Component Part Equivalents

[Pakaloabob]

I would like to know if anyone would be kind enough to give me some examples of parts that can be swapped, or help direct me somewhere I can find such info. If possible I would also like to know if anyone has part #s for Mouser or Digikey for parts they have used.
I am new to building guitar effects - have built only 3 so far. I etched the boards, soldered components, drilled and painted enclosures.
While looking at different projects I have noticed many components that are similar between many FX. I have also seen several schematics for the same project on different sites using different components. I am assuming that the different components have similar attributes. This got me thinking that I could buy a variety of transistors, diodes, etc. and try them in my projects. Small Bear offers a "jellybean transistor kit" with several common silicon transistors. However, I have not found any real good resource which compares transistors and their usage in guitar effect pedals.
For example, what diodes could be used in my Dan Armstrong Blue Clipper instead of the 1N914 that I am using? I have seen recommendation to use 1N34A or 1N270 but I am having a hard time deciding the appropriate part from the large stock at Mouser.
I appreciate any help.

[frank_p]

Welcome to the forum!

Parts swapping possibilities depend on the built requirements and on your taste of what the characteristics of the component will give you in a given circuit.

- One of the built requirement is the layout:  Does the part that you are going to swap into is going to fit in the layout you use. One example is the pinouts of op-amps and transistors.  ARE THEY THE SAME AS WHAT YOU'RE GOING TO USE WITH YOUR LAYOUT.
- If the effect is going to be used mainly in the house-lab, you can use sockets in your builds.  If you use sockets for transistors, resistors and caps, be aware that they can disconnect during performance. Measure, Measure and measure with sockets or not,  when swapping: read books, data sheets and TAKE NOTES of your experiment results.
- Put dates and circuit names on your board: what you had built previously can become a mystery latter in you stompbox living life.
- Other requirements are into designs that requires a certain specifications to work correctly.  If you use a conjunction of searches with the effect, the part code (the two on this forum) and the datasheets of the components, you will find a lot of substitutions possibilities that members have tried.  But in most effects, especially distortions, it won't matter that much about if it's going not to work.

If you beguine with fuzzes, overdrives and distortion, in most cases you don't have to worry too much about the specifications at first.  Go with what has been tried and what fits your style.  Search on the forum for opinions.  In most cases if the pinout is correct for the layout: it will give you different sounds depending on the characteristics, and it will be OK.  Op-amps selection (same pinout) will have generally small impact on sound in distortions: I tell that in the sense of: you can experiment without fears.
Transistors: you can get a collection of any transistor (any gain: Hfe or beta) and make a good usage of it, given a pinout or casing style.  From 50 to 300 Hfe of current gain: you can experiment.  If you use a layout check the pinout. And genrally it's no use to use a power transistor for a stompbox....  Be aware that germanium can have a lot of leakage and it can be difficult to do something usefull out of them if they are of too low gain and have too much of current leak.
For FETs be aware that their characteristics can vary all over the map: the tolerances given a given datasheet characteristic can vary A  LOT.

BJT Transistors useable for dirt boxes could be labeled like this: audio preamp, small signal, general purpose, (and more).
Diodes:  Germanium have a lower forward voltage drop (0.3) than silicon ones (0.7), but you can substitute any of them in distortions (with volume variations).  You can also try the LEDs. 

For semiconductors components (diodes, op-amps and transistors): make yourself a list of common popular effects that are made in the DIY "habits" and their components that are present in the available schematics.  Make a list of them with all the other basic components you could need (with resistors, capacitors, potentiometers). Then decide on the budjet you want to spend and the given designs you want to build.

If swapping is your goal, buy a breadboard, measure with what you have, consult datasheets and READ BOOKS and-or the internet.

If comparing swaps is really an interest: be sure to have a multimeter and take readings.

If possible, find yourself a buddy who can have access to HAM radio equipment swaps.  He could help you locate an oscilloscope for very few $$$s.  And a measuring equipment like this is really in valuable in whatever endeavour you are going to take.


Consult the wiki:
http://www.diystompboxes.com/pedals/buy.html

For resistances and capacitors: some don't like ceramic caps and carbon compressed resistors: they can induce noise and hysteresis.  But, if you want to use them, in most case in won't matter.

So you can use everything, most of the cases for basic distortion circuits.

There are a lot of talks about "overdrives" but in general "considerations" are a door that is open to the subject.  Not a barrier.

Electronics in the "distortion area" is way more accessible than most people are willing to admit.
But if you have a particular (specific) goal, that is an other thing.

FHP

[compuwade]

The most common transistors across a whole bunch of effects are the 2n5088 and the 2n5089. The 2n5089 is a lower noise higher gain version of the 2n5088 but either sound pretty close to me. I would say that if you purchase:

NPN Trannies

2n5088 (high gain)
2n5089 (high gain)
2n3904 (Med Gain)
2n2222 (Low 2 Med Gain)
2n4401 (Low 2 Med Gain)

PNP Trannies

2n3906

FETS

j201
mpf102
2n5457

MOSFET

2n7000

then you should be set to build many effects.

As far as the diodes, you can pretty much use any diode, including LED's, for any clipping circuit. All of them sound good, but much different. The most common diodes are:

1N34a
1N914/1N4148
1N400X
RED LED's


If you have these diodes on hand you are set to build most everything that requires a diode.
If you don't have a breadboard I suggest that you buy one. That way you can swap out the different diodes and transistors to get an idea of the difference between each part.

I hope this helps

-Wade

[Pakaloabob]

@frank_p: Thank you very much for the lengthy and informative response. I needed some of that basic general info to make sure I am using the right techniques. I will definitely invest in a breadboard to do some experimenting with my next project. I have also read that IC sockets can be snapped apart to make sockets for components on PCB.

@compuwade: Thanks for the specific list of parts to try out. I have seen many of those components listed for a lot of the effects I would like to build. Nice of you to list the transistors in order of High/Med/Low gain. That is exactly the kind of info I was looking for. Did you find that info somewhere or did you compile the list yourself?

I understand that PNP should not be substituted for NPN. Does the same go for Fets, MOSFETS, etc. Are they classified by L/M/H gain as well?
Are there differences between the 1N400x diodes? Radioshack sells an assortment of 1n400x diodes but the values vary. Is it worth having many different varieties of 1n400x diodes to try? I see 1n4001 listed more often than other values. Is there a reason for this?
Are 1n914 and 1n4148 exact equivalents or are there differences?

[petemoore]

  A lady came in, car smokin' and clankin', I checked the oil...no oil..
  She wanted some specific brand. I said ''the motor will blend and mix these into an oil of oily qualities", she mentioned her husband wouldn't like that, hitting the accellerator on the vintage caddilac sayin' she's gonna find the 'right' oil.
  I had no time to explain that the right oil is Any clean motor oil now !
  And custormers who insist on the OEM rubber tires.
  Trick is to know your engine, tires, oil. The OEM's are probably fine and all, but there's almost certain to be tires that:
  Fit the size.
  Ride better, get better G-miles, have excellent all season traction, less expensive and more available.
  For the motor oil, change to whatever is your preference...but never let the oil level drop to where the engine burns up !
 
 

[petemoore]

  Most of the time it's like that, you'll need oil, tires. Find some suitable items, use them, much preferred to being stranded...
  2x4 has a nail in it, but it's the only 10' one around, leaving choices:
  Leave the nail in and cover it with drywall because it won't matter.
  Pull the nail and drywall over it.
  Use the steel stud [although more difficult to attach, if it works it works.
  IOW, using what you got that'll work, works.
  Don't mix polarities up, NPN Neg ground won't work with PNP transistors [unless you reverse the power supply...
  There's almost always a work-around or variety of components that'll work in any one position.
  Mosfet, Jfet, Bipolar Si, Bipolar Ge, all have different bias needs and sound characteristics, can't be swapped pin for pin without alteration [mostly].
  I haven't been able to find 'low quality' components much {I use film capacitors, mostly], though I do prefer the LM741 in a Distortion +.
  Availability, then price generally dictate the parts used in my builds.
  I like used old parts in general, but prefer fresher electrolytic caps, they take longer to dry out.