Wha…? What is this?

[Transistor-Transistor]

So a while ago my friend asked me to make him a fuzz-wah. I know for a fact I used a crybaby style wah for the actual wah part, but the fuzz... I can't remember for the life of me what the fuzz is based on. My friend let me look at the insides of it last night and I took some pictures of the fuzz board.






So it's obviously janky. However I do know it sounds amazing. Does anyone know what this could be based on? I can't read any of the capacitor values and I think I can faintly read the op amp is UA741

Oh the one thing I remember is the diodes are 1n34.

[antonis]

https://www.aaroncake.net/circuits/fuzz.asp

[Rob Strand]

Too open ended.  You at least need the resistor values.

Maybe trace the circuit, add the part values you know.  A skeleton schematic will help narrow things down.
How the drive pot is wired also helps.

The diodes look like 1N914's to me.

It could be: (these are output clippers as opposed to antonis' feedback clippers)
- the distortion/fuzz section from the Morley BFW fuzz wah.
- there was a Schaller fuzz circuit from the late 70's similar to the Morley.
- MXR distortion +/DOD Overdrive
- Is that a transistor on the PCB?
  Maybe a Crowthers Hotcake?  There's a few versions.  Not sure off hand if one could be converted to LM741.

[Transistor-Transistor]

Too open ended.  You at least need the resistor values.

Maybe trace the circuit, add the part values you know.  A skeleton schematic will help narrow things down.
How the drive pot is wire also helps.

The diodes look like 1N914's to me.

It could be: (these are output clippers as opposed to antonis' feedback clippers)
- the distortion/fuzz section from the Morley BFW fuzz wah.
- there was a Schaller fuzz circuit from the late 70's similar to the Morley.
- MXR distortion +/DOD Overdrive
- Is that a transistor on the PCB?
  Maybe a Crowthers Hotcake?  There's a few versions.  Not sure off hand if one could be converted to LM741.

I'm working on a trace as we speak!
And yes that is a transistor on the board. I'm pretty sure it's just a buffer.

[Mark Hammer]

I'm guessing it's a Distortion+ if the diodes are germanium, or a DOD 250 if they are silicon.  From the picture, it looks like the output from pin 6 goes to the diodes, and the diode pair are connected to ground (white wire going to pin 4 of the IC), which would likely make it one of those two.

[Transistor-Transistor]

I'm guessing it's a Distortion+ if the diodes are germanium, or a DOD 250 if they are silicon.  From the picture, it looks like the output from pin 6 goes to the diodes, and the diode pair are connected to ground (white wire going to pin 4 of the IC), which would likely make it one of those two.

And I would agree with that, the only problem is that it sounds nothing like a distortion plus

Looking at the bottom picture makes it look like its actually NOT connected to ground, but actually the adjacent capacitor.

[Rob Strand]

Doesn't look like a distortion+ to me.  I think antonis got it with the feedback diodes but I haven't confirmed it's an inverting topology or not,

Pretty much something like the top part of this,
https://www.next.gr/uploads/12/Fuzzbox-Using-LM7411.gif
[This variant from Elektor magazine, 1977,
https://www.freestompboxes.org/viewtopic.php?t=32015]

No doubt with some small differences with the biasing.  Perhaps the opamp and BJT are biased from the same Vcc/2 supply.