My 2 transistor overdrive/distortion pedal. I based part of it off some of the lower gain 1 transistor 'grit' pedals and added another transistor to the preamp section to add a bit
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Dunlop JDF2 Fuzz Face Distortion Pedal, Germanium PNP Transistor, Red
Very Simple and Cheap Guitar/Bass Distortion Pedal : 4 Steps - Instructables