Do vintage pedals always sound better than our copies?'''

From Mark Hammer:

: There are some things where there are clear identifiable changes in design or technology over the years that resulted in a decline in desirability or quality. For example changes to the Fender amp circuits when CBS took over that may have been intended to "improve" them ended up being unliked/unloved by musicians, in comparison to the blackface and earlier designs.

: Similarly, things like the changeover from first generation BBD-chips to second-generation ones in addition to reduced performance control made the early-80's BOSS flangers and chorus pedals less desirable than the mid 1970's ones.

: But is *everything* older necessarily better? Is a Raytheon 4558 from 1977 "better" or any different than a new one? Do the same ostensible components and design somehow magically change in quality a decade later the way that a new chef comes into a greasy spoon and suddenly everything tastes better (or worse)?

: In some cases, I think the absence of forums like this 25 years ago made it very hard to exchange information about pedals and other music technology, and in the absence of information legends and myths emerged about some pedals and other devices that were hard to debunk or clarify simply because people didn't/couldn't know enough. Heck, in 1973, I was playing in a band through a borrowed blackface Bassman head and a homebrew bottom with a 12" Radio Shack speaker. Why? Because someone had told me that Bassmans made great guitar amps, or so they had heard. Of course 30 years later, I now know that it wasn't just *any* Bassman but those of a certain period. Being blessed with having an authentic 59 Bassman I can honestly say that it *does* sound great with guitar but I can also say that it sounds nothing like what that old blackface head sounded like. Of course, that didn't stop me from being influenced by a rumour containing partial or incomplete truths 30 years ago.

: Same deal likely goes for legends about some pedals. A certain artist uses a pedal for a famous song. Of course what never gets revealed broadly is that the effect was applied post-production by an engineer using the tape as source, or that it depended on pushing an amp and miking it a certain way, but somehow the pedal is seen as the source of the desirable and legendary tone and the myth gets cast in stone. If no "famous" artist duplicates the unique set of circumstances after that time, then the legend persists that recent versions of the pedal simply don't cut it, even though there may well be no substantive change in the pedal itself other than opting for different artwork or more economical packaging techniques.

: I'm not saying that *everything* new sounds exactly like everything old. Rather, some things will, for identifiable reasons (which may be as dumb simple as component tolerances), and some things won't. The task is to enumerate a list of reasons why/when vintage stuff will sound, if not better, at least different.

: I'll start the ball rolling. All of this assumes that the same basic circuit is in place:

: 1) Changes in available components: Many of the op-amps we have come to know and love were unavailable or costly in the 70's. Many of the BBD's we came to know and love effectively became unavailable after the early 1980's.

: 2) Changes in power supply and related issues: How things are powered, and the operating voltages produced after things like circuit protection are introduced can have an impact.

: 3) Variations due to component tolerances: Some components are more precise in value than others. If a manufacturer hand-picks the components they can assure consistent quality, but if they don't you can end up with happy accidents and stinkers coming off the same production lines.

'''What capacitors/resistors do you buy? Where do you purchase them from?
'''

Check out my [http://www.diystompboxes.com/pedals/buy.html purchasing parts page.]

== POWER SUPPLY ==

'''Power Supply - I see this symbol and I know it's a battery, but which end is positive?'''

http://www.diystompboxes.com/pedals/batt.GIF

The end with the longer line line (in this case vertically) is the positive terminal, so...

http://www.diystompboxes.com/pedals/battpol.GIF

the left side is positive and the right side is negative.

'''Power Supply - I see V+ mentioned in some schematics, for a 9V battery powered device, does this mean the PLUS end of the battery?
'''

Yes. You make sure that all V+ connections are connected together and that the PLUS or POSITIVE side of the battery is connected to them. V+ basically means the most positive voltage of your pedal; usually 9 volts. V+ is sometimes also called Vcc (+). Vcc(-) in most circuits we use would be ground (or the most negative voltage).

'''Power Supply - What is V.R., V.B, VREF, 1/2V+ etc....?'''

Well, V.R. is voltage reference and 1/2V+ is 1/2 of your most positive voltage (usually 9 volts). Usually they are one and the same and you can typically see V.R. connected to a resistor that connects to the input of an op amp as in the Shaka Braddah 3, The Rat and many others. Basically if you see 4.5V or V.R. or 1/2V+ ( all the same), you find all the places on the schematic that reference the label and connect them together. So all of the places that reference V.R. would connect together; one of the connections actually creates V.R. or 1/2V+. The connection that usually creates V.R. or 1/2V+ aka 4.5V (for a 9V battery) usually is a voltage divider. Typically two identical resistors, one to V+ (such as 9V), the other to ground. The place where they connect is V.R. or 1/2V+.

http://www.diystompboxes.com/pedals/VR.JPG

An example of 1/2V+ also known as V.R., V.B., VREF, 1/2V+ etc...

'''misc - I'm looking at a PCB and I see points A,B,C,Grnd,V+ etc... Where do they connect to???'''

They are usually places where you put a wire into the board and it connects to a potentiometer or ground wire of the input jack or the plus side of a battery. Look at the schematic for the PCB and these points should be labeled.

'''Power Supply - I would like to try running my pedals at 18 volts with 2 batteries. How do I get 18 volts out of 2 batteries?'''

Take 2 battery clips, connect the black (negative) of one to the red (positive) of the other clip. Now use the two remaining clips as usual, when you measure the voltage with a multimeter with fresh batteries, you will measure around 18 volts.

You should verify that your capacitors are rated to handle the higher voltage.

'''What is series and parallel when connecting two batteries? What is the difference in voltage?'''

[http://www.zbattery.com/seriesparallel.html Check out this great link]

'''Power Supply - want 18 volts but I want to use one battery.... is this possible?'''

Yes. Check out this simple [http://www.diystompboxes.com/pedals/vdbl.html Voltage Doubler Circuit.] [http://www.geofex.com/circuits/circuit_sweepings.htm Check out GEO's circuit sweepings!] In general, if you can, use 2 batteries - it's easier.

'''Power Supply - How can I get a negative voltage out of a single battery for a bipolar power supply?
'''

Check out the ICL7660 7662, LT1026, voltage converters. They can double, produce negative voltages etc... from a single battery.

'''I've got one of those SKB powered pedalboards. Is it possible to lop the tip off one of the power cords and rewire it with reverse polarity to power a PNP pedal?
'''

From Zachary Vex:

Only if it's the only pedal you are powering with the power supply. if you are also using that same supply normally with other effects, you'll be shorting +to - at the ground connection when you attach one pedal to another...think about it. the plus side is ground on the PNP box, and minus is ground on the others, then you connect the grounds together...fizzle!

the only way to do it is to connect a second supply that allows you to make the negative connection on your PNP pedal BELOW groundlevel. so you can lop off a connector and reverse it to powera positive ground (PNP fuzz face) pedal, but it has to be connected to a different power supply.

'''How can I protect my circuit from a backwards battery?
'''

[http://www.geofex.com/Article_Folders/mosswitch/mosswitch.htm Check out this article from geofex.comon circuit protection and other tricks.]

'''What is the best way to add a 9V wall wart to my fuzz clone? What can I add in terms of filtering to insure, or at least cut down noise for low noise operation?
'''

From Rob Strand:

The simplest suggestion is to put a 100 ohm resistor in series with the power rail (ie. -rail for PNP, +rail for NPN, not that it really matters) then a 100uF electro across supply, on the effect side.

[http://www.diystompboxes.com/pedals/ps.html Phillip Marshall contributed even more ideas!]

'''How do I put jacks for 9V adaptors on my pedals?
'''

JD did all the work here:

[http://www.generalguitargadgets.com/index.php?option=content&task=view&id=178&Itemid=200 Effects Power Switching and Adding a Power Jack.]

== JACKS ==

'''Jacks - Do I use mono or stereo jacks?'''

Unless you have a special pedal that requires otherwise, use a stereo 1/4" jack for the input of the pedal (so you can unplug your instrument cable to power down the effect) and use a mono jack for output. (See next question for how to wire the input stereo jack). For the output, you use a mono 1/4" jack and the tip lug of the jack is connected to your circuit's output signal and the sleeve lug is connected to ground. The difference between a stereo jack and mono jack is that the stereo jack has 3 lugs (tip, ring and sleeve), while the mono jack only has tip and sleeve.

'''How do I make the input jack switch the power on and off?'''

Get a stereo 1/4" jack for the input of your pedal. Connect the tip connector to the input of the effect. Connect the sleeve to the ground of your effect. Connect the 3rd connector (the ring) to the negative of the battery (or the positive if your pedal uses a reversed power supply such as the Tycobrahe Octavia or some Fuzz Faces). When the cord is inserted into the jack, the ring connects to ground completing the circuit.

In other words, plug in your guitar cable to turn on the circuit, unplug it to turn the circuit off and not consume batteries.

http://www.diystompboxes.com/pedals/qtr.jpg

http://www.diystompboxes.com/pedals/beginners/images/image4.gif

In the above picture, do not assume that the lugs shown are connected to the nearest closest connector. In many cases they are not.

In many cases the lug is connected to the connector farthest away from it. For example, the ring lug is on one side of the jack, but the ring connector (the part that touches the plug) is on the other side of the jack. When in doubt, use your multimeter to test continuity.

'''How do I isolate my jacks from the enclosure?
'''

From R.G.

Two choices:
(a) get insulated bushing jacks like the Switchcraft N1xx typesor the ReAn nylon body ones (excellent choice, that). Mouser has both.
(b) buy the white nylon bushings that Mouser offers. These fit a 1/2" hole and have a 3/8" hole for a standard jack.They're used a lot in isolating input jacks for tube amp hum reduction.

From JD

If you want to go with the nylon washers, here are the Mouserpart numbers for the washers that work with Switchcraft jacks

561-SW375 - Nylon Shoulder Washer
561-D37562 - Nylon Flat Washer

'''1/4" Jacks, open-circuit or closed-circuit?'''

From Steve Daniels/ Small Bear Electronics

: For most pedals, you want an open-circuit stereo jack for the input (Switchcraft #12B), and an open-circuit mono for the output (Switchcraft #11). The "sleeve" contact of the input jack is wired so that the battery is disconnected when the guitar plug is removed. You can see this method of wiring on a number of DIY sites.

'''Tip, ring, what lug does what?'''

Question: All effects circuits have an in and an out.. which lugs do these go on on the jacks?

:The signal of the circuit goes to the tip of the jack. The ground of the circuit goes to the ring of the jack. So the input to the circuit goes to the input jack tip lug and the output of the circuit goes to the output jack tip.The ground of the circuit connects to the sleeve lugs of the jacks.

'''Does the DPDT/3PDT turn the power on and off?
'''
No. If you wire your stereo input jack like described in this FAQ, power is not used when the pedal is unplugged. Power is used whenever the pedal is plugged into the input jack. The DPDT or 3PDT only works on the signall (with the exception of the LED if used) and does not switch the power on and off.

== TRUE BYPASS AND SWITCHING ==

'''Bypass - What is true bypass and what is a DPDT switch?'''

[http://www.geofex.com/Article_Folders/bypass/bypass.htm Read this excellent article by R.G. Keen on bypass methods.]

Also check out my simple [http://www.diystompboxes.com/pedals/articles/elbypass.html Elementary Bypass Article.]

'''Bypass - How do I wire a DPDT switch?'''

Check out this [http://www.diystompboxes.com/pedals/DPDT.gif picture.]

'''Bypass - I have a DPDT but I want to use a 3PDT instead; there are more lugs on the 3PDT, how do I do this?
'''

[http://www.diystompboxes.com/pedals/images/DPDT3PDT.jpg Check out how to go from DPDT to 3PDT.]

'''Bypass - How do I wire a 3DPDT switch with LED?
'''

There are several ways depending on whether you have a "standard" negative ground circuit (most circuits are) or a positive ground circuit (like the Fuzz Face or Rangemaster). Positive ground circuits have the RED wire from the battery connected to ground which is opposite from most "standard" guitar pedal circuits.

For the standard circuits: [http://www.diystompboxes.com/pedals/images/3PDTwiring.jpg standard wiring] and [http://www.diystompboxes.com/pedals/images/3PDTbwiring.jpg alternate (grounded input wiring)] The grounded input wiring is probably better since it grounds the circuit input when in bypass mode.

For positive ground circuits: [http://www.diystompboxes.com/pedals/images/3PDTPNPwiring.jpg standard wiring] and [http://www.diystompboxes.com/pedals/images/3PDTbPNPwiring.jpg alternate (grounded input wiring).]

If you want to omit the LED, simply ignore the middle set of lug connections and omit the resistor and LED.

Also check out this simple page on bypassing: [http://www.diystompboxes.com/pedals/articles/elbypass.html Elementary Bypass.]

'''Bypass - Where do I purchase a DPDT or 3PDT switch?
'''

[http://www.diystompboxes.com/cart/ Support DIYStompboxes.com by ordering from the store]

[http://www.smallbearelec.com/StoreFront.bok For DPDT, order from Small Bear Electronics. (Carling 316)]

'''Bypass - What's the deal with the cheaper switches I see available... can I use them?
'''

Yes. You can use any type of DPDT stomp switch, the issue is reliability. As of 7/1/01, there is no better DPDT switch than the tried and true Carling switches. The other "Arrow" copy DPDT switches are fine for home use where you can swap them out anytime if they fail (and most cheaper switches seem to fail). For gig use, I recommend Carlings. I have heard the Fulltone 3PDT switches are good.

NOTE: I now use 3PDT switches because they are much easier to wire for true bypass. I have found them to be reliable as the Carlings I have and much cheaper. I make them available for a [http://www.diystompboxes.com/cart/ reasonable price.]

'''Bypass - I have an Ibanez Tube Screamer and the switch broke, what can I replace it with?
'''

From CJ Landry: The part is made by E-Switch with the part number TL1100 and the Mouser P/N is 612-TL1100. I have been using this part for a long time when replacing the TS-9 style switch. You might want to add a second source. The second source is also a Mouser part made by Mountain Switch. It's Mouser P/N is 101-0621. The difference between these switches is the square top (on the plunger). The size seems to differ between the E-Switch part and this Mountain Switch part. I have not looked at detailed specs for each switch, but would try the switch which has a longer operating life. This is the number of switch actuations it can handle before it fails. They both work fine and I have no personal preference.

== DIODES ==

http://www.diystompboxes.com/pedals/diode.GIF

Diodes are polarized similar to electrolytic capacitors; there's a positive and negative end. The cathode is the negative end of the diode and the anode isthe positive. The main thing for you to remember is that you need to orient the diode correctly with the schematic.

LED is a light-emitting diode.It has a cathode as well and it is usually marked with a flat side or dot or in some cases a groove in the LED. [http://www.firstpr.com.au/rwi/dfish/leds.html Read more about different LEDs.] Sometimes there is a longer and shorter lead. The shorter lead is usually the cathode (negative), longer lead the anode (positive).

'''Misc - What is Si, Ge??? I see this all the time?
'''

Si = Silicon, Ge = Germanium.

'''Diodes - Give me a quick rundown on basic diode types....
'''

From Rob Strand:

You need to find at least one of each types too have a look at. Most diodes of the same type look similar in size. The size grows and lead thickness grows with increasing current handling. Most diodes have a band at one end which is the cathode and many have a part number stamped on them. Diodes can look similar but may be completely different!!Here a _quick_ rundown on the key points:Germanium: 0.3V, low currents, fast, usually clear+striped bandsSmall signal silicon: 0.6V, low currents, fast, small glass, often copper coloured. Few variations: blue/green/yellow stripes and no part number, black bands with part number, multiple coloured bands and no part number.Power silicon: 0.6V, high currents, slow, usually black plastic with silveror white band and usually a part number.Power silicon-fast: 0.6V, high currents, fast, look same as Power silicon.Small Signal Schottky: 0.35V, look like small signal silicon and zenersLED: 1.8V, unmistakeable, different colours available.Zener: 0.6V one direction and zener voltage in other direction,look like small signal diodes but are often coloured witha part number stampedSmall diodes without part numbers are very hard to identify exactly but are usually small signal silicons or maybe zeners (if it has a number like 5B or 0A (for 5V, 10V) stamped on it).

'''How can I change the kind of distortion I have - or make it more fuzzy using diodes?
'''

[http://www.diystompboxes.com/pedals/mhdistort.html Read this detailed message from Mark Hammer.]

'''When should I use silicon or germanium diodes?
'''

[http://www.diystompboxes.com/pedals/diodes.html Read this detailed message on diodes from Mark Hammer.]

'''How do I wire a FET as a diode?'''

[http://www.elixant.com/~stompbox/smfforum/index.php?topic=38581.0 See here,] and [http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques here.]

'''Anything more on diodes?
'''

Doug Hammond pointed out this link: [http://www.avtechpulse.com/faq.html/ The Unusual Diode FAQ.]

'''What is a low leakage diode and how can I find one?'''

[http://www.diystompboxes.com/smfforum/index.php?topic=16851.0 Check out this thread.]

== TRANSISTORS ==

You will have to work with transistors in some stompboxes. The middle line is the base (B). One of the lines will have an arrow, that's the Emitter (E), and the last line will be the collector (C). If the arrow points away,it's an NPN transistor. If it points in, it's a PNP.

http://www.diystompboxes.com/pedals/npn.JPG NPNTransistor

http://www.diystompboxes.com/pedals/PNP.JPG PNPTransistor

Once you have identified the lines on the schematic, you need to identify the pinouts on the transistor and match them to the schematic. Refer to the diagram that comes with the transistor . Lots of transistors use standard package types. Some transistors have unusual pinouts so always checkthe diagram or obtain a datasheet on the transistor.

http://www.diystompboxes.com/pedals/trans.JPG This picture shows the FLAT side up of the transistor. You will often see this picture in pinout diagrams. Sometime they don't tell you this is the flat side...

'''FETs'''

For all the circuits that use FETs, I now recommend J201 FETs. At a very low cost, they are reliable and great! The have the same pinout as the MPF102 in a TO92 case.

If you cannot get the J201, I also recommend using NTE458 FETs instead of MPF102. The NTE458is about $1.80 around here.

Here is an example of a FET in a schematic that you might see:

http://www.diystompboxes.com/pedals/fet.GIF FET

Note the G (Gate), S (Source)and D (Drain) markings.

Many schematics will omit those markings. Refer to this picture if you get confused.

'''TRANSISTORPACKAGING (Cases)'''

A common thing is for transistorsto use a specific package type.

Here are some common pinouts for some standard package types. Note that there are variations in pinouts and variations of T092 etc... Check your datasheet, which describes the pinout of your component.

http://www.diystompboxes.com/pedals/compin.gif

'''I can't find a xxxxx transistor! Where do I find a replacement/substitute???
'''

Try this: go to [www.nteinc.com www.nteinc.com],click on Semiconductor (for searching) and type in the transistor number.If there is a replacement made by NTE, it will be shown and you can look at the data sheet if it's online. Since NTE and ECG share the same numbers, you should be able to find either NTE or ECGparts at your local electronics store. Usually these replacements will work fine. Only in very special circumstances will the replacement parts fail to work.

'''How do I find out the pin out of a transistor or op amp?
'''

For the most part, go to [www.nteinc.com www.nteinc.com],click on Semiconductor (for searching) and type in the transistor number.If there is a replacement made by NTE, it will be shown and you can look at the data sheet if it's online. On the bottom of the page will be a picture of the pin out. IN MOST CASES, the pin out will be exactly the same as the original part. If it's different,the NTE web site will note that the pin out is different.

Since NTE and ECG share the same numbers, you should be able to find either NTE or ECG parts at your local electronics store.

Also check out these datasheets:

http://www.mouser.com/index.cfm?handler=supplierpage Mouser's Links to companies.]

Also check out:

http://www.repairfaq.org/sam/semitest.htm Basic Testing of Semiconductors]

'''Misc - What is germanium? Where do I find germanium transistors and diodes?
'''

Germanium is a metallic semiconductor and early transistors and diodes were made from it. You can read about the [http://ourworld.compuserve.com/homepages/Andrew_Wylie/history.htm history of the transistor here.] Some early circuits like the Fuzz Face and Tone Benders used germanium transistors. You can find germanium transistors from NTE as well as other electronic places. [http://www.smallbearelec.com/StoreFront.bok Small Bear Electronics] and [http://www.diystompboxes.com/cart/ my store] offers matched transistors for building these circuits. The typically used germanium diode, the 1N34A is available from [http://www.diystompboxes.com/cart/ my store.]

'''Transistors - Can I just stick a germanium transistor instead of silicon in a circuit?
'''

In general, no. You need to rebias the circuit for the germanium transistor.

'''What's up with this "matching" transistors for Fuzz face type circuits? Do I have to do this?
'''

No, you don't have to match them, but the circuit may not sound as good. It has been noted that matching transistors in the Fuzz Face could give you that elusive sound that the highly sought after Fuzz Faces had. GEO has a great article that explains this and most boutique pedals carefully match their transistors by hand. Small Bear has a great article as well! You can do this too. Just buy a ton of transistors and measure each one until you hit the "magical" points on a couple of transistors. Of course this could cost $$$. For a great alternative, utilize the services of Small Bear.

You can also simple rebias your Fuzz Face by altering the bias resistors.

'''Where can I find germanium transistors for Fuzz Face circuits?
'''

How about buying some matched transistors for a really great price!? Go to [http://www.smallbearelec.com/StoreFront.bok Small Bear Electronics] and order a pair.

: Courtesy of Jack Orman:
: Since the supply of 2N388A transistors have been depleted at Parts Express, I thought I'd post a few alternate devices
: that they carry that can be used for F-F construction. Any of the below parts should be suitable and are less than $1
: each. The last one is spec-ed a little weak but would likely be okay. The first one is a good sub for the 2N388A.
: Part No. Type Hfe Price
: 2N1306 NPN 100 $ .95
: 2N1308 NPN 150 $ .75
: 2N1309 PNP 150 $ .75
: 2N1373 PNP 60 $ .95
:
: The NTE101 is another choice:
: http://www.nteinc.com/specs/100to199/NTE101.html
:
: I've heard that the NTE158 might be another choice:
: http://www.nteinc.com/specs/100to199/NTE158.html

'''Darn it! I just bought a TON of NPN Germanium transistors... I thought they were PNP. Can I use them?
'''

Hah! This happened to me. Well, it's pretty darn easy to convert PNP circuits to NPN. Reverse the polarity of the Electrolytic capacitors, diodes and the power supply. It worked fine for my Fuzz face and Tone Bender.... Very nice! (Note, this doesn't work for every circuit, particularly high-gain circuits, but it's worth a try) For PNP to NPN do the same. Reverse the orientation of all electrolytic capacitors, diodes and power supply.

'''Why does my pedal have a horrid crackling or "gating" sound when I play? I have to hit the strings really hard to get it to make sound and it's horrible.....
'''

You have a classic case of a mis-biased transistor(s). Check out the [http://www.diystompboxes.com/wiki/index.php?title=Debugging Debugging page,] especially the section on bias problems.

'''What about biasing a silicon transistor?
'''

Check out [http://www.interq.or.jp/japan/se-inoue/e_dance26.htm this page.]

'''How can I find out more about transistor biasing?
'''

From R.G.Keen:

By far the most comprehensive and comprehensible book on transistor bias and gain that I've run into is "Practical Transistor Circuit Design and Analysis"by Gerald Williams; 1973 McGraw Hill, TK7871.9.W53, ISBN 0-07-070398-1.

'''What is the pinout of the 2N5088/2N5089?
'''

E B C, flat side up, left to right.

'''I see 2N5088 all the time but it's NPN, what's a PNP substitute for the 2N5088?
'''

From R.G.Keen:

Use a 2N4250. 4250 is not exactly a complement of the 5088, but it's pretty good for any silicon PNP uses.

The 2N5087 is also the PNP complement of the 2N5089.

'''What is the pinout of the 2N5087?
'''

E B C, flat side up, left to right.

'''What's a generic replacement for NPN and PNP transistors?
'''

From R.G.Keen:
When in doubt, use a 2N5088 for NPN's and a 2N4250 for PNP's.
You can purchase NPN and PNP transistors from the [http://www.diystompboxes.com/cart/ store.]

'''What's a replacement for the 2N5088?
'''

From R.G.Keen:

2N5089 will work in most instances. Also useful are 2N5210, 2N4401, BC549.

'''What FETs can I substitute in the Mini-Booster and Shaka etc...? I can't find the J201....
'''

From Jack Orman:

This is a recurring question eventhough the information was in the Mini-Booster article at AMZ From the article: "The NTE458 usually has more gain than the J201, and the 2N3686 can provide gain of 500. The 2N5457, MPF102, and 2N3819 will produce less gain. Other substitute transistors include 2N5484, 2SK43, 2SK68, 2SK117, 2SK118, 2SK121, 2SK163 and BF245."

'''What is the pinout of the J201?
'''

It's the same as the MPF102 (see pinout diagram at the bottom of this page). Flat side up, legs pointing down, DSG from left to right.

'''Is there a general spec that tells me if a FET has more gain or not?
'''

From Jack Orman

"FETs with a low V pinchoff usually have high gain. The Yfs (or Gfs) spec is a general indicator of gain as well... Yfs of 1000 is low gain, 3000 is moderate and 12000 is smokin'" (Thanks to Jack Orman for this tidbit!)

'''Where can I get a simple explanation about biasing a FET as an amplifier?
'''

[http://ourworld.compuserve.com/homepages/g_knott/elect247.htm Read about a FET amplifier here at Graham Knott's page.] (Thanks Mike B.)

'''What is the pinout of the BS170?
'''

Flat side up, left to right: D G S. Note that the 2N7000 that is a substitute for the BS170 has a different pinout. The 2N7000 is S G D flat side up, left to right and usually requires a different value bias resistor from the BS170.

'''I see that a lot of pedals you use have FETs, what other types of FETs can I use since I can't find many of them?
'''

Here are some FETs that you can try:

2N5457, 2N5484, NTE458 , ECG458,or J201. The J201 can be found at www.techamerica.com and Future(1800-655-0006). The NTE and ECG FETs should be at most major electronic stores. The 2N series can be found at www.mouser.comas well as all the [http://www.diystompboxes.com/pedals/buy.html other places I list.]

'''What's a good meter I can purchase?'''

[http://www.diystompboxes.com/smfforum/index.php?topic=50673.0 Check out this thread for some suggestions.]

'''How do I measure transistor gain?
'''

The easiest way is to get a multimeter that can measure transistor gain (hFE). The cheapest one I have found is from [http://www.hosfelt.com/en-us/dept_651.html Hosfelt]: 9202- Multimeter, just $12.95.

== RESISTORS ==

'''1/2 vs 1/4 watt resistors which ones???'''

For most if not all of our stompbox effects, 1/4 watt resistors are used. You can use 1/2 watt resistors but they take up more space and do not provide any benefits. Yes, you can mix and match 1/2 and 1/4 watt resistors in a circuit.

'''What does 4K7 and 1K2 mean for resistors?
'''

"That is just the European notation. They replace the decimal point with the multiplier letter.This prevents the possible loss of the decimal point in transcribing data. For instance, 4.7K = 4K7, 1.2K = 1K2, 1M = 1M and so on.

You'll also find the Euro use of "nanofarads", meaning 1/1000 microfarad or 1000 picofarads.For example, 0.001uF = 1nF = 1000pF. 0.022uF = 22nF.

It's handy, and less error prone."
(Thanks to R.G. Keen for this reply in the DIY forum!)

'''I don't have xxK resistor!
'''

You can put two or more resistors in series and their values will add up.

'''I recently read somewhere that using carbon composition resistors in an effect circuit would help to create "brown sound". Are carbon comp. resistors really better to use for audio circuits?
'''

[http://diystompboxes.com/pedals/rgccmp.html Here's a nice article written by R.G.on carbon comp. resistors.]

== OP AMP ==

'''I need to find that JRC4558 chip that's in the TS-808, I heard you can get them from old radios and other voodoo sources!
'''

Yes, you probably can. Or, you can buy the current chip that sounds the same as the original- so close you can't tell the difference... from MOUSER.The part number is:513-NJM4558D.

'''What do all the letters after the numbers mean at the end of an IC?
'''

From Rob Strand:

General letter usage (not justTLO7x, and all options may not be available):

The A and B refers to offset voltage categories. Non-A/B versionshave the highest, then A, then B.

The C, I, M referes to the temperature range, widening/increasingin that order.

The P, N, H, J refers to the package type/material. Usually D means a surface-mount package.

Sometimes the different package material implies different operating temperature ranges.

Basically you are safe with any of these except D. For Audio projects usually the cheapest is OK. Using low offsets, wider temp rangeand different packages _usually_ means you pay more, and if you don't need the options you're wasting your money.

''' GENERAL OP AMP INFO '''

If the circuit uses an IC (usuallyan op amp), then you will see something like this in the schematic:

http://www.diystompboxes.com/pedals/opamp.GIF IC in schematic

In this case, you need to lookup the datasheet for the op amp. Note that you can use a TL071 and have a great low noise substitute for a 741 chip.

In this case, lets pretend it was a TL072 op amp. Here's the pinout for dual op amps such as the TL072, JRC4558:

http://www.diystompboxes.com/pedals/ampins.GIF Dual Op Amps have this pinout (TL072, JRC4558).

Referring to the IC in schematic picture above, the wire going into the minus sign is the InvertedInput/pin 2. The wire going into the plus (+) sign is the Non-InvertedInput/pin 3. Vcc refers to the Vcc (+) input /pin 8. The groundgoes to Vcc(-)/pin 4. The wire exiting the IC in schematic is the Output /pin 1. Since the TL072 is a dual op amp, there are two sets of Input and Outputs. Sometimes circuits will use both amps (inputs and outputs), sometimes it will use only one set. In both cases, Vcc(+) and Vcc(-) will have to be connected. Vcc(+)goes to positive power. Vcc(-) goes to ground. If only one of the op amps are used, the other set of inputs and outputs can be left disconnected. In some schematics, the Vcc(+) (power) and Vcc(-) ground will not be shown. This does not mean you don'thave to connect these pins, you have to; the schematic writer is assuming you already know this..

Let's look at a typical circuit using a popular chip, the LM741. This chip was used in the MXR Distortion+, Dod Overdrive and many others. Although widely used,it's a noisy chip. You can replace the chip with another lower noise op amp like the TL072 if you are building your own circuit. Note if you are modding an existing pedal, use the TL071 - a direct chip replacement.

http://www.diystompboxes.com/pedals/dodexamp.GIF example circuit using 741 chip
http://www.diystompboxes.com/pedals/741.GIF <-LM741 Chip pinout

See how the -(minus) sign is the Inverted Input? See the power V(+) on pin 7 and the ground which is pin 4 V(-). To use a TL072 or equivalent, you need to map the LM741 pinouts to the TL072.

http://www.diystompboxes.com/pedals/ampins.GIF TL072
http://www.diystompboxes.com/pedals/741.GIF LM741

To use a TL072 instead of an LM741:

The connections that connect to Output pin 6 of the 741 connect to pin 1 on the TL072

The connections that connect to V(+) pin 7 of the 741 connect pin 8 of the TL072

The rest of the connections are the same.

Always use IC sockets on yourboard. That way, you don't expose the IC to heat when soldering and you can always substitute a different IC later. For example you can try an RC4558 or TL082 etc...

[http://ourworld.compuserve.com/homepages/Bill_Bowden/opamp.htm#opamp.gif Here's a link to some op-amp basics.]

== WIRE ==

'''What kind of shielded wire should I use?
'''

If you can get it, single conductor with shield - RG-174 Belden wire. Very good and it's flexible too.

'''What kind of wire should I use in my pedals?
'''

In general any type of hookup wire will work - from size 22 gauge and smaller. (The larger the number, the smaller the wire - so 26 gauge is skinnier than 22).I like the "pre-bondedhookup wire" from Small Bear Electronics. It's a cross between stranded and solid core - very nice. In general solid core will stay where you want, but will not like being moved and can break easily. Stranded is much tougher but resists bends and will generally not look as "neat" in an enclosure. Ifthe circuit is being mounted in an enclosure and will not be removed- solid core is ok. If the it's going to be moved at all, I recommend stranded wire or the hookup wire mentioned above from SmallBear.

== ORDERING ==

'''I live in another country, what's a good place to order from?
'''

Try [http://www.futureestore.com/eStore/default.aspx/ FutureElectronics] - a global company with lots of transistors!

'''Where do you buy your transistor sockets from?
'''

If you must purchase, I buy these: Mouser part: 151-TO-1832OG. 151-TO-4320G and 151-TO-18320G. Most 3 pin sockets will work fine.
Most times, I simply [http://www.diystompboxes.com/beginner/build/build%20004.jpg cut up an 8pin DIP now.]

Also see Small Bear Electronics.

'''Where can I get a printed circuit board (PCB) layouts or ready-to-solder board (RTS) for effects?
'''

Check out [http://www.generalguitargadgets.com/index.php?option=content&task=view&id=141&Itemid=154 GeneralGuitarGadgets.com]

== ENCLOSURES ==

'''Where do I find the boxes to put this stuff in?
'''

Commonly called "enclosures"in your favorite catalog, they are made by Bud, Hammond, LMB etc...Aluminum boxes are easy to work with compared to steel. If you want a solution that's cheap but a little harder to work with,check out electrical outlet junction boxes. Thanks to Jack Orman for the tip.

I have been using the 1590BB Hammond box that R.G. recommends. It is so great to build into a box that is sturdy, has enough room and looks good. SmallBear Electronics is now offering the 1590BB for a very good price!. For a smaller box, check out these aluminum enclosures.

== MEASUREMENTS ==

'''How can I measure how much current my pedal is drawing?
'''

To measure the current draw of your pedal, you put your meter in series with the power supply and measure the amperage.

From F Peña:

You have to interrupt the circuit measure current.

Do this:
Set your DMM on DC/mA.
Plug only the - side of the battery to the battery snap.
On the + contact of the battery, touch the red probe and on the free
contact of the battery snap touch the black one.
You should get the reading on the meter this way.

'''How do I measure voltages in a circuit?'''

Set your meter for DC, put the black probe on a ground point and probe using the red probe. Read the DC measurement on the meter.

'''How do I measure inductance?'''

You need a meter that can measure inductance. [http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-570 Here's one.]

'''Testing - I'm testing out a pedal I made and I want to test it out with a function generator. What kind of signal should I use?'''

From [http://zvex.com/ Zachary Vex.]
Put the output of the function generator on a scope, set it for around 400 Hz, sine wave output, 100 mV peak-to-peak, and use a 47k resistor in series between it and the input to your pedal. you can increase the output to as much as 1 V peak-to-peak safely, i think, and you should monitor the output of the generator on a meter or with one trace on the scope while you monitor the output of the circuit with the other trace, if it's a dual-trace unit.

'''Are there other tests I can do with just a multimeter?
'''

Yep, check out: [http://www.repairfaq.org/REPAIR/F_semitest.html Basic Testing of Semiconductor Devices.]

'''Can I test a capacitor with my continuity function?'''

You cannot test a cap with the continuity feature. The continuity feature of most meters will only beep when there is very low resistance.

See this link for more details:

[http://www.repairfaq.org/sam/captest.htm#cttcm Capacitor Testing]

again, thanks to R.G. for finding this great link.

== COMMON WORDS AND TERMS ==

See this section of the Wiki for a list of commonly used terms:

[http://www.diystompboxes.com/wiki/index.php?title=CommonWords COMMONLY USED WORDS]

'''Terms - What is PCB and RTS???'''

Printed Circuit Board and Ready to Solder when related to stompbox electronic projects.

For example:

[http://www.generalguitargadgets.com/index.php?%20option=content&task=view&id=141&Itemid=154 GeneralGuitarGadgets.com]

== CALCULATIONS/FORMULAS ==

'''What is the formula for calculating the knee of a RC (resistor/capacitor) circuit?
'''

This can also be used to calculate the rolloff of an emitter resistor/capactor.

From R.G.Keen:

A resistor and capacitor are halfway to whatever they will do - highpass or lowpass - when the capacitive reactance equals the resistor. That is, when Xc = 1/(2*pi*Frequency)=R, the filter is at its knee. So with a little elementary algebra,Freq. = 1/(2*pi*R*C).

The units are ohms, hertz andfarads.

For the TS series feedback loop(for example), this comes out to
(1/F)= 2 * pi * (.000000047Farad) * (4700 ohms)
= .001387 Sec

F = 720.8Hz.

You can play games with the decimal points. If you use C in uF and R in megohms, you get

F = 1/(2*pi*.047uf*.004700M) =720.8Hz

But I prefer not to mess with remembering special cases of uF/Mohm, etc. Just do it in farads and ohms and keep the decimal point straight.

For emitter bypass capacitors:

From niftydog:

There are three factors that might determine the ƒ rolloff. The input cap, the output cap and the emitter bypass cap. The -3dB point is determined by the "worst" of these formulas.

For ƒlow due to Cin, you need to know the signal source impedance and the input imedance of the amplifier itself. Not a trivial excercise, so I won't go down that path, unless you really want me to!

For ƒlow due to Cout;

ƒlow >= 1 / [2pi.Co(RC +RL)]

Co = output cap, RC = collector resistor, RL = load resistor.

For ƒlow due to CE;

ƒlow >= 1 / [2pi.CE(re +RE1)]

CE = emitter cap, RE1 = non-bypassed emitter resistance.

re is the dynamic resistance of the emitter and can be approximated by;

re = 30mV / IE (±40%)

from Transmogrifox:

Here's the summary that has relevant information that will get you into the ballpark:

----

f3dB ~ 1/ (2*pi*R*C)

----

and R is most significantly defined by the emitter output resistance, so ignore the rest of the effects and just calculate R as

----

R ~ Re ~ Ic/Vt = (Collector Bias Current) / (.025) at room temperature.

----

== DEBUGGING ==

See the [http://www.diystompboxes.com/wiki/index.php?title=Debugging Debugging page in the Wiki]

'''How do I debug and fix my effects?
'''

Check out [http://www.geofex.com/fxdebug/fxdebug.htm GEO's FX Debugging page] and [http://www.diystompboxes.com/pedals/debug.html mine.]

'''I am getting a whine - like feedback but high pitched when I turn the drive all the way up...how can I fix this?
'''

You probably are running the leads of the input and output too close or they are too long. Keep the leads as short as possible when laying out your box. You may also want to consider using shielded wire. To do this, shield the wire on one side only and then connect the single conductor like usual. For high gain boxes, I recommend shielding the input and outputwires from the jack to the switch and from the switch to the board.

You can also try using a 3DPT switch and using the outer connections for signal switching and use the "inner" connections for LED switching.

== POPS ==

'''Pops when switching, even with pulldown resistors'''

From R.G. Keen

: There is a weak link in the power/ground setup in most effects using stereo jack switching. You can get pops when switching the relatively high LED current even if you have pulldown resistors on both input and output caps.

: The culprit is ground noise. The ground noise happens when the sudden start and/or stop of current in the LED makes the signal ground voltage change suddenly. +9V decoupling may not help, and may make it worse.

: The ground noise comes from our friend, the stereo jack ground switch. If your jack is new and the plug is new, things work great. When dirt, oil, crud, bar funk, and other nasties build up on the ground ring of the input jack and the second-channel contact that supplies ground through the plug into the input ground ring, and thence to the effect board, the resistance through that path can get high enough to make a noticeable pop when the LED current starts and stops.

: This sudden transient is worse with mechanical switches because they really do go from fully off to milliohms of resistance in zero time when the metals contact. The sudden "ground bounce" can flow right into the input of your effect, and it doesn't take much to hear a pop from the input of a gain-of-a-zillion MegaBlaster.

'''What to do, what to do??'''

: (1) Clean your plugs and jacks. Yep, and do it again. And again, every so often.(2) Use the OUTPUT jack for power switching - it's less sensitive by the gain of the pedal.

: (3) Use the GEO scheme for cold-switching +9V by using a PNP transistor with it's base tied through a resistor to the stereo lug on the input or output jack, and the battery minus tied directly to the board. The PNP transistor only lets +9 through when its base is pulled down by the plug in the jack, but this current does not change noticeably when the LED is started, and so any ground bounce is only through the hard-soldered milliohms of the battery lead, and is much, much smaller.

: See the power supply switch in the Neutron filter at GEO or at GGG, or see the positive 9V switch in http://geofex.com/FX_images/oaspltr.gif for how to hook up the PNP.

== PEDAL SPECIFIC ==

'''My LPB-1 cuts highs off of my guitar. Anything I can do?'''

From: Matt Farrow

Pharaoh Amplifiers

There are a few things that you can do to increase the treble response.

: 1. Switch to a different device. Any bipolar transistor will have a characteristic high-frequency response and gain. Usually the higher the gain of the transistor the more high frequencies it can amplify. Try a 2N5088 or 2N5089 for a start. 2N2222 can work but will be duller-sounding.

: 2. Increase the input impedance of the circuit. You can do this by changing the biasing resistors on the base of the transistor, keep the same ratio (on an LPB-1/2 it's usually 10 to 1, 470K to 47K - try 1M and 100K) and also by inserting a resistor in series with the base (after the input cap works better but try it both ways.)

: 3. Decrease the input cap to block low freqs. The stock .1 is too much for my ears unless you're using it for bass. Try a .047 or a .033.

'''Any tips for a Big Muff modder?'''

[http://www.diystompboxes.com/articles/bigmuffjcm.html Check out this post from JCM: JCM on Big Muff mods.]

'''I want to mod my wah, any information on this?'''

[http://geofex.com/Article_Folders/wahpedl/wahped.htm Required reading on wahs]

[http://www.diystompboxes.com/smfforum/index.php?topic=39546.0 This thread is very informative re: inductance]

'''I finished building a Foxx Tone Machine (FTM) and it sounds great but I am having problems figuring out how the full wave rectification happens in the circuit. I have scoured my electronic books for some clue but to no avail.'''

From R.G. Keen:

: Consider transformer rectification. A center tapped transformer as in the Octavia makes two versions, one following the input signal and one inverted in polarity from the incoming signal. The diodes allow only the currently-positive version to appear at the output by each letting signal through only when the signal feeding it is positive. This happens on alternate half cycles, so you get full wave rectification.

: In the FTM, the out-of-phase signals are generated in a transistor phase splitter - the transistor with equal collector and emitter resistors. The two diodes are biased slightly on by the resistors around them so that the effect of the diode forward voltage is largely canceled out. But each diode merely conducts when its anode is more positive than its cathode, just as in the transformer case. The diodes think it's the same thing.

'''How can I increase the "slope" of my filter and get rid of the fizziness?
'''

*note* taken from a thread re: the Rat tone control...

From Mark Hammer:

: The "Filter" control on the Rat is, as noted, a single-pole adjustable lowpass filter that will roll off highs by 6db/octave starting from around 475hz (when the pot is at maximum resistance of 100k) and tunable up to 32khz (when the pot is set to minimum resisatance and the filter is determined by the cap and 1.5k fixed resistor). Some folks, myself included, find the upper range of the filter to be relatively useless, and so have changed the filter cap from .0033 to .0047 (or larger). With a .0047uf cap, the tuning range shifts to 334hz-22.6khz, which is a bit better.

:But lets look at the bigger picture...

: The purpose of such hi-cut filters is to take out the fizziness and impart some warmness. Because the filters have such a shallow slope (only 6db additional rolloff for every octave higher), you have to set your rolloff frequency quite low to have any chance of attenuating much higher frequencies to the degree you'd like.

: Think of it like an aircraft carrier. How long would it have to be to accommodate aircraft that needed a long running start to attain liftoff? Fortunately we can shorten the "liftoff time" by opting for a slightly more complex filter without drastically complicating or impairing the circuit.

: If one uses a dual-ganged pot as the tone control, it becomes possible to create a steeper filtering action by having 2 poles (12db/octave rolloff), so that you can have double the reduction in high-end fizziness without having to remove too much of the "body" of the sound. Moreover, the opportunity to cut high end more sharply means you don't really need as much tuning range to achieve a noticeable variation in tone.

: The Rat circuit assumes a total series resistance range of 1.5 to 101.5k. We could duplicate that but as noted, we probably won't need that wide a range. I'm going to shoot for a tunable range of 3.3k minimum resistance for each filter section, to a maximum of 53.3k. In tandem with a .0033uf cap for each section, this gives a 12db/octave filter that can be tuned from a rolloff point of around 900hz to around 14.6khz. If you like it slightly darker, change the 3.3k resistor to 4.7k and your sweep range will be from 880hz to 10.3khz.

: A dual 50k pot is pobably ideal, but lets assume they're a little harder to obtain and work with a dual 100k pot (even RS sells them!). The two pot halves are wired up identically as variable resistors (rheostat) in series with each other, so that at one extreme their combined series resistance adds up to 200k or thereabouts (and obviously 0 ohms at the other extreme). You want their combined resistance to max at 100k, so put a 100k resistor in parallel with each pot half to achieve 50k per pot section. The series resistor doesn't really care which side of the pot it goes on as long as turning the pot produces the same type of resistance change for each section. So, one fixed resistor can go on the input to pot half A and the other on the output to pot half B.

: Instead of a single cap from series resistor to ground as shown in the schematic, put a second .0033uf cap to ground at the junction between the two series resistances (keeping in mind the location of your fixed series resistors).

: This change should produce no decline in max output level (maye even a slight increase since you don't have to kill all the midrange to eliminate the hi-end rasp), although whether a dual-ganged pot will fit in your current chassis is another matter.

'''What's the deal with the limited drive range on an MXR distortion+ clone I made?'''

[http://www.diystompboxes.com/smfforum/index.php?topic=47202.0 Check out this thread regarding the distortion control.]

== TOOLS ==
'''Tools - What's a cool drill bit to buy to drill these metal boxes?'''

Try a Varibit (possibly called a UniBit as well?). These are stepped drill bits that cover pretty much all the holes you need to drill. I bought the smallest size bit (1/2" max) and it worked for everything up to footswitches. About $20 in my local store.

[http://www.lenoxsaw.com/varibit.htm Varibit]
[http://www.irwin.com/ Unibit]

== MISC ==

'''What matters, what doesn't'''

Here's a link to a thread from our forumers that explains what matters to them and what doesn't when starting out. (Complete with colorful posts!)

[http://www.diystompboxes.com/smfforum/index.php?topic=23386.0 What matters, what doesn't....]

'''What is series, what is parallel?'''

How do I connect components in series or parallel?

Series is one component after another. Parallel is when both components are connected so that the components are next to each other with the same leads connected to each other.

http://www.diystompboxes.com/pedals/misc/seriesparallel.gif

'''How do I put 2 components where there is one presently?
I heard that I can put 2 diodes instead of one on my board and it will sound better?
How do I fit 2 diodes or components where there was only one?'''

There are a few ways, but here are a couple.

The first way is if you have vertical space. The second method is if you need to fit the diodes into a tight space.

http://www.diystompboxes.com/pedals/misc/2series.gif
Yes, the diodes are soldered in the "middle".

'''Bypass - I get oscillation/squealing from my distortion when it's bypassed. How do I stop this?
'''

Your pedal has such high gain, that the input needs to be grounded when the effect is bypassed. [http://www.diystompboxes.com/pedals/grndin.JPG Jack Orman's alternate wiring method] does this. If you need an LED+input grounding, use [http://www.geofex.com/Article_Folders/Mill2extn/mil2plus.htm R.G. Keen's Millenium 2 bypass with extensions.]

'''misc - I am picking up radio stations, how can I stop this?
'''

From Eric Hensel: A 47pf cap to,ground, after the input cap will probably do it --you can adjust this up or down --higher values will start to cut treble. use the lowest value that works.

From [http://zvex.com/ Zachary Vex:]

Mount the pc board as close as you can physically to the metal box. this will serve as a ground plane to reduce the heterodyning that can pick up rf. don't let the input and output wires cross... make sure the layout doesn't allow input and output connections to get too close to each other. if you can, solder in ground connections around (near) the sensitive input circuitry. if rf is being picked up by rectification, these fixes won't help, but if it is being picked up due to beat frequencies generated by heterodyning (internal rf oscillation in the circuit beating against rf from radio stations) you can get rid of it through the use of careful layout and grounding to reduce oscillation.

You might try using miniature shielded cable inside of the enclosure for the input to the board too.

'''Bypass - I get a pop when switching my effect in and out. How do I stop this?
'''

The typical method is to put a "pulldown resistor" from signal to ground at the front and end of your circuit. This is implemented as a 1 meg resistor from signal to ground. Just put one at the beginning of your circuit board (before the input cap or start of circuit if no input cap) and another at the end (after the output cap or end of circuit). Look at the many [http://www.geofex.com/ GEO layouts] if you need to see a layout using these resistors. If you are not using high quality switches, it could also be the switch.

'''Bypass - How do I make an LED that shows if my effect is on? Can I do it using a DPDT?
'''

Yes! Check out the [http://www.geofex.com/Article_Folders/Millenium/millen.htm GEO Millenium Bypass.] I have used the Millenium Bypass with bothMPF102 and J201 FETs. The J201 worked well with the white blinking LEDs I got from Radio Shack. The MPF102 worked ok with the Red LEDs I used. Look at the [http://www.diystompboxes.com/pedals/dpdtled.JPG very clear diagram] that Jack Orman wrote for hooking up the circuits. If you make the Millenium Bypass, the wire labeled To Switch connects to the DPDT switch. The +9Vdc connects to the plus terminal of the battery or any +9V connection on the board. The Ground wire goes to any ground on the board or the ground on the jack. The rest of the DPDT is hooked up like the [http://www.diystompboxes.com/pedals/dpdtled.JPG diagram] that Jack Orman wrote up.

'''Bypass - How do I figure out what value resistor to use with my particular LED?
'''
If you know the specifics of your LED, use the following calculators to figure it out. Otherwise, start with a 1.5K resistor and increase the value to make the LED dimmer or decrease the value to make it brighter.

[http://www.muzique.com/schem/led.htm Muzique.com LED Calculator] (Thanks Jack!)

[http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm LED Series Resistor calculator (Bill Bowden)]

'''Misc - What is a breadboard/proto board? Can I test circuits on this?
'''

Yes! A breadboard/proto board is a board with holes that are connected in preset ways. For instance rows of holes will be connected (i.e. wired) together and all you do is stick components into the holes. So to connect a resistor to a capacitor, all you do is stick the resistor lead into a hole, then the capacitor lead into another hole that is "wired" to the first.It's relatively easy to test circuits on a proto board because you can easily substitute different components. The drawback is that the proto board layout can end up not even remotely resembling the layout of the perf board or PCB.

'''Do JFET circuits need a DC blocking capacitor? I see some that don't have them.
'''

From R.G.:

Most JFET amps, like most triode and pentode amps don't need an input blocking cap under most conditions.

This is because the correct bias voltage for most of these circuits is with the gate (or grid) at zero volts and the source (or cathode)a few volts higher. JFETs, triodes, and tubes are -depletion-devices which means that if you do nothing to them, they conduct like mad. Bias for all of these devices involves holding the gate/grid-lower- than the source/cathode to turn them partially off. Thisis most often done by holding the gate/grid at zero volts and placing a resistor between the source/cathode and ground.

At turn on, the gate/grid and source/cathode are both at zero volts, so the current increases through the drain/plate. This same current has to flow through the source/cathode resistor,so it pulls the source/cathode up above ground, reverse biasing the gate/grid a little. Eventually the source/cathode rises enough that the voltage between it and the gate/grid is just right to keep that amount of current flowing and so it stabilizes at that current. It's so-called self biased.

This is different from bipolar transistors and enhancement mode MOSFETs. These devices are normally off, and you have to do something to the control electrode to make them turn on a bit.

In any case, the correct voltage for many JFET and tube circuits is zero volts DC on the gate/grid, and that just happens to be the only voltage that doesn't need a coupling cap.

'''I wish I could make a cabinet simulator; that way I could record direct and play through my boom box etc...
'''

You can. Check out the [http://www.diystompboxes.com/pedals/schems/msim.jpg Marshall type cabinet simulator.] This does not replace a miked amp,but is usable and sounds good when going direct.

'''How do I cut fiberglass PCB boards?
'''

From Paul Perry:

I had to do this for a coulple of dozen boards.. Found the best way was to get a 'tile scriber'which is just a knife sized handle with a tungsten carbide point stuck on. You just clamp the board with a metal edge on it &scrape away heavily a few times, then snap on the scoreline. OK it's trivial & obvious maybe, but I tried to cut them in a bandsaw, DONT even think about it, also fibreglass powder is BAD for your lungs.

'''I would like to try and write out a schematic of my effect. How do I do this?
'''

[http://www.geofex.com/Article_Folders/howtrace.htm Read GEO's article on this.]

'''What's an easy-to-use PCB program?
'''

I have heard [http://www.ece.uiuc.edu/eshop/pcbdesign/ Easytrax] is everything we need for making PCBs.

'''What can I use to view/create PDF files?
'''

You can write PDF files with [http://www.cs.wisc.edu/~ghost/ Ghostscript] for free.

'''What about layout software?'''

[http://www.diystompboxes.com/smfforum/index.php?topic=44838.0 Check out the DIY Layout Creator Software]

'''Where can I check out patents? I would like to see what others have done before....
'''

Try these:

http://gb.espacenet.com/ http://fi.espacenet.com/ http://www.uspto.gov/patft/

'''How can I make my own knobs?
'''

From R.G. Keen:

Easiest is to cast them from casting resin or sculpt them from Bondo auto body putty or Sculpy plastic clay. Find some plastic knobs you don't like, and break the plastica way from the brass insert inside the knob to get the insert with its threaded setscrew.

For the bondo version, make a filler plug of parafin wax to keep the hole to the threaded hole free and insert it into the set screw hole. Wouldn't hurt to stuff the shaft hole full, either.

Then mix up the body putty, and start building up the knob body. As the stuff cures, it goes through a "cheesy" phase where it's really easy to cut and shape. Once it fully cures, it is hard and solid, can be sanded to avery smooth surface or sculpted by a Dremel with a burr on it.Then paint.

For the Sculpy (FIMA is anothertrade name) just sculpt the stuff on the insert like modelling clay, and bake it according to the directions when you get it right. Not as durable as Bondo, but easier to work.

If the design is fairly simple,make a wax model of the knob, pour plaster over it to make a mold,and then melt out the wax. Pour in catalyzed casting resin until the level just supports the insert, let it harden a bit to hold the insert in place, then do another pour to complete the knob.As with the bondo, use parafin to keep the setscrew hole and shaft hole free of the casting material and melt it out later.

'''Other people must have asked a ton of questions about all sorts of stuff before right???
'''

Yes! Look at this [http://www.harmony-central.com/Guitar/Faqs/ FAQ archive!!!] from Harmony Central!

'''How can I make a Triangle Knob Big Muff? Where's the schematic? Where's the schematic for a 70's Big Muff.
'''

From R.G. Keen:

To the best of my knowledge, there is no one schematic you can point to as *the* Triangle Knob Big Muff schematic. EH freely substituted parts and values in all its pedals. Stories from original buyers of various versions of the BMP and other EH pedals indicate that the sound quality varied from unit to unit a lot even for the "same" model.

There are 2 versions of traced circuits from real Triangle Knob Big Muffs. As R.G. said, they are both different.

'''What's up with the swell circuit on the Foxx Tone Machine PCB?
'''

From R.G. Keen:
I should have saved my comments on this when I originally posted them. The "swell" circuit on the Prescription Electronics pedal is exactly the same circuit as a 1968(about) article in Popular Electronics by Anthony Leo about building an entire distortion circuit, but it's modestly mis-used to take the output at a place that has a DC level that starts high and drops to about zero over a bit of time. It's also DC coupled out, so the DC level is transferred to the input of the amp that you plug it into. This DC level pushes the input bias of amps that are DC coupled at the input into not carrying signal. Since it's a one-size-fits-all kind of thing, it only works right for amps which have
:: (a) DC input coupling
:: (b) about a 2V range before being pushed into saturation or cutoff on the input
:: (c) NO DC coupling to the speakers!!! Do this on a solid state DC coupled and and you'll fry a speaker. Many tube amps have no input coupling cap, about a 2V range, and are AC coupled, so they work OK. SOME solid state amps are close enough, and can work OK. Some don't work well at all. Oh, yeah. The "swell" circuit only works right when you have very fresh batteries. Older batteries don't make the happy-accident level changing work right. When it works, the volume on each note starts quiet and ramps up to full level, kind of an attack delay. The Experience Pedal is just the Foxx Tone Machine circuit followed by the A. Leo Fuzz circuit, and some very, very complex switching.

'''I have an old 3 knob memory man delay, NOT STEREO. I play it and it passes signal when on and off but no effect. Do you guys think it is the rare mn3005 delay/chorus IC gone bad???
'''

From Mark Hammer

The chip may actually be okay, but you may need to do an adjustment to find out. There should be a trimpot near the MN3005. It provides a DC bias voltage that the audio signal has to ride on in order for the chip to pass the signal through. Sometimes, the trimpot gets knocked out of position or just drifts over a period of time. It may *sound* broken, but is simply not set up correctly anymore. If you can find this trimpot, slowly turn it while you play or feed an audio signal in to the MM. At some point, you should hear the audio signal if the problem is as I describe.

== MISC LINKS ==

'''Is there a simple site explaining components?'''

Check out this site about components....

[http://www.eleinmec.com/category.asp?4 Components Explained]

[http://www.diystompboxes.com/smfforum/index.php?topic=25201.0 Here's a thread re: components]

[http://www.ibiblio.org/kuphaldt/electricCircuits/ Another resource re: electronics]

'''Is there an article explaining how to solder?'''

[http://www.geofex.com/Article_Folders/how_to_solder.htm There's an excellent article on www.geofex.com. Check it out.]

[http://www.diystompboxes.com/smfforum/index.php?topic=39102.0 Here's a thread of useful links from the forum.]

[http://www.diystompboxes.com/smfforum/index.php?topic=49692.msg381070#msg381070 Another thread with useful resource links.]

[http://www.diystompboxes.com/smfforum/index.php?topic=51215.0 Thread about soldering and temperature]

== DESCRIPTIONS/SOUNDS ==

'''What are these boxes? What's a delay, phaser, phasor, etc...?
'''

Check out [http://www.harmony-central.com/Effects/effects-explained.html HarmonyCentral's effect description page] or [http://www.geofex.com/effxfaq/fxdescr.htm R.G.Keen's effect descriptions page.]

'''What did these things look like?
'''

Check out this book [http://www.amazon.com/exec/obidos/ASIN/0879304790/aronwebpage The Stompbox by Art Thompson.] Here's another [http://www.geocities.com/~stompnet/Main/Gallery/gallery.htm place(Stompnet)]

'''You've got so many schematic links here. I don't know what these stompboxes sound like? Which one's should I try?
'''

Yes, there are a lot of schematics. Someone obviously thought the stompbox sounded good enough to document... Here is a link to [http://reviews.harmony-central.com/reviews/Effects Harmony Central's Effects database.] Users write in and voice their opinions. Another way is to look at what stompboxes custom manufacturers are bringing back. Stompboxes like the Colorsound line, the Big Muff etc... If they are bringing it back then it can't be so bad.Try the most popular ones and then try the more esoteric ones.Check out [http://www.tonefrenzy.com/audio_demo.html www.tonefrenzy.com] for great samples that you can listen to. There is a [http://sounds.ampage.org/ number of samples on AMPAGE.] DIYStompboxes.com forum member Basicaudio has a [http://www.mrdwab.com/john/soundclipspage.html web page of samples as well.]

== THE FORUM ==

'''Give me more to read. I want to learn more!'''

[http://www.diystompboxes.com/smfforum/index.php?board=10.0 Check out the FAQ forum]

'''How can I maximize the use of the forum?'''

Use the search functions to locate interesting threads and info.

Certain people regularly post incredible info. Use the search function to list only their posts. You can search by poster name.

If you see someone posting valuable info, do a search on all the posts they have made in the last year or so.

'''How can I add something to this FAQ'''

Send me suggestions/links etc.. via email: [mailto:online@diystompboxes.com FAQ Suggestions.]

Safety

2006-11-08T18:00:55Z

Idlechatterbox: /* Some Thoughts on Safety */

== Some Thoughts on Safety ==

[formatting not done yet]

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

== '''Common Risks and Common Warnings''' ==

'''Capacitors'''
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly. Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

There are a number of sites on the web that are helpful in learning how to safely discharge the caps in your audio gear. As an illustration, the website below recommends the use of a large screwdriver, though technically any insulated-handle tool with a conductive (i.e., metal) end would work for discharging the caps. The general idea is simple enough, to short the cap to ground (almost always the chassis) with the metal tip.

http://www.netads.com/~meo/Guitar/Amps/Kalamazoo/Mods/safe.html#zap

While this method will discharge the cap as effectively as any other method, from a safety standpoint it is far from ideal. Not only is there the possibility of a large spark when contact is made, the sudden discharge can startle the user or damage the components that might be, in effect, arc-welded by the spark. The startle-effect might seem trivial, but reactions and "freak-out" thresholds vary from person to person. I once saw a technician toss a reasonably expensive meter into the air when one of the leads unexpectedly shorted across 120v. Everyone laughed, of course, except him; when you're not expecting it, even a static-electricity discharge from the carpet to the doorknob is, however brief, unpleasant.

Far more sensible is to rely on a technique that bleeds the stored charge, usually by way of a large resistor. The resistor can be connected to the cap in various ways, but the key is to make sure that its wire leads are not connected to you. Some excellent suggestions for how one might do this are contained in this recent thread:

http://www.diystompboxes.com/smfforum/index.php?topic=49434.0

One final thought on the cap-discharge issue. It is tempting to think that as long as one avoids contact with the cap, the risk of electrocution will be eliminated. Assuming that the equipment is disconnected from the wall outlet, this is in some respects true. Note, however, that caps are always connected to other components, and in many cases those components will have relatively large, exposed metal leads. Thus, while you might avoid the caps themselves, say, when changing a tube, if you touch a component that is soldered or in some way connected to the cap, you will still be vulnerable. The lugs on the back of the On/Off switch are a good example. Even with the amp (or other device) unplugged, simply brushing against these lugs can be enough to complete a circuit, and whatever charge the caps had been holding onto, they will gladly transfer to the surface of your skin. Some gifts just aren't worth getting.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

'''Shake Hands with Mr Electron'''

Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

Safety

2006-11-03T18:25:30Z

Idlechatterbox: /* Some Thoughts on Safety */

== Some Thoughts on Safety ==

[formatting not done yet]

At first glance, it might seem that there is little reason for a discussion of safety among those of us who set out to design, build, and modify effects pedals. After all, most pedals operate on 9 volts, which can make tinkering with them feel about as risky as using a flashlight or grabbing the TV remote. Safety considerations, we might reason, are best directed towards those who build mega-watt amplifiers and rig the PA system in the club.

In truth, of course, not all pedals operate on flashlight-level voltage, and the knowhow (as well as the interest) that the DIYer gains in modifying a pedal can lead naturally to a decision to tear into that amp in the corner that suddenly stopped working. Also, when the sound guy is running late at the club, asking the pedal DIYer to take a look at the way the mixing board is wired into the rest of the rack might not seem like such a stretch. Who else are you going to ask, the drummer?

Not only that, let's face it: except for the rare individual who builds or modifies pedals solely for the aesthetic benefit, it is safe to assume that most DIYers will at some point patch their pedals into a signal train that includes an amp (mega-watt or otherwise). At that point, the fact that such amps just happen to be connected to 120v (in the U.S.) is no trivial detail, especially when one considers that by touching the strings of the guitar, the player becomes part of the circuit. All of a sudden, grabbing the remote, even with wet hands, begins to look at lot less risky.

Fair enough, you might say, but what more can be shared about safety and electrocution risks that hasn't already been repeated on 1000s of webpages? Good question, but here's an even better one. Since many of those webpages do contain excellent and reliable information, why would so many people continue to be killed (or at least burned, scared, and left very apprehensive) by electrocution? Nobody seriously believes, outside of Hollywood, that being electrocuted will leave you with special powers, yet it is apparently true that many people each year take unnecessary risks, and not all of them can be dismissed away as being unfortunate victims of sticking a knife into the toaster while hung-over the morning after a party. At least some of those who are injured or killed did know better, and had considerable experience with electronics and audio gear.

Common Risks and Common Warnings

Capacitors
One of the most common of warnings has to do with capacitors. The main thing to remember about capacitors, sorry, "caps," is that they can zap you by doing what they are supposed to do. In other words, a cap doesn't have to go bad or give into peer pressure in order to pose a significant danger to you. A cap is designed to store a charge and, given the right conditions, discharge it, usually very quickly. Things would be greatly simplified, and I for one would feel a lot less nervous if caps had the equivalent of a gas gauge, a way of indicating whether they were charged (i.e., "full" vs. "empty"). Unfortunately, the engineers haven't gotten that far with caps, and even if they do someday come out with "charge gauges" the wise DIYer wouldn't trust them anyway. It is much, much safer to simply assume that the cap is charged, and discharge it. Treat every rifle as though it's loaded, and treat every cap as though it's charged.

The following links are helpful in learning how to safely discharge the caps in your audio gear.

One caveat: it is common for a discussion of cap-safety to arise in the context of tube amps. Those amps, we hear, operate on as high as 450volts, and this can add to the concern over any caps that might be in such a circuit. The rule of thumb, then, is to discharge any caps you find inside a tube amp, BEFORE touching anything else. But solid-state amps often have large caps in their power sections, and while they may operate on what seems wimpy voltage compared to tube amps, they should be taken just as seriously. With both types of amps (or any other audio gear), always (1) unplug the amp, and (2) discharge the caps before poking around inside.

Shake Hands with Mr Electron
Another common warning goes something like this: when working on electrical equipment, always keep one hand in your pocket, or behind your back, strapped to your chairleg, and so on. The warning is usually presented as though it is part of the lore of electronics, dating back perhaps to Ben Franklin (it is uncertain whether he actually flew that kite, and less certain that he did so one-handed). Others will say things like, "I remember, as a boy, watching my papa repair those huge television sets, and he ALWAYS kept one hand in his pocket. It kept him from being shocked."

Here's the rationale behind the warning: if you only reach into the back of the amp with one hand, and you happen to make contact with exposed wiring, or in some other way place your hand into the electrical path, you will "only" get a zap on your hand. This is supposed to be qualitatively different from what could happen if you reach in with both mitts. Do it one-handed, the thinking goes, and the electricity will stop at your hand (or wrist, finger, it's never clear where) and be done with it, without going all the way up your arm, across your chest, stopping to zap your heart, and then exiting through your other hand. At this point, the person giving the advice will usually add some analogies, e.g., look at those birds on the electrical wire, and notice how they aren't zapped, look at the rat that crawls along the subway 3rd rail without getting zapped.

I can't say why your father kept one hand in his pocket, but if he wanted to avoid unnecessary risks, there were better ways to go about it. And as far as modelling your behavior on birds and rodents, you can do better. Yes, the fact that birds don't get zapped does illustrate an important point about grounding and the completing of a circuit path. But here's the real point: your ability to do precise electronic work on the inside of your amp is going to be greatly reduced, to put it mildly, if you force yourself to pretend that you lost an arm in combat. From the pessimist's vantage point, that means that you will spend more, not less, time around potentially lethal charges. So if you want to try to solder one-handed, I suppose you have the right. But it makes more sense to ensure that nothing inside of the circuit can zap you in the first place.

Furthermore, the underlying idea, that the current will never get near your heart if you only have one hand on that charged cap, simply doesn't have physics or physiology on its side. At most, you will make the electricity work a little harder to kill you, and it can cause serious damage without short-circuiting your heart in any case. So, in the end, the one-hand rule is sort of like recommending that someone wear a leather jacket to for protection when confronting a grizzly bear. The jacket will slow the bear down, but there are much better ways to improve your odds of surviving.

An exception to this would be those rare occasions when you need to poke around in an amp while it is on. If you're unsure, you really should think about paying a pro to do this, since even pros don't do it that often or that casually. There are, admittedly, some times when you can troubleshoot a live circuit by gently nudging a wire this way or that (to see what effect this has on hum, for instance). But why take risks when you don't have to? Don't just keep one of your hands out of the way, keep them both out of the way by using a long wooden stick to do the prodding. This, once more, applies only if you're absolutely sure that prodding is the best way. Even with a long stick, you're still inches away from a serious health risk.

Safety

2006-11-03T15:42:18Z

Idlechatterbox:

== Some Thoughts on Safety ==

Simple mods

2006-11-01T02:43:14Z

Idlechatterbox: /* Simple, Easy Mods/Tips & Techniques */

== Simple, Easy Mods/Tips & Techniques ==

Copyright 2006 by Aron Nelson, All Rights Reserved.

Please do not copy these mods and post them on your site. Please link to this document instead.

'''Increasing range/level using diodes'''

If you have a circuit like the Jordan Bosstone or MXR Distortion+ or DOD overdrive 250 and others that have a diode pair creating the distortion at the end of a circuit, you can increase the output level of the circuit with the expense of a little distortion by putting two diodes where there were one. So instead of 2 diodes, you now have four.

http://www.diystompboxes.com/pedals/2diodes.GIF

This mod will increase the output level with the expense of a little distortion.

More diodes in series will also give you a wider range of clean to distorted sound but less distortion when the circuit is maxxed. Something to note is that a germanium diode "clips"at around .3V and a silicon diode "clips" around .6V so you need roughly 2 germanium diodes to equal one silicon diode. A good multimeter will allow you to measure the diode and find out what the forward voltage is. LEDs will clip even later and give you more range of clean to distortion.

Buzzwords: "Touch sensitivity increase", "More feel", "increased gain", "more dynamic range", "less compressed".

See forum thread: [http://www.diystompboxes.com/smfforum/index.php?topic=46362.0;topicseen Thread re: diodes]

'''Mellowing out distortion using a capacitor around diodes'''

You can put a capacitor in parallel around the 2 diode pair and mellow out the high end of the distortion. Increasing the capacitor value will cut out more and more of the highs.

http://www.diystompboxes.com/pedals/2dcap.GIF

Changing the capacitor value will alter how much highs get cut from the distortion. Start with 100pf and start working up. Try 250pf, then 470pf etc..

Buzzwords: "Smooth out", "focus"

'''Asymmetrical Distortion with diodes'''

In the diode pair, make one diode germanium and another silicon. Alternately, put two diodes on one side and one on the other.

http://www.diystompboxes.com/pedals/2d3.GIF

Essentially mismatch diodes to get this. Use a multi-meter that can measure diodes to find mismatches. Apparently some people feel this will give a more "tube-like" distortion. This is useful in both diodes to ground as shown above as well as diodes in a feedback loop like the Tube Screamer.

Buzzwords: "Tube-like mod", "Asymmetrical distortion", "Tube overdrive distortion"

'''Increasing bass response in and out of distortion box'''

If the box has a small value input or output capacitor like.01uF, you can change the capacitor to a larger value such as.1uF and this will feed the unit more bass. If you change the input capacitor to a larger value, you will put more bass into the distortion circuit. If you change the output capacitor to a larger value, you will output more bass after the distortion.

Buzzwords: "Fatten", "Thicker"

'''Decreasing bass response in and out of the distortion box'''

To decrease the bass response going into the clipping part of a pedal, decrease the input capacitor's value. Usually anything smaller than .01uF will start cutting off bass. If you change the output capacitor to a smaller value, you will have the same type of clipping but will reduce the bass response at the end of the circuit. Basically a high pass filter at the end of the pedal. If you make the input capacitor very small i.e. .005uF etc... you will basically make any pedal that boosts into a treble booster!

Buzzwords: "Thin out", "Tighten"

'''Change the capacitor material type'''

A cumulative change you can make is to replace most ceramic capacitors with their film equivalents. Unfortunately, because film caps are usually larger than ceramics, this mod is applicable only to pedals that you build yourself, or pedals that have sufficient space to spare. Subjectively, the difference in tone, between ceramic and film capacitors, is an overall "smoother" sound. If, on the other hand, you want more "grit" to your tone, try replacing the film caps with their ceramic equivalents. Some people feel that cheap ceramics sound more "open" and better for distortion pedals, so you might try these cheap ceramics and see if you can hear the difference. Try them in tone control circuits and other critical areas. Some of my best sounding pedals used cheapo ceramics. You can also try combinations of capacitors. For instance, take two capacitors half the value of the desired combination, and make one a ceramic and the other a film to get a different tone. As another example, in pedal with a .1uF cap, you might try a .047uF ceramic and a .047uF film in parallel to get a .1uF "combo" cap.

Buzzwords: Film Caps = "Hi Fi", "Studio Quality", "Hi Grade"

'''Adding a "softness" or clipping threshold control'''

You can put a pot in series between the signal and diode pair to adjust the clipping threshold of the diodes. This acts like a "softness" control. I saw this described by R.G.Keen.

http://www.diystompboxes.com/pedals/potdiode.GIF

This works well. You can also put the bounding resistor between the diodes and ground.

'''Change the diode type'''

Change the clipping diodes to different types to get different "shades" of distortion. LEDs give more crunch and buzz. Silicon diodes (1N4148, 1N914) are crisper (harsher?) than germanium (1N34a). Germanium (Ge), Silicon (Si), FETs and MOSFET transistors also have diodes in them that you can use as clippers. Try different types in your circuit.

Buzzwords: Ge = "squishy", "tubey", "compressed".

Si = "sharp", "focused","tight", "precise"

FETs/MOSFETs = "Tube-like", "Crunchy"

LEDs = "Crunch", "Buzz", "Less Compressed"

'''Quick and easy transistor changes'''

You can install transistor sockets in your stompbox so thatyou can mix and match transistors easily. Mouser is one place that carries them (Part No: 151-TO-18320G). Use the hFE function on your multimeter to mix and match different transistors with different gains and hear the difference.
You can also order sockets from Small Bear Electronics.

'''Add a bias pot'''

One way to make your distortion a little more versatile is to add a bias pot. You can put a trimmer pot (sold at Radio Shack etc...) in place of any one of the bias resistors (for example on the differential distortion, no drive or bias pot is on the circuit. You can make one by replacing a bias resistor with a trimmer pot or regular pot. Any pot with a value at least as large as the original resistor value will do. Additionally, put a small value resistor in series with the replacement pot for safety. To use a pot as a variable resistor, tie one of the outer lugs to the wiper (middle lug). Now connect the middle lug to one end of where the resistor was and the other unused lug to the other remaining resistor connection.

http://www.diystompboxes.com/pedals/trim.GIF

http://diystompboxes.com/pedals/replaceres.jpg

'''Add a lowpass filter'''

A lot of distortions don't have tone controls. Here is an easy lowpass filter you can add. It will reduce your output a little but if your distortion pedal has lots of gain, this shouldn't be a big problem. If you think about it, this can go right on the lugs of the output volume pot. Use a small trimmer mounted on the lugs of the output pot along with the capacitor.

http://www.diystompboxes.com/pedals/lowpass.GIF

'''Getting more distortion out of an IC-based distorter such as a Tube Screamer
'''

http://www.diystompboxes.com/pedals/sosmod.jpg

excerpt from Jack Orman's Son of Screamer

You can increase the value of the drive pot for a quick and easy mod that will give you more drive=distortion. If the pedal has two or more diodes in series, you can remove one of them to squash the signal down even more. You can also change the diodes to a different type for different "flavors" of distortion. You can also change the .05 capacitor that connects to Vr to .1uF or higher for more bass response out of the unit. To make a TS series circuit brighter, remove C4 (the .22uF to ground after the 1K resistor), this will brighten up the circuit. Another mod you could do is simply reduce the value of the 4.7K resistor R2 and this will increase the gain of the circuit. In order to keep the same frequency response, you will have to play with the value of C2.

Buzzwords: "Extended gain", "more distortion", "more transparent"

'''Add a low cut filter'''

Here's an interesting one to try, put a low cut if your distortion has too much bass. Put this at the end of a gain stage or at the end of the circuit.

http://www.diystompboxes.com/pedals/lowcut.GIF

The pot value is 500K.

'''Create a band pass filter'''

A lowpass filter followed by a low cut filter will create a band pass filter if the lowpass frequency is higher than the low cut frequency. Changing the values of the capacitors will let different frequencies through.

'''Variation on lowpass filter'''

http://www.diystompboxes.com/pedals/var.GIF

Make the first capacitor one value (for example: .01uF), the second capacitor another (.05uF). Make the pot fairly large ~500K. When the pot is centered, very little tone control is applied. This would go at the end of a circuit or even in the middle of two gain stages.

'''Big Muff Tone Circuit'''

I have had good success splicing this tone control in my pedals. This tone circuit goes right before the volume control.

http://www.diystompboxes.com/pedals/mufftone.GIF

To design your own Big Muff filter, check out Duncan's Tone Stack Calculator.

BTW: the Big Muff tone control can be used to create a really scooped mids tone. Play with the Duncan Tone Stack Calculator to see what can be done.

Speaking of the Big Muff, [http://www.diystompboxes.com/smfforum/index.php?topic=10650.msg64913#msg64913 this thread] has a lot of interesting info on modding this beast!

'''Testing EQ changes'''

A great tip provided by R.G. Keen is to put a 5 band graphic EQ in front of your distortion and another at the end. The one in front can be used to gauge how changes to the input cap will affect the tone of the distortion before clipping. The eq at the end will affect how the tone stack might be modified to adjust the final EQ of the pedal.

'''Using amplifier EQs in distortion circuits'''

It is possible to use the tone controls from amplifier schematics in your distortion pedal.

In many cases the tone control will work as-is.

In some cases, you may have to put a "recovery" gain stage after the tone stack to bring the level back up, but this is pretty easy to do.

Using an amplifier tone stack is an easy way of getting 2 and 3 band EQ into your pedal.

The Duncan Tone Stack Calculator can be used to create all sorts of 2 and 3 band EQ in your pedals.

Duncan Tone Stack Calculator.

'''"Refine" your pedal and smooth the tone out
'''

http://diystompboxes.com/pedals/outcap.GIF

A Jake Nagy special! Put a smallish value capacitor on the output lugs of your volume pot (from signal to ground) to clear up the high end "buzz and hash" from your pedal and give it instant smoothness!

Try different values from 220pf to .0015uF or even larger values depending on the amount of high frequency content you want to remove.

'''FETs as diodes'''

You can connect the Gate and Source to make a FET diode. Connect a FET Gate+Source to ground and the Drain to signal. Then connect another FET Drain to ground and Gate+Source to Signal. Try these where you might have your standard silicon diode clippers.

Buzzwords: "More touch sensitivity", "FET sound", "Tube crunch"

'''Germanium Transistors as clippers'''

You can use either germanium transistors (junk ones) or silicon transistors as diodes. No advantage over using their plain old diode equivalents, except that you can now get rid of some of your bad germanium transistors.

Connect the Base and Emitter to make a diode. Connect a Ge Transistor Base+Emitter to ground and Collector to signal, then another Ge Transistor Base+Emitter to signal and Collector to ground.

'''Quick and easy IC changes'''

Most dual op amps have the same exact pinout. Put an IC socket instead of a soldered chip on your board. Now you can easily swap out different op amps to hear the difference.

Is there a difference?

You bet!

Some dual op amp favorites are: JRC4558, TL072, NE5532, LF353 etc....

Consult the data sheet for the chips to verify that they have the same input. You can also do this for single op amp chips too.

You can order your IC sockets from Small Bear Electronics.

'''Ge and Si in Fuzz Face'''

One experiment you can try if you are making your own Fuzz Face is to use sockets for the transistors. Then put combinations of germanium (Ge) and silicon (Si) transistors in the Fuzz Face.

Try an Si for the first transistor and a Ge in the 2nd. Then reverse.Use trimpots for the collector resistors so you can "tune" the bias for each set.

The mod can give you new unique tones.

Remember to put the "same" type of transistors in the pedal. NPN Ge with NPN Si or PNP Ge with PNP Si.

'''Cleaning perfboard from oxidation'''

Sometimes my perfboard can get a bit oxidized before I solder. I use a tiny piece of that green dish scrubber material to scrub the board under water. It works! Just rinse and dry before soldering.

'''Crack it exactly'''

When I want to have a smaller piece of perfboard from a larger piece, I score along the perfboard using an Xacto knife and ruler and then bend the board at the score using pliers. I score along a row of holes and it snaps very evenly.

'''"Secret" of stacked stages'''

It's been said many times by R.G. Keen and others that one of the the secrets to a "good" distortion/overdrive is to:

1: Control the gain between stages

2: Control the bass of the signal

3: Control the high end harmonics generated

Look at most of the overdrives that use transistors and series gain stages....

You will usually find:

Voltage dividers to control the gain between stages as well as other tricks to control gain.

Smallish capacitors (.01uF and smaller) for coupling caps which roll off low end from the signal.

High end roll off caps across the collector/drain resistors or from signal to ground.

Of course "good" in this case is controlled, smooth distortion.

If you want fuzzy, maxxed out distortion and FUZZ, well, then slam the signal as much as you want and forget about the above :-)

'''Testing your pedal'''

Be sure to test your pedal with different types of guitars and amps.

You will be surprised at how different it can sound with other amps/guitars. Humbuckers vs. single coils can make a big difference.

A .01uF input cap is usually a good start for a pedal that can handle both types of pickups.

'''Booster to distortion pedal'''

Simply add back to back (anti-parallel) diodes from signal to ground after the output cap to turn a booster circuit into a distortion circuit.

http://www.diystompboxes.com/pedals/2diodes.GIF

You can put the diodes anywhere on the output as long as there's a blocking capacitor before the diodes.

You can put 2 diodes or 4 for more output. You can also use germanium diodes or silicon diodes.

'''Another Voltage Divider'''

From petemoore:

Super EZ'...works great !!! [an alternative to 'regular' votage dividers]

Take yer LM386 socket, and hookup V+ pin to V+ [9V+/battery] andyer Ground [pin 4] to ground...then you have 1/2v at the output...replaces the voltage divider [two equal resistors usually with a bypass electrocap] and provides a nice 1/2 V tap.

Usually I build this at the right top of the board, first thing, but leave three 'loops' or wires atop the board for ground, V+, and 1/2V connections to be made where I can see them.

Connect the 1/2v wherever you see Vb [Vbias], 1/2v etc. ...Ground and V+ >connect where needed.

Simple neat EZ, works like a charm.

Please do not copy these mods and post them on your site. Please link to this document instead.

Common Terms and Abbreviations

2006-11-01T02:23:48Z

Idlechatterbox:

Some Common Abbreviations and Terms:

active = a class of components, often solid-state, that include diodes, transistors, and operational amplifiers

ADC = Analog-to-Digital Converter

by-pass capacitor = a capacitor that provides a path of low impedance (often as a decoupling capacitor)

cap = capacitor

[http://www.diystompboxes.com/smfforum/index.php?topic=20425.msg125783#msg125783 coupling vs. decoupling capacitor]

CC = Carbon Comp(osition), a type of resistor

CCW = Counter Clock-Wise, the opposite of clock-wise

CW = Clock-Wise (the direction of the hands of a clock), usually refers to direction of rotation of a potentiometer as the wiper (lug 2) goes from lug 1 around to lug 3

CCS = Constant Current Source (there's a nice [http://en.wikipedia.org/wiki/Current_source Wikipedia introduction to simple transistor CCS circuits])

DAC = digital-to-analog converter

DIP = Dual Inline Package, as for many integrated circuits and sockets

discrete = slang for a simple component like a transistor or a capacitor, contrasted with an ''integrated'' circuit like an operational amplifier

DMM = Digital MultiMeter

ground fill = see "ground pour"

ground plane board = a 4 layer pcb on which one of the layers is continuous copper--the changing current in a trace is accompanied by an equal and opposite image current in the ground plane so that there is less induced voltage on neighboring traces than without the ground plane

ground pour = grounded areas of copper on a pcb layer of traces. Note: this is not the same as a "ground plane"

HPF = High Pass Filter

IC = integrated circuit, e.g., an operational amplifier

LFO = Low Frequency Oscillator

LPF = Low Pass Filter

meter = multimeter

MF = Metal Film, a type of resistor often preferred for its low-noise qualities

op amp = operational amplifier

OTA = Operational Transconductance Amplifier

passive = a category of components that includes resistors, capacitors, inductors, transformers, and switches

PCB = Printed Circuit Board. Typically, a thin sheet that has "traces" of conducting material (usually copper) that link the various components and provide a point for soldering.

perf = perfboard. Typically, a thin plastic sheet with pre-drilled small holes for component leads, wires, etc.

pot = potentiometer. Most commonly used to vary the resistance in a circuit. A volume control is nearly always a knob mounted to a potentiometer

PS = Power Supply, generally referring to a source of power other than a battery.

PWB = Printed Wiring Board (same as PCB -- used to differentiate from Polychlorinated Biphenyls)

PWM = Pulse Width Modulation -- describes an LFO or the output of an op amp comparator

RTS = Ready To Solder (commonly used as ready to solder board)

SIP = Single Inline Package, as for some transistors and sockets

SMD = Surface Mount Devices, which are often smaller versions of many familiar components

trim, trimmer = a small potentiometer, often 1/4" or 3/8" square, often used as a variable resistor

TRS = Tip-Ring-Sleeve, refers to a type of 1/4" jack, often called "stereo" and commonly used to manage the power supply in a stompbox with the input plug. In most cases, a stereo jack will have 3 solder points or "lugs," whereas a mono jack will have only 2.

vero = veroboard

xfr, xfmr = transformer

xtl = crystal

Main Page

2006-11-01T02:13:40Z

Idlechatterbox: /* Getting started */

'''DIYStompboxes.com Wiki'''

<span style="color: #880055">From Dave_B: The 'Gallery' has been rolled into the 'Pedal Specific Info' pages in the Construction section. September 30, 2006</span>

== Getting started ==
* [http://www.diystompboxes.com/wiki/index.php?title=LearningResources Learning Resources]
* [http://www.diystompboxes.com/wiki/index.php?title=StockingYourBench Stocking Your Bench]
* [http://www.diystompboxes.com/wiki/index.php?title=CommonWords Common Abbreviations and Terms]
* [http://www.diystompboxes.com/wiki/index.php?title=DIY_FAQ DIY Frequently Asked Questions (FAQ)]

== Construction ==
* [http://www.diystompboxes.com/wiki/index.php?title=PedalSpecificInfo Pedal Specific Info] -- links to schematics, layouts, and construction tips.
* [http://www.diystompboxes.com/wiki/index.php?title=PrintedCircuitBoards Printed Circuit Boards] -- tutorials on making PCB's as well as info on properly mounting them in your box.
* [http://www.diystompboxes.com/wiki/index.php?title=AllAboutEnclosures All About Enclosures] -- info on buying, drilling, and finishing.

== Repair ==
* [http://www.diystompboxes.com/wiki/index.php?title=Debugging Debugging]
* [http://www.diystompboxes.com/smfforum/index.php?topic=38789.msg275394#msg275394 Popping] -- also see [http://www.diystompboxes.com/smfforum/index.php?topic=43035.msg311544#msg311544 Re: Is mechanical true bypass switch popping just an inherent flaw?]
* [http://www.diystompboxes.com/smfforum/index.php?topic=36102.0 Great thread and article by Analog Mike about repairing an old vintage pedal.]

== Reference Material ==
* [http://www.diystompboxes.com/wiki/index.php?title=SchematicSources Schematic Sources]
* [http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques Simple Mods] Simple mods you can do to your pedals.
* [http://www.pat2pdf.org/ Patent to PDF site] retrieve a patent in PDF format
* [http://www.diystompboxes.com/wiki/index.php?title=TechTips Tech Tips] a nice reference for pedal builders. This section is a mix of theory and practice that can help you better understand what's going on under the hood of your effects.

== Links ==
* [http://www.diystompboxes.com/wiki/index.php?title=Links DIYS Link Page] Links to retailers, forum member sites, amp-related sites, etc.

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