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This pedal works. I've biased the transistors correctly. Q1's Vc is 1.2v and Q2's Vc is 5v. I've checked all wiring, grounds etc... everything seems FINE. However when the fuzz knob is turned up to 8-10 the pedal has a high pitched squeal. The squeal goes away with the guitar volume turned all the way down. The signal still passes and sounds good when the squeal is happening and the squeal almost goes away when a big chord is struck. My belief is that the transistors are damaged but still functional. I don't have any of the BC108's in stock so I thought I'd post for insight before ordering them. Has anyone dealt with this specific issue?
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Ok so i couldn't figure out could have caused this unless it's bad design and hi frequency oscillation is an issue. So i did my own bandaid fix and it worked.
I added a .01uf snubbing cab across the bias and plate resistor - from Q2 collector to the 9v supply. Took care of the squeal. I also found the pedal to be really dark tone wise when the fuzz wasn't cranked so I added a 1uf cap from Q2 emitter to ground. Thought someone else may find this issue. -
I once had in a boutique fuzz pedal that howled and squealed like a banshee on many available settings. I fiddled with it for a while before doing some googling and discovering that this was all designed in, the manufacturer feeling that the best sounds were to be found on the edge of oscillation. Looking again at the circuit I saw the feedback loops that were producing the howls. So maybe it's like that kind of philosophy. Can't remember what the damn thing was called, sorry!Comment
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