#1
So last year my brother was taking a load of junk to metal recycling and I saved this old radio from a '68 chevy truck cab. Well just recently I've been poking around at the circuit and I don't think I'll ever get it to work (old leaky oil capacitors, rusted up chassis and tuning stuff) So I decided to just steal parts off of it.

Now being the pioneering (noob) that I am, I decided to build a distortion pedal out of one of the transistors that was in it (I think it's germanium, it's got a metal case and another transistor, power amp transistor, is definitely germanium because I found a datasheet). Anyhow, so I rigged up some 500k pots to play with the bias and what not and well, crap, nothing worked. Then I hooked the battery up backwards (why not?) and WTF?! It works!! And it sounds amazing! haha I don't even know how that works (actually I bet if I swapped the collector and emitter, I could do it with the battery in properly) It must be an NPN and I was guessing it was PNP or visa versa.

Anyhow, does anyone have any helpful words for designing a two transistor pedal? Or is it simply a case of gang two amps together like so:
Powaaaa----------|
| |
| C------------Out
C---------------B-|
Input------B-| E
E |
GND----------|------------------|-----------------

Dang it! Why does it always mess up my text pictures. I guess I'll have to whip out the paint.


(obviously with the right filter caps, biasing resistors and so on)

I might make a little recording of the pedal if I'm not too lazy.
Last edited by LeviMan_2001 at Jun 1, 2010,
#2
any idea on what transistors they are?


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RBY CYOA
#3
I'd love to hear some samples of this
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#4
PNP uses a positive-ground power supply. that's why it worked when you flipped the battery. i.e. the positive terminal of the battery will be grounded. your "+9v" should say "-9v".

you better put current-limiting resistors on the collectors and bases of the transistors. Maybe some Gain resistors and bypass caps on the emitters, and a coupling cap on the input, output, and maybe between the 2 gain stages.

and after all that is done, congrats! you built a fuzz face...
#5
I graduated 6th in my class and everyone who can build in this forum just blows my freekin mind. I mean, I'm smart but you guys are like Stephen Hawking crossed with Albert Einstein whereas I am Fred Flintstone.
Life is about taking risks, as long as the risks aren't too risky.
#6
Quote by Invader Jim
PNP uses a positive-ground power supply. that's why it worked when you flipped the battery. i.e. the positive terminal of the battery will be grounded. your "+9v" should say "-9v".

you better put current-limiting resistors on the collectors and bases of the transistors. Maybe some Gain resistors and bypass caps on the emitters, and a coupling cap on the input, output, and maybe between the 2 gain stages.

and after all that is done, congrats! you built a fuzz face...


Oh yeah, that picture I posted is just super simplified and not even how this circuit is. I've got coupling caps, and resistors and everything. I'll get a sound clip.

And, yeah, it says on the transistor:
DELCO
DS52
F A 274 9G

And there's another one still on the board, along with two more regular plastic case transistors and another shorter fatter round metal case transistor. Anyone got any super old datasheets? Also how do I attach mp3s?

It's way old, probably around 1967-1972
Last edited by LeviMan_2001 at Jun 1, 2010,