DAM Meathead: Oscillation coming from BC108 transistor

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crossashi
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Joined: 18 May 2021, 00:37

Post by crossashi »

Hey all, saw someone having a similar issue with a tubescreamer the other day so I tried a different power supply like suggested to them, but no luck.

The video was taken yesterday, but today I took the circuit out of the 3pdt switch with an audio probe and now I can hear the full effect when playing, when I stop playing thats when the feedback/oscillation returns. When I was wired through the switch, I still got oscillation even when bypassed if I turned the volume knob up and it would change pitch. I traced the feedback sound starts when I touch the collector of the second transistor, and the 4k7 resistor touching it.

Any thoughts on what it could be? When I remove the second transistor from the circuit, the oscillation stops.

Thanks so much for any help.

video:
circuit: https://preview.redd.it/c1vzf5x8wjz61.j ... ca54d36a3b
Meathead Layout: https://preview.redd.it/b9un15x8wjz61.j ... eb2af592bb

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