Frequently Asked Questions (DIY FAQ) From DIY_Wiki 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... SKILLS you need to build your own stompboxes. (http://diystompboxes.com /wiki/index.php?title=Skills) For the new guys.... (http://www.diystompboxes.com/smfforum /index.php?topic=64141.0) Try a beginner project. (http://www.diystompboxes.com/smfforum /index.php?board=6.0) How to mod your pedal. (http://www.diystompboxes.com /wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques) Already built a pedal, but it has problems? (http://www.diystompboxes.com /wiki/index.php?title=Debugging) Wondering what part does what? (http://www.diystompboxes.com/smfforum /index.php?topic=47572.0) QUESTIONS??? Join us in the DIY Stompbox Forum (http://www.diystompboxes.com /smfforum/) Contents 1 GROUND 2 POTS 3 CAPACITORS 4 POWER SUPPLY 5 JACKS 6 TRUE BYPASS AND SWITCHING 7 DIODES 8 TRANSISTORS 9 RESISTORS 10 OP AMP 11 WIRE 12 ORDERING 13 ENCLOSURES Frequently Asked Questions (DIY FAQ) - DIY_Wiki http://www.diystompboxes.com/wiki/index.php?title=Fr... 1 of 44 19/12/12 14:18
Transcript
Frequently Asked Questions (DIY FAQ)
From DIY_Wiki
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...
SKILLS you need to build your own stompboxes. (http://diystompboxes.com/wiki/index.php?title=Skills)
For the new guys.... (http://www.diystompboxes.com/smfforum/index.php?topic=64141.0)
Try a beginner project. (http://www.diystompboxes.com/smfforum/index.php?board=6.0)
How to mod your pedal. (http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques)
Already built a pedal, but it has problems? (http://www.diystompboxes.com/wiki/index.php?title=Debugging)
Wondering what part does what? (http://www.diystompboxes.com/smfforum/index.php?topic=47572.0)
QUESTIONS??? Join us in the DIY Stompbox Forum (http://www.diystompboxes.com/smfforum/)
Contents
1 GROUND2 POTS3 CAPACITORS4 POWER SUPPLY5 JACKS6 TRUE BYPASS AND SWITCHING7 DIODES8 TRANSISTORS9 RESISTORS10 OP AMP11 WIRE12 ORDERING13 ENCLOSURES
14 MEASUREMENTS15 COMMON WORDS AND TERMS16 CALCULATIONS/FORMULAS17 DEBUGGING18 POPS19 PEDAL SPECIFIC20 TOOLS21 MISC22 MISC LINKS23 SOFTWARE24 DESCRIPTIONS/SOUNDS25 THE FORUM
GROUND
What is that upside-down triangle - is that ground?
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 connectthem 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 yourbattery on and off, then connect the lug to ground as before, but connect the batteryterminal to the middle connector (i.e. "ring")of a stereo jack. When a mono plug isinserted, the ground circuit will be complete and the switch will be on. Note that somecircuits connect the + or positive terminal of the battery to ground (positive groundcircuit), although it is more common to connect the negative terminal to ground. Thesleeves of the input and output jacks usually go to ground as they are usually connectedto the metal casing and the ground lug - unless they are isolated jacks (in which caseyou need to ground both jack sleeves with a ground wire). In general, metal jacks arenot isolated from metal enclosures. If your box is painted you might consider scrapingoff some paint so the jacks can make contact with the metal on the box so the box canact 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 bottomthey are labeled 3,2 and 1. The terminals correspond to the schematic terminal wires.
When viewed from the front, a pot turned fully clockwise connects terminal 2 toterminal 3. Fully counterclockwise connects terminal 2 to terminal 1.Anyway, I know Ihave connected pots like this but they were still backwards. If that happens, simplyswap 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 someapplications. The basic rule of thumb is use audio for volume and sometimes drive, uselinear for everything else. That being said, you can use linear for everything. Linearpots will always "work". You can also turn a linear pot into a psuedo audio pot - read thenext question.
Pots - What is the difference between linear and log or audio taper and how dopots work?
Check out the Secret Life of Pots at GEO. (http://www.geofex.com/Article_Folders/potsecrets/potscret.htm)
Pots - I'm looking at a pot with the stem pointing at me. On the left side thereis this little metal bit that sticks up. Why is that there?
From Joe Gagan: Some electronics manufacturers cast or drill a little hole in theirenclosure to receive that tab on the pot as an additional anti-spin technology. You caneither add that hole yourself, or break off the little tab with some pliers like most of usaround 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 shouldmeasure the same value each way to the ends.(from wiper/middle to each outer lug) Ifnot, it is log.
CAPACITORS
Here is a picture of various types of capacitors. Picture courtesy of Brad Fajardo
The most common types are Ceramic(they are cheap and generally used for smallvalues), PolyesterFilm (common at Radio Shack) and Electrolytic. The other typescan beused but are more expensive. Electrolytics are polarized;i.e. they have positive andnegative terminals, just like a battery.
There are two very common packages of electrolytics that you will run into; Axial andRadial. As you can see below, the difference is where the leads exit the capacitor. I likeRadials because they take up less space on the board.
This is what a typical electrolytic capacitor looks like. The side shown is the NEGATIVEside of the electrolytic. I have read in books that the the positive side is sometimesmarked, but so far I have only seen the negative side marked in the capacitors I buy inthe local stores.
Radial capacitor with negative side showing.
Note the 16V on the electrolytic, this is the voltage rating of the capacitor. For ourstompboxes,16V or 35V or anywhere in between is fine,. When you shop around, try andget the cheapest capacitor in this range. Sometimes the 35V will be cheaper than the16V. Save money and buy the less expensive one.You can use any voltage capacitor aslong as the voltage of the circuit you are using doesn't exceed the voltage rating. Aslong 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 followingexample, the negative lead would be facing down and the positive lead facing up.
Here's a link to a page that describes how to read capacitor values. (http://xtronics.com/kits/ccode.htm) Here's more about capacitors. (http://www.repairfaq.org/REPAIR/F_captest.html)
As usual, R.G.posted a great explanation about the subjective world of capacitors:(http://www.diystompboxes.com/pedals/rgcaps.html)
Also check out the sound of capacitors. (http://members.aol.com/sbench102/caps.html)
What's inside a capacitor? (http://people.deas.harvard.edu/~jones/es154/pages/nicetut/book2/inside_cap.html) Also check out this page of dissected caps! (http://mhuss.com/Capacitors/)
Here's a page of links re: capacitors. (http://www.hallbar.com/capacitors.html)
More info re: capacitors (http://www.uoguelph.ca/~antoon/gadgets/caps/caps.html)
Capacitors (AKA Cap)- What kind of capacitors should I use?
In a nutshell, you should use electrolytic when the capacitor is polarized. You can alsouse tantalum capacitors instead of electrolytic, but these are not commonly used. Forany others, the basic consensus is to use film caps if they fit, otherwise use a mixture offilm and ceramic capacitors. For most of our circuits, use caps with a minimum 16 voltrating. R.G. (http://geofex.com/) posted a great explanation(http://www.diystompboxes.com/pedals/rgcaps.html) about the subjective world ofcapacitors. For distortion circuits, others have noted that cheap ceramics sound goodtoo, so use your ears! In general, 1uF and up will be electrolytic, any smaller values upto .001uF can be film types and picofarad values like 10pf-470pf are usually ceramictypes. This is usually due to size, cost and availability. With the exception of elecrolyticand 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'sno positive or negative.
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 wayyou can substitute common cap values for hard to find ones. For example: for a 20uFcap, you can put two 10uF caps in parallel.
Capacitors - I saw this weird capacitor symbol on a schematic, it had plus signson both sides! What is this?
It's a non-polarized capacitor often labeled.From Jack Orman:You can simulate anon-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 someonenotated it as +-||--||-+
From R.G.
"You can make a quick and dirty NP cap by tying together the negatives of twoequal-sized polar caps.
In the series-NP connection, the capacitance value is funny. Normally caps in series area smaller capacitance than either cap by itself. If you had two 3.3uF polyester caps,then the expected value for two of them in series is 1.65uF. However, electrolytic capsactually conduct in the reverse direction, so two 3.3uF polarized aluminum electrolyticcaps act like they each have a diode in parallel with them that conducts when thevoltage is backwards for that one cap. So two 3.3uF caps hooked up as series non polar(i.e. negative to negative) look like a single 3.3uF NP cap.
... except for tiny region near zero volts where they withstand a tiny reverse voltage, sothey look like 1.65uF there..."
Capacitors - I don't really understand the units of measurements.... uF, pFetc....
Read R.G.'s great units explanation. (http://www.diystompboxes.com/pedals/capvalues.html)
Capacitors - Can I put a non polarized capacitor in place of an electrolytic (onethat has plus and minus signs)?
Yes you can. It's more troublesome to do the other way - to put an electrolytic in placeof a normal capacitor since you have to orient the capacitor the correct way or badthings could happen. Don't do this on high power circuits though. For most 9Vstompboxes, this should be fine. How do you know which way to orient the polarizedcap? 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 thehigher 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 drainedthat you will hear as a pop. This is why some pedals with a "hanging" cap at theinpt or output will pop with a true bypass (straight wire) unless there is a bleed-offresistor to ground. Bottom line - you don't really want to have any caps with freeends if you can help it.
2) Capacitance is additive in parallel not in series. In series it behaves likeresistors in parallel.
So, if you want to switch caps *without* popping, the smart way to do it is to dosomething like what John Hollis did on the Zombie Chorus. The cap that sets theclock speed is actually two .001uf caps in series. As a pair of series caps, theireffective capacitance is actually 500pf (like I said, caps in series behave likeresistors in parallel). Shunting out one of those caps with a SPST switch turns itinto 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 oneof the caps (either one will do), the effective capacitance now becomes doubledand 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 totalavoidance of popping is your objective, for instance if you wanted a "fat" switch tobe 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 canconsider other options.
The "other" options include having something like a 6-position rotary switch thatadds other caps in parallel with the stock one to achieve larger effectivecapacitances and drop the low-end rolloff even further down. Quite frankly, Iwouldn't see much value in going beyond 3 settings, but it's your perogative. Threesettings 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 twooutside add one of two other values in parallel to achieve 3 different effective inputcap 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 Faceadaptations in the Skyripper, Easyripper, etc. Here, he uses two fairly differentinput cap values with a variable resistor ahead of the larger one. This permitsgreater and lesser amounts of signal to pass via the larger cap, introducingdegrees of fatness. This is more flexible than the first option noted above, and canimplement a footswitch for mid-riff changes. For instance, you could use thefootswitch to bypass the variable resistor (cap remains in effect) so that you can gofrom whatever your preset amount of fatness is to full fatness. The problem withthis, of course, is that the "full fatness" may be a whole lot more than you want soyou'll need to make some thoughtful choices. The other drawback is that you onlyhave 2 choices available from a stompswitch perspective. On the other hand, thatis no different than pedals which have variable boost with a 2-choice stompswitchto 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. Forexample changes to the Fender amp circuits when CBS took over that may havebeen intended to "improve" them ended up being unliked/unloved by musicians, incomparison 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'sBOSS 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 anddesign somehow magically change in quality a decade later the way that a newchef 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 veryhard to exchange information about pedals and other music technology, and in theabsence of information legends and myths emerged about some pedals and otherdevices that were hard to debunk or clarify simply because people didn't/couldn'tknow enough. Heck, in 1973, I was playing in a band through a borrowedblackface 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 sothey 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 59Bassman I can honestly say that it *does* sound great with guitar but I can alsosay that it sounds nothing like what that old blackface head sounded like. Ofcourse, that didn't stop me from being influenced by a rumour containing partial orincomplete truths 30 years ago.
Same deal likely goes for legends about some pedals. A certain artist uses a pedalfor a famous song. Of course what never gets revealed broadly is that the effectwas applied post-production by an engineer using the tape as source, or that itdepended on pushing an amp and miking it a certain way, but somehow the pedalis seen as the source of the desirable and legendary tone and the myth gets cast instone. If no "famous" artist duplicates the unique set of circumstances after thattime, 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 thanopting 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 ascomponent tolerances), and some things won't. The task is to enumerate a list ofreasons 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 knowand love were unavailable or costly in the 70's. Many of the BBD's we came toknow and love effectively became unavailable after the early 1980's.
2) Changes in power supply and related issues: How things are powered, and theoperating voltages produced after things like circuit protection are introduced canhave an impact.
3) Variations due to component tolerances: Some components are more precise invalue than others. If a manufacturer hand-picks the components they can assureconsistent quality, but if they don't you can end up with happy accidents andstinkers coming off the same production lines.
What capacitors/resistors do you buy? Where do you purchase them from?
Check out my purchasing parts page. (http://www.diystompboxes.com/pedals/buy.html)
How do I test capacitors?
Here's a site on how to test capacitors (http://www.repairfaq.org/sam/captest.htm)
"Tropical Fish capacitor chart"
Tropical Fish capacitor chart (http://www.diystompboxes.com/smfforum/index.php?topic=75933.0)
POWER SUPPLY
Power Supply - I see this symbol and I know it's a battery, but which end ispositive?
The end with the longer line line (in this case vertically) is the positive terminal, so...
the left side is positive and the right side is negative.
Power Supply - I see V+ mentioned in some schematics, for a 9V batterypowered device, does this mean the PLUS end of the battery?
Yes. You make sure that all V+ connections are connected together and that the PLUSor POSITIVE side of the battery is connected to them. V+ basically means the mostpositive 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 9volts). Usually they are one and the same and you can typically see V.R. connected to aresistor that connects to the input of an op amp as in the Shaka Braddah 3, The Rat andmany 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 ofthe places that reference V.R. would connect together; one of the connections actuallycreates V.R. or 1/2V+. The connection that usually creates V.R. or 1/2V+ aka 4.5V (for a9V 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+.
How is VREF calculated?
Again, GEOFEX.COM (http://www.geofex.com/circuits/Biasnet.htm) has a greatexplanation!
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 theyconnect to???
They are usually places where you put a wire into the board and it connects to apotentiometer or ground wire of the input jack or the plus side of a battery. Look at theschematic for the PCB and these points should be labeled.
Power Supply - I would like to try running my pedals at 18 volts with 2batteries. 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 theother clip. Now use the two remaining clips as usual, when you measure the voltagewith 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 thedifference in voltage?
Check out this great link (http://www.zbattery.com/seriesparallel.html)
Power Supply - want 18 volts but I want to use one battery.... is this possible?
Yes. Check out this simple Voltage Doubler Circuit. (http://www.diystompboxes.com/pedals/vdbl.html) Check out GEO's circuit sweepings! (http://www.geofex.com/circuits/circuit_sweepings.htm) In general, if you can, use 2 batteries - it's easier.
I purchased a wall wart and even though it says 9 volts, when I measure it I get14 or 16 volts. What's going on?
You have an unregulated power supply. You can turn it into a regulated power supply byusing a voltage regulator like the LM317. See this thread.
I've got one of those SKB powered pedalboards. Is it possible to lop the tip offone of the power cords and rewire it with reverse polarity to power a PNPpedal?
Power Supply - How can I drop 9V to 5V easily?
Drop 9V to 5V (http://www.diystompboxes.com/smfforum/index.php?topic=76044.0)
From Zachary Vex:
Only if it's the only pedal you are powering with the power supply. if you are also usingthat same supply normally with other effects, you'll be shorting +to - at the groundconnection when you attach one pedal to another...think about it. the plus side isground on the PNP box, and minus is ground on the others, then you connect thegrounds together...fizzle!
the only way to do it is to connect a second supply that allows you to make the negativeconnection on your PNP pedal BELOW groundlevel. so you can lop off a connector andreverse it to powera positive ground (PNP fuzz face) pedal, but it has to be connected toa different power supply.
How can I protect my circuit from a backwards battery?
Check out this article from geofex.comon circuit protection and other tricks.(http://www.geofex.com/Article_Folders/mosswitch/mosswitch.htm)
more here (http://www.maxim-ic.com/appnotes.cfm/an_pk/636)
What is the best way to add a 9V wall wart to my fuzz clone? What can I add interms 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 acrosssupply, on the effect side.
Phillip Marshall contributed even more ideas! (http://www.diystompboxes.com/pedals/ps.html)
How do I put jacks for 9V adaptors on my pedals?
JD did all the work here:
Effects Power Switching and Adding a Power Jack.(http://www.generalguitargadgets.com/index.php?option=content&task=view&id=178&Itemid=200)
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 theinput 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 stereojack). For the output, you use a mono 1/4" jack and the tip lug of the jack is connectedto your circuit's output signal and the sleeve lug is connected to ground. The differencebetween a stereo jack and mono jack is that the stereo jack has 3 lugs (tip, ring andsleeve), 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 inputof 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 reversedpower supply such as the Tycobrahe Octavia or some Fuzz Faces). When the cord isinserted 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 thecircuit off and not consume batteries.
In the above picture, do not assume that the lugs shown are connected to the nearestclosest 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 theplug) is on the other side of the jack. When in doubt, use your multimeter to testcontinuity.
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 ReAnnylon body ones (excellent choice, that). Mouser has both. (b) buy the white nylonbushings that Mouser offers. These fit a 1/2" hole and have a 3/8" hole for a standardjack.They're used a lot in isolating input jacks for tube amp hum reduction.
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 theguitar plug is removed. You can see this method of wiring on a number of DIYsites.
Tip, ring, what lug does what?
Question: All effects circuits have an in and an out.. which lugs do these go on on thejacks?
The signal of the circuit goes to the tip of the jack. The ground of the circuit goesto the ring of the jack. So the input to the circuit goes to the input jack tip lug andthe output of the circuit goes to the output jack tip.The ground of the circuitconnects to the sleeve lugs of the jacks.
Does the DPDT/3PDT turn the power on and off? No. If you wire your stereo inputjack like described in this FAQ, power is not used when the pedal is unplugged. Power isused whenever the pedal is plugged into the input jack. The DPDT or 3PDT only workson the signall (with the exception of the LED if used) and does not switch the power onand off.
TRUE BYPASS AND SWITCHING
Bypass - What is true bypass and what is a DPDT switch?
Read this excellent article by R.G. Keen on bypass methods. (http://www.geofex.com/Article_Folders/bypass/bypass.htm)
Also check out my simple Elementary Bypass Article. (http://www.diystompboxes.com/pedals/articles/elbypass.html)
Bypass - How do I wire a DPDT switch?
Check out this picture. (http://www.diystompboxes.com/pedals/DPDT.gif)
Bypass - I have a DPDT but I want to use a 3PDT instead; there are more lugson the 3PDT, how do I do this?
Check out how to go from DPDT to 3PDT. (http://www.diystompboxes.com/pedals/images/DPDT3PDT.jpg)
Bypass - How do I wire a 3DPDT switch with LED?
There are several ways depending on whether you have a "standard" negative groundcircuit (most circuits are) or a positive ground circuit (like the Fuzz Face orRangemaster). Positive ground circuits have the RED wire from the battery connectedto ground which is opposite from most "standard" guitar pedal circuits.
For the standard circuits: standard wiring (http://www.diystompboxes.com/pedals/images/3PDTwiring.jpg) and alternate (grounded input wiring)(http://www.diystompboxes.com/pedals/images/3PDTbwiring.jpg) The grounded inputwiring is probably better since it grounds the circuit input when in bypass mode.
For positive ground circuits: standard wiring (http://www.diystompboxes.com/pedals/images/3PDTPNPwiring.jpg) and alternate (grounded input wiring).(http://www.diystompboxes.com/pedals/images/3PDTbPNPwiring.jpg)
If you want to omit the LED, simply ignore the middle set of lug connections and omitthe resistor and LED.
Also check out this simple page on bypassing: Elementary Bypass.(http://www.diystompboxes.com/pedals/articles/elbypass.html)
Bypass - Where do I purchase a DPDT or 3PDT switch?
Support DIYStompboxes.com by ordering from the store(http://www.diystompboxes.com/cart/)
For DPDT, order from Small Bear Electronics. (Carling 316)(http://www.smallbearelec.com/StoreFront.bok)
Bypass - What's the deal with the cheaper switches I see available... can I usethem?
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 outanytime if they fail (and most cheaper switches seem to fail). For gig use, I recommendCarlings. 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. Ihave found them to be reliable as the Carlings I have and much cheaper. I make themavailable for a reasonable price. (http://www.diystompboxes.com/cart/)
Bypass - I have an Ibanez Tube Screamer and the switch broke, what can Ireplace it with?
From CJ Landry: The part is made by E-Switch with the part number TL1100 and theMouser P/N is 612-TL1100. I have been using this part for a long time when replacingthe 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 differencebetween these switches is the square top (on the plunger). The size seems to differbetween the E-Switch part and this Mountain Switch part. I have not looked at detailedspecs for each switch, but would try the switch which has a longer operating life. This isthe number of switch actuations it can handle before it fails. They both work fine and Ihave no personal preference.
Bypass - have any info on relays?
Yep, GEOFEX.COM again, Relays for Switching Audio Signals (http://www.geofex.com/Article_Folders/relays/relays_for_switching_audio_signa.htm) and Remote relayswitching. (http://www.geofex.com/FX_images/relays2.gif)
DIODES
Diodes are polarized similar to electrolytic capacitors; there's a positive and negativeend. The cathode is the negative end of the diode and the anode isthe positive. Themain thing for you to remember is that you need to orient the diode correctly with theschematic.
LED is a light-emitting diode.It has a cathode as well and it is usually marked with a flatside or dot or in some cases a groove in the LED. Read more about different LEDs.(http://www.firstpr.com.au/rwi/dfish/leds.html) Sometimes there is a longer and shorterlead. 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 sametype look similar in size. The size grows and lead thickness grows with increasingcurrent handling. Most diodes have a band at one end which is the cathode and manyhave a part number stamped on them. Diodes can look similar but may be completelydifferent!!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 partnumber, black bands with part number, multiple coloured bands and no partnumber.Power silicon: 0.6V, high currents, slow, usually black plastic with silveror whiteband and usually a part number.Power silicon-fast: 0.6V, high currents, fast, look sameas Power silicon.Small Signal Schottky: 0.35V, look like small signal silicon andzenersLED: 1.8V, unmistakeable, different colours available.Zener: 0.6V one directionand zener voltage in other direction,look like small signal diodes but are often colouredwitha part number stampedSmall diodes without part numbers are very hard to identifyexactly but are usually small signal silicons or maybe zeners (if it has a number like 5Bor 0A (for 5V, 10V) stamped on it).
How can I change the kind of distortion I have - or make it more fuzzy usingdiodes?
Read this detailed message from Mark Hammer. (http://www.diystompboxes.com/pedals/mhdistort.html)
When should I use silicon or germanium diodes?
Read this detailed message on diodes from Mark Hammer.(http://www.diystompboxes.com/pedals/diodes.html)
How do I wire a FET as a diode?
See here, (http://www.elixant.com/~stompbox/smfforum/index.php?topic=38581.0) andhere. (http://www.diystompboxes.com/wiki/index.php?title=Simplemods#Simple.2C_Easy_Mods.2FTips_.26_Techniques)
Anything more on diodes?
Doug Hammond pointed out this link: The Unusual Diode FAQ.(http://www.avtechpulse.com/faq.html/)
What is a low leakage diode and how can I find one?
Check out this thread. (http://www.diystompboxes.com/smfforum/index.php?topic=16851.0)
What is a zener diode?
Check this out (http://en.wikipedia.org/wiki/Zener_diode)
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 bethe collector (C). If the arrow points away,it's an NPN transistor. If it points in, it's aPNP.
Once you have identified the lines on the schematic, you need to identify the pinouts onthe transistor and match them to the schematic. Refer to the diagram that comes withthe transistor . Lots of transistors use standard package types. Some transistors haveunusual pinouts so always checkthe diagram or obtain a datasheet on the transistor.
This picture shows the FLAT side up of the transistor. You will often see this picturein 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, theyare 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:
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 arevariations in pinouts and variations of T092 etc... Check your datasheet, whichdescribes the pinout of your component.
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 (forsearching) and type in the transistor number.If there is a replacement made by NTE, itwill be shown and you can look at the data sheet if it's online. Since NTE and ECG sharethe same numbers, you should be able to find either NTE or ECGparts at your localelectronics store. Usually these replacements will work fine. Only in very specialcircumstances will the replacement parts fail to work.
Here's a thread on replacement transistors for NPN and PNP transistors and FETs.(http://www.diystompboxes.com/smfforum/index.php?topic=51309.0)
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 (forsearching) and type in the transistor number.If there is a replacement made by NTE, itwill be shown and you can look at the data sheet if it's online. On the bottom of the pagewill be a picture of the pin out. IN MOST CASES, the pin out will be exactly the same asthe 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 orECG 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]
Here's another link to an information resouce on transistors(http://www.americanmicrosemi.com/products/specs/Transistors.phtml)
Misc - What is germanium? Where do I find germanium transistors and diodes?
Germanium is a metallic semiconductor and early transistors and diodes were madefrom it. You can read about the history of the transistor here.(http://ourworld.compuserve.com/homepages/Andrew_Wylie/history.htm) Some earlycircuits like the Fuzz Face and Tone Benders used germanium transistors. You can findgermanium transistors from NTE as well as other electronic places. Small BearElectronics (http://www.smallbearelec.com/StoreFront.bok) and my store(http://www.diystompboxes.com/cart/) offers matched transistors for building thesecircuits. The typically used germanium diode, the 1N34A is available from my store.(http://www.diystompboxes.com/cart/)
Transistors - Can I just stick a germanium transistor instead of silicon in acircuit?
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 Ihave to do this?
No, you don't have to match them, but the circuit may not sound as good. It has beennoted that matching transistors in the Fuzz Face could give you that elusive sound thatthe highly sought after Fuzz Faces had. GEO has a great article that explains this andmost boutique pedals carefully match their transistors by hand. Small Bear has a greatarticle as well! You can do this too. Just buy a ton of transistors and measure each oneuntil 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 Small BearElectronics (http://www.smallbearelec.com/StoreFront.bok) and order a pair.
Courtesy of Jack Orman:Since the supply of 2N388A transistors have been depleted at Parts Express, Ithought I'd post a few alternate devicesthat they carry that can be used for F-F construction. Any of the below partsshould be suitable and are less than $1each. The last one is spec-ed a little weak but would likely be okay. The first one isa good sub for the 2N388A.Part No. Type Hfe Price2N1306 NPN 100 $ .952N1308 NPN 150 $ .752N1309 PNP 150 $ .752N1373 PNP 60 $ .95The NTE101 is another choice:
http://www.nteinc.com/specs/100to199/NTE101.htmlI'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 theywere 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. Itworked fine for my Fuzz face and Tone Bender.... Very nice! (Note, this doesn't work forevery circuit, particularly high-gain circuits, but it's worth a try) For PNP to NPN do thesame. 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? Ihave 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 Debugging page,(http://www.diystompboxes.com/wiki/index.php?title=Debugging) especially the sectionon bias problems.
What about biasing a silicon transistor?
Check out this page. (http://www.interq.or.jp/japan/se-inoue/e_dance26.htm)
Also check out the EMF (http://diystompboxes.com/analogalchemy/emh/emh.html) for agreat calculator to use when biasing a transistor.
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 gainthat I've run into is "Practical Transistor Circuit Design and Analysis"by GeraldWilliams; 1973 McGraw Hill, TK7871.9.W53, ISBN 0-07-070398-1.
What about buffers?
Check out this page (http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/buffer.html)
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 forany silicon PNP uses.
The 2N5087 is also the PNP complement of the 2N5089.
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. Youcan purchase NPN and PNP transistors from the store. (http://www.diystompboxes.com/cart/)
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 findthe J201....
From Jack Orman:
This is a recurring question eventhough the information was in the Mini-Booster articleat AMZ From the article: "The NTE458 usually has more gain than the J201, and the2N3686 can provide gain of 500. The 2N5457, MPF102, and 2N3819 will produce lessgain. 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 sideup, 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 generalindicator of gain as well... Yfs of 1000 is low gain, 3000 is moderate and 12000 issmokin'" (Thanks to Jack Orman for this tidbit!)
Where can I get a simple explanation about biasing a FET as an amplifier?
Read about a FET amplifier here at Graham Knott's page.(http://homepage.ntlworld.com/g.knott/elect247.htm) (Thanks Mike B.)
Here's a great thread re: FET biasing
FET biasing calculations thread (http://www.diystompboxes.com/smfforum/index.php?topic=57219)
Vishay FET app notes (http://www.vishay.com/fets-small-signal/ssfanp/)
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 BS170has a different pinout. The 2N7000 is S G D flat side up, left to right and usuallyrequires 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 usesince 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 atwww.techamerica.com and Future(1800-655-0006). The NTE and ECG FETs should beat most major electronic stores. The 2N series can be found at www.mouser.comas wellas all the other places I list. (http://www.diystompboxes.com/pedals/buy.html)
Here's a cool link re: FETS (PDF) (http://nutsvolts.com/~downloads/fetjul.pdf)
What's a good meter I can purchase?
Check out this thread for some suggestions. (http://www.diystompboxes.com/smfforum/index.php?topic=50673.0)
How do I measure transistor gain?
The easiest way is to get a multimeter that can measure transistor gain (hFE). Thecheapest one I have found is from Hosfelt (http://www.hosfelt.com/en-us/dept_651.html): 9202- Multimeter, just $12.95.
What is hFE?
Here's a thread on hFE (http://www.diystompboxes.com/smfforum/index.php?topic=57652.0)
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 1/2watt resistors but they take up more space and do not provide any benefits. Yes, youcan 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 multiplierletter.This prevents the possible loss of the decimal point in transcribing data. Forinstance, 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 1000picofarads.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. The EMH(http://diystompboxes.com/analogalchemy/emh/emh.html) has a calculator for this.
I recently read somewhere that using carbon composition resistors in an effectcircuit would help to create "brown sound". Are carbon comp. resistors reallybetter to use for audio circuits?
Here's a nice article written by R.G.on carbon comp. resistors.(http://diystompboxes.com/pedals/rgccmp.html) Here's another thread on resistors(http://www.diystompboxes.com/smfforum/index.php?topic=52937.msg401056#msg401056)
Is there a visual calculator I can use to figure out my resistor values? Yep, checkout the EMF (http://diystompboxes.com/analogalchemy/emh/emh.html)
OP AMP
I need to find that JRC4558 chip that's in the TS-808, I heard you can get themfrom old radios and other voodoo sources!
Yes, you probably can. Or, you can buy the current chip that sounds the same as theoriginal- 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, thenA, 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-mountpackage.
Sometimes the different package material implies different operating temperatureranges.
Basically you are safe with any of these except D. For Audio projects usually thecheapest 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
In this case, you need to lookup the datasheet for the op amp. Note that you can use aTL071 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 ampssuch as the TL072, JRC4558:
Dual Op Amps have this pinout (TL072, JRC4558).
Referring to the IC in schematic picture above, the wire going into the minus sign is theInvertedInput/pin 2. The wire going into the plus (+) sign is the Non-InvertedInput/pin3. Vcc refers to the Vcc (+) input /pin 8. The groundgoes to Vcc(-)/pin 4. The wireexiting the IC in schematic is the Output /pin 1. Since the TL072 is a dual op amp, thereare two sets of Input and Outputs. Sometimes circuits will use both amps (inputs andoutputs), sometimes it will use only one set. In both cases, Vcc(+) and Vcc(-) will haveto be connected. Vcc(+)goes to positive power. Vcc(-) goes to ground. If only one of theop amps are used, the other set of inputs and outputs can be left disconnected. In someschematics, the Vcc(+) (power) and Vcc(-) ground will not be shown. This does notmean you don'thave to connect these pins, you have to; the schematic writer isassuming you already know this..
Let's look at a typical circuit using a popular chip, the LM741. This chip was used in theMXR Distortion+, Dod Overdrive and many others. Although widely used,it's a noisychip. You can replace the chip with another lower noise op amp like the TL072 if youare building your own circuit. Note if you are modding an existing pedal, use the TL071- a direct chip replacement.
example circuit using 741 chip <-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 LM741pinouts to the TL072.
TL072 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 whensoldering and you can always substitute a different IC later. For example you can try anRC4558 or TL082 etc...
Here's a link to some op-amp basics. (http://ourworld.compuserve.com/homepages/Bill_Bowden/opamp.htm#opamp.gif) Here's a link to a thread re: op amps(http://www.diystompboxes.com/smfforum/index.php?topic=53224.0)
Here's a TI article (PDF) Called Op amps for everyone by Ron Mancini(http://focus.ti.com/lit/an/slod006b/slod006b.pdf) Good Read!
a thread about VREF and bias currents of opamps. (http://www.diystompboxes.com/smfforum/index.php?topic=60335.0)
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'sflexible 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. (Thelarger 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 strandedand solid core - very nice. In general solid core will stay where you want, but will notlike being moved and can break easily. Stranded is much tougher but resists bends andwill generally not look as "neat" in an enclosure. Ifthe circuit is being mounted in anenclosure and will not be removed- solid core is ok. If the it's going to be moved at all, Irecommend stranded wire or the hookup wire mentioned above from SmallBear.
I live in another country, what's a good place to order from?
Try FutureElectronics (http://www.futureestore.com/eStore/default.aspx/) - a globalcompany 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 and151-TO-18320G. Most 3 pin sockets will work fine. Most times, I simply cut up an 8pinDIP now. (http://www.diystompboxes.com/beginner/build/build%20004.jpg)
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 GeneralGuitarGadgets.com (http://www.generalguitargadgets.com/index.php?option=content&task=view&id=141&Itemid=154)
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 youwant a solution that's cheap but a little harder to work with,check out electrical outletjunction boxes. Thanks to Jack Orman for the tip.
I have been using the 1590BB Hammond box that R.G. recommends. It is so great tobuild into a box that is sturdy, has enough room and looks good. SmallBear Electronicsis now offering the 1590BB for a very good price!. For a smaller box, check out thesealuminum 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 powersupply and measure the amperage.
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 batterysnap. On the + contact of the battery, touch the red probe and on the free contact of thebattery 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 redprobe. Read the DC measurement on the meter.
How do I measure inductance?
You need a meter that can measure inductance. Here's one.(http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-570)
Testing - I'm testing out a pedal I made and I want to test it out with a functiongenerator. What kind of signal should I use?
From Zachary Vex. (http://zvex.com/) Put the output of the function generator on ascope, set it for around 400 Hz, sine wave output, 100 mV peak-to-peak, and use a 47kresistor in series between it and the input to your pedal. you can increase the output toas much as 1 V peak-to-peak safely, i think, and you should monitor the output of thegenerator on a meter or with one trace on the scope while you monitor the output of thecircuit 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: Basic Testing of Semiconductor Devices. (http://www.repairfaq.org/REPAIR/F_semitest.html)
Can I test a capacitor with my continuity function?
You cannot test a cap with the continuity feature. The continuity feature of most meterswill only beep when there is very low resistance.
Check out the Electronics Math Helper. (http://www.diystompboxes.com/analogalchemy/emh/emh.html) VERY COOL!
Check out Marcelo's Bias Calculators (http://www.diystompboxes.com/biascalc/)
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, youget
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 infarads 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 capand the emitter bypass cap. The -3dB point is determined by the "worst" of theseformulas.
For ƒlow due to Cin, you need to know the signal source impedance and the inputimedance of the amplifier itself. Not a trivial excercise, so I won't go down that path,unless you really want me to!
See the Debugging page in the Wiki (http://www.diystompboxes.com/wiki/index.php?title=Debugging)
How do I debug and fix my effects?
Check out GEO's FX Debugging page (http://www.geofex.com/fxdebug/fxdebug.htm)and mine. (http://www.diystompboxes.com/pedals/debug.html)
I am getting a whine - like feedback but high pitched when I turn the drive allthe way up...how can I fix this?
You probably are running the leads of the input and output too close or they are toolong. Keep the leads as short as possible when laying out your box. You may also wantto consider using shielded wire. To do this, shield the wire on one side only and thenconnect 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 signalswitching and use the "inner" connections for LED switching.
Fixing Power Fried Pedals
Check out the thread on this. (http://www.diystompboxes.com/smfforum/index.php?topic=55003.0) Great reply from R.G.
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 jackswitching. You can get pops when switching the relatively high LED current even ifyou have pulldown resistors on both input and output caps.
The culprit is ground noise. The ground noise happens when the sudden startand/or stop of current in the LED makes the signal ground voltage changesuddenly. +9V decoupling may not help, and may make it worse.
The ground noise comes from our friend, the stereo jack ground switch. If yourjack 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 highenough to make a noticeable pop when the LED current starts and stops.
This sudden transient is worse with mechanical switches because they really do gofrom fully off to milliohms of resistance in zero time when the metals contact. Thesudden "ground bounce" can flow right into the input of your effect, and it doesn'ttake much to hear a pop from the input of a gain-of-a-zillion MegaBlaster.
Also another thread on popping. [See the post by R.G. http://www.diystompboxes.com/smfforum/index.php?topic=68210.0]
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 thepedal.
(3) Use the GEO scheme for cold-switching +9V by using a PNP transistor with it'sbase tied through a resistor to the stereo lug on the input or output jack, and thebattery minus tied directly to the board. The PNP transistor only lets +9 throughwhen its base is pulled down by the plug in the jack, but this current does notchange 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, muchsmaller.
See the power supply switch in the Neutron filter at GEO or at GGG, or see thepositive 9V switch in [1] (http://geofex.com/FX_images/oaspltr.gif) for how to hookup the PNP.
original thread on popping. (http://www.diystompboxes.com/smfforum/index.php?topic=23743.0)
Measure for DC
See this thread (http://www.diystompboxes.com/smfforum/index.php?topic=69693.0)
PEDAL SPECIFIC
Negative Ground with PNP Fuzz circuit????
Here's a WARNING about converting a positive ground circuit to negative ground. (asin a Fuzz Face) (http://www.diystompboxes.com/smfforum/index.php?topic=44955.msg327858#msg327858)
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 characteristichigh-frequency response and gain. Usually the higher the gain of the transistor themore high frequencies it can amplify. Try a 2N5088 or 2N5089 for a start. 2N2222can work but will be duller-sounding.
2. Increase the input impedance of the circuit. You can do this by changing thebiasing resistors on the base of the transistor, keep the same ratio (on an LPB-1/2it's usually 10 to 1, 470K to 47K - try 1M and 100K) and also by inserting a resistorin 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 earsunless you're using it for bass. Try a .047 or a .033.
Any tips for a Big Muff modder?
Check out this post from JCM: JCM on Big Muff mods. (http://www.diystompboxes.com/articles/bigmuffjcm.html)
I want to mod my wah, any information on this?
Required reading on wahs (http://geofex.com/Article_Folders/wahpedl/wahped.htm)
This thread is very informative re: inductance (http://www.diystompboxes.com/smfforum/index.php?topic=39546.0)
I finished building a Foxx Tone Machine (FTM) and it sounds great but I amhaving problems figuring out how the full wave rectification happens in thecircuit. 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 Octaviamakes two versions, one following the input signal and one inverted in polarityfrom the incoming signal. The diodes allow only the currently-positive version toappear at the output by each letting signal through only when the signal feeding itis 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 biasedslightly on by the resistors around them so that the effect of the diode forwardvoltage is largely canceled out. But each diode merely conducts when its anode ismore positive than its cathode, just as in the transformer case. The diodes think it'sthe 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 filterthat will roll off highs by 6db/octave starting from around 475hz (when the pot isat maximum resistance of 100k) and tunable up to 32khz (when the pot is set tominimum resisatance and the filter is determined by the cap and 1.5k fixedresistor). Some folks, myself included, find the upper range of the filter to berelatively useless, and so have changed the filter cap from .0033 to .0047 (orlarger). With a .0047uf cap, the tuning range shifts to 334hz-22.6khz, which is a bitbetter.
But lets look at the bigger picture...
The purpose of such hi-cut filters is to take out the fizziness and impart somewarmness. Because the filters have such a shallow slope (only 6db additionalrolloff for every octave higher), you have to set your rolloff frequency quite low tohave 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 accommodateaircraft that needed a long running start to attain liftoff? Fortunately we canshorten the "liftoff time" by opting for a slightly more complex filter withoutdrastically complicating or impairing the circuit.
If one uses a dual-ganged pot as the tone control, it becomes possible to create asteeper filtering action by having 2 poles (12db/octave rolloff), so that you canhave double the reduction in high-end fizziness without having to remove too muchof the "body" of the sound. Moreover, the opportunity to cut high end more sharplymeans you don't really need as much tuning range to achieve a noticeablevariation in tone.
The Rat circuit assumes a total series resistance range of 1.5 to 101.5k. We couldduplicate that but as noted, we probably won't need that wide a range. I'm going toshoot for a tunable range of 3.3k minimum resistance for each filter section, to amaximum of 53.3k. In tandem with a .0033uf cap for each section, this gives a12db/octave filter that can be tuned from a rolloff point of around 900hz to around14.6khz. If you like it slightly darker, change the 3.3k resistor to 4.7k and yoursweep 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 andwork with a dual 100k pot (even RS sells them!). The two pot halves are wired upidentically as variable resistors (rheostat) in series with each other, so that at oneextreme their combined series resistance adds up to 200k or thereabouts (andobviously 0 ohms at the other extreme). You want their combined resistance to maxat 100k, so put a 100k resistor in parallel with each pot half to achieve 50k per potsection. The series resistor doesn't really care which side of the pot it goes on aslong as turning the pot produces the same type of resistance change for eachsection. So, one fixed resistor can go on the input to pot half A and the other on theoutput 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 seriesresistances (keeping in mind the location of your fixed series resistors).
This change should produce no decline in max output level (maye even a slightincrease 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 anothermatter.
What's the deal with the limited drive range on an MXR distortion+ clone Imade?
Check out this thread regarding the distortion control. (http://www.diystompboxes.com/smfforum/index.php?topic=47202.0)
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 coverpretty much all the holes you need to drill. I bought the smallest size bit (1/2" max) andit worked for everything up to footswitches. About $20 in my local store.
For the stomp switch 1/2" is OK and for the jacks it depends on the style:
For switchcraft types is 3/8" to 7/16" (other brands may be a little more or a little less,but within the range)
For plastic types (Marshall style) is 7/16" to 1/2"
What's a low-cost soldering iron I can get
This one is very low cost with replaceable tips. (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=370-010)
For a little more, you can get the Weller WP-25 iron (http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=372-110) and get different tips.(http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=372-127)
What's a low-cost soldering station I can get?
This Weller WLC100 station is easy to use and works great.(http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=372-120)
Here's another that the forum members like (AUTO-TEMP 379).(http://circuitspecialists.com/prod.itml/icOid/7501)
How do I measure inductance?
You need a meter that can measure inductance. Here's one.(http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=390-570)
How does an oscilloscope work?
Check out R.G.'s response. (http://www.diystompboxes.com/smfforum/index.php?topic=74192.msg602821#msg602821)
MISC
What matters, what doesn't
Here's a link to a thread from our forumers that explains what matters to them andwhat doesn't when starting out. (Complete with colorful posts!)
What matters, what doesn't.... (http://www.diystompboxes.com/smfforum/index.php?topic=23386.0)
Check out this thread from the forum (http://www.diystompboxes.com/smfforum/index.php?topic=59855.0)
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 connectedso that the components are next to each other with the same leads connected to eachother.
How do I put 2 components where there is one presently? I heard that I can put 2diodes instead of one on my board and it will sound better? How do I fit 2 diodes orcomponents 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 thediodes into a tight space.
Bypass - I get oscillation/squealing from my distortion when it's bypassed. Howdo I stop this?
Your pedal has such high gain, that the input needs to be grounded when the effect isbypassed. Jack Orman's alternate wiring method (http://www.diystompboxes.com/pedals/grndin.JPG) does this. If you need an LED+input grounding, use R.G. Keen's Millenium2 bypass with extensions. (http://www.geofex.com/Article_Folders/Mill2extn/mil2plus.htm)
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 canadjust this up or down --higher values will start to cut treble. use the lowest value thatworks.
From Zachary Vex: (http://zvex.com/)
Mount the pc board as close as you can physically to the metal box. this will serve as aground plane to reduce the heterodyning that can pick up rf. don't let the input andoutput wires cross... make sure the layout doesn't allow input and output connections toget too close to each other. if you can, solder in ground connections around (near) thesensitive 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 (internalrf oscillation in the circuit beating against rf from radio stations) you can get rid of itthrough 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 theboard 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 andend of your circuit. This is implemented as a 1 meg resistor from signal to ground. Justput one at the beginning of your circuit board (before the input cap or start of circuit ifno input cap) and another at the end (after the output cap or end of circuit). Look at themany GEO layouts (http://www.geofex.com/) if you need to see a layout using theseresistors. 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 usinga DPDT?
Yes! Check out the GEO Millenium Bypass. (http://www.geofex.com/Article_Folders/Millenium/millen.htm) I have used the Millenium Bypass with bothMPF102 and J201FETs. The J201 worked well with the white blinking LEDs I got from Radio Shack. TheMPF102 worked ok with the Red LEDs I used. Look at the very clear diagram(http://www.diystompboxes.com/pedals/dpdtled.JPG) that Jack Orman wrote for hookingup the circuits. If you make the Millenium Bypass, the wire labeled To Switch connectsto the DPDT switch. The +9Vdc connects to the plus terminal of the battery or any +9Vconnection on the board. The Ground wire goes to any ground on the board or theground on the jack. The rest of the DPDT is hooked up like the diagram(http://www.diystompboxes.com/pedals/dpdtled.JPG) 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 ordecrease the value to make it brighter.
Muzique.com LED Calculator (http://www.muzique.com/schem/led.htm) (Thanks Jack!)
LED Series Resistor calculator (Bill Bowden) (http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm)
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 stickcomponents into the holes. So to connect a resistor to a capacitor, all you do is stick theresistor lead into a hole, then the capacitor lead into another hole that is "wired" to thefirst.It's relatively easy to test circuits on a proto board because you can easilysubstitute different components. The drawback is that the proto board layout can endup 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 havethem.
From R.G.:
Most JFET amps, like most triode and pentode amps don't need an input blocking capunder most conditions.
This is because the correct bias voltage for most of these circuits is with the gate (orgrid) at zero volts and the source (or cathode)a few volts higher. JFETs, triodes, andtubes are -depletion-devices which means that if you do nothing to them, they conductlike mad. Bias for all of these devices involves holding the gate/grid-lower- than thesource/cathode to turn them partially off. Thisis most often done by holding thegate/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 currentincreases through the drain/plate. This same current has to flow through thesource/cathode resistor,so it pulls the source/cathode up above ground, reverse biasingthe gate/grid a little. Eventually the source/cathode rises enough that the voltagebetween it and the gate/grid is just right to keep that amount of current flowing and soit stabilizes at that current. It's so-called self biased.
This is different from bipolar transistors and enhancement mode MOSFETs. Thesedevices are normally off, and you have to do something to the control electrode to makethem turn on a bit.
In any case, the correct voltage for many JFET and tube circuits is zero volts DC on thegate/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 playthrough my boom box etc...
You can. Check out the Marshall type cabinet simulator. (http://www.diystompboxes.com/pedals/schems/msim.jpg) This does not replace a miked amp,but is usable and soundsgood 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 'tilescriber'which is just a knife sized handle with a tungsten carbide point stuck on. Youjust clamp the board with a metal edge on it &scrape away heavily a few times, thensnap on the scoreline. OK it's trivial & obvious maybe, but I tried to cut them in abandsaw, 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?
Read GEO's article on this. (http://www.geofex.com/Article_Folders/howtrace.htm)
What's an easy-to-use PCB program?
I have heard Easytrax (http://www.ece.uiuc.edu/eshop/pcbdesign/) is everything weneed for making PCBs.
What can I use to view/create PDF files?
You can write PDF files with Ghostscript (http://www.cs.wisc.edu/~ghost/) for free.
What about layout software?
Check out the DIY Layout Creator Software (http://www.diystompboxes.com/smfforum/index.php?topic=44838.0)
Where can I check out patents? I would like to see what others have donebefore....
Easiest is to cast them from casting resin or sculpt them from Bondo auto body putty orSculpy plastic clay. Find some plastic knobs you don't like, and break the plastica wayfrom 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 threadedhole free and insert it into the set screw hole. Wouldn't hurt to stuff the shaft hole full,
Then mix up the body putty, and start building up the knob body. As the stuff cures, itgoes through a "cheesy" phase where it's really easy to cut and shape. Once it fullycures, it is hard and solid, can be sanded to avery smooth surface or sculpted by aDremel with a burr on it.Then paint.
For the Sculpy (FIMA is anothertrade name) just sculpt the stuff on the insert likemodelling clay, and bake it according to the directions when you get it right. Not asdurable as Bondo, but easier to work.
If the design is fairly simple,make a wax model of the knob, pour plaster over it to makea mold,and then melt out the wax. Pour in catalyzed casting resin until the level justsupports the insert, let it harden a bit to hold the insert in place, then do another pourto complete the knob.As with the bondo, use parafin to keep the setscrew hole and shafthole free of the casting material and melt it out later.
Other people must have asked a ton of questions about all sorts of stuff beforeright???
Yes! Look at this FAQ archive!!! (http://www.harmony-central.com/Guitar/Faqs/) fromHarmony Central!
How can I make a Triangle Knob Big Muff? Where's the schematic? Where's theschematic 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 itspedals. Stories from original buyers of various versions of the BMP and other EH pedalsindicate 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 postedthem. The "swell" circuit on the Prescription Electronics pedal is exactly the samecircuit as a 1968(about) article in Popular Electronics by Anthony Leo about building anentire distortion circuit, but it's modestly mis-used to take the output at a place that hasa DC level that starts high and drops to about zero over a bit of time. It's also DCcoupled 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 notcarrying signal. Since it's a one-size-fits-all kind of thing, it only works right for ampswhich have
(a) DC input coupling(b) about a 2V range before being pushed into saturation or cutoff on theinput
(c) NO DC coupling to the speakers!!! Do this on a solid state DC coupled andand you'll fry a speaker. Many tube amps have no input coupling cap, about a2V range, and are AC coupled, so they work OK. SOME solid state amps areclose 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. Olderbatteries don't make the happy-accident level changing work right. When itworks, the volume on each note starts quiet and ramps up to full level, kind ofan attack delay. The Experience Pedal is just the Foxx Tone Machine circuitfollowed 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 passessignal when on and off but no effect. Do you guys think it is the rare mn3005delay/chorus IC gone bad???
From Mark Hammer
The chip may actually be okay, but you may need to do an adjustment to find out. Thereshould be a trimpot near the MN3005. It provides a DC bias voltage that the audiosignal has to ride on in order for the chip to pass the signal through. Sometimes, thetrimpot 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, slowlyturn it while you play or feed an audio signal in to the MM. At some point, you shouldhear the audio signal if the problem is as I describe.
Thread about soldering and temperature (http://www.diystompboxes.com/smfforum/index.php?topic=51215.0)
What kind of solder should I get?
For fine work, you get thin solder usually 60/40. However check out this thread fromthe forum. (http://www.diystompboxes.com/smfforum/index.php?topic=18616.0) Try out63/37.
Other misc...
Inductor testing and values (http://www.diystompboxes.com/smfforum/index.php?topic=51510.0)
DIY Layout Creator is excellent for creating circuit board layouts! (http://www.storm-software.co.yu/diy/index.php?project=software)
DESCRIPTIONS/SOUNDS
What are these boxes? What's a delay, phaser, phasor, etc...?
Check out HarmonyCentral's effect description page (http://www.harmony-central.com/Effects/effects-explained.html) or R.G.Keen's effect descriptions page.(http://www.geofex.com/effxfaq/fxdescr.htm)
What did these things look like?
Check out this book The Stompbox by Art Thompson. (http://www.amazon.com/exec/obidos/ASIN/0879304790/aronwebpage) Here's another place(Stompnet)(http://www.geocities.com/~stompnet/Main/Gallery/gallery.htm)
Can I really make something that looks good?
Well, check out some pictures from the forum! (http://www.diystompboxes.com/smfforum/index.php?topic=36392.0)
What do signals look like?
Check out this site (http://www.doctronics.co.uk/signals.htm)
You've got so many schematic links here. I don't know what these stompboxessound like? Which one's should I try?
Yes, there are a lot of schematics. Someone obviously thought the stompbox soundedgood enough to document... Here is a link to Harmony Central's Effects database.(http://reviews.harmony-central.com/reviews/Effects) Users write in and voice theiropinions. Another way is to look at what stompboxes custom manufacturers arebringing back. Stompboxes like the Colorsound line, the Big Muff etc... If they arebringing it back then it can't be so bad.Try the most popular ones and then try the moreesoteric ones.Check out www.tonefrenzy.com (http://www.tonefrenzy.com/audio_demo.html) for great samples that you can listen to. There is a number ofsamples on AMPAGE. (http://sounds.ampage.org/) DIYStompboxes.com forum memberBasicaudio has a web page of samples as well. (http://www.mrdwab.com/john/soundclipspage.html)
THE FORUM
Give me more to read. I want to learn more!
Check out the FAQ forum (http://www.diystompboxes.com/smfforum/index.php?board=10.0)
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 theirposts. You can search by poster name.
If you see someone posting valuable info, do a search on all the posts they have made inthe last year or so.
How can I add something to this FAQ
Send me suggestions/links etc.. via email: FAQ Suggestions.(mailto:[email protected])
Retrieved from "http://www.diystompboxes.com/wiki/index.php?title=Frequently_Asked_Questions_(DIY_FAQ)"
This page was last modified on 9 October 2012, at 20:42.
