A Darlington distortion/fuzz with clipping toggle, BMP tone control and tea philter.
It consists (in order of signal flow) of three MPSA13 electra distortion stages, a BMP tone control, an MPSA13 recovery stage, diode clipping, a tea philter and a volume control. The pointed dial toggles five clipping types: red LED, silicon diodes, germanium diodes, socketed mixed silicon/twin germanium and no clipping. The gain switch toggles between high and higher gain in the first stages.
The tea philter is a great effect in itself, giving a cocked wah type sound. It can also be controlled by an expression pedal. Using the 555 LDR EXP to modulate the filter yields harmonic tremolo-ish sounds.
Between the tone shaping, clipping, filter and gain options it is capable of a wide range of drive and fuzz sounds from straight forward overdrive through sounds-like-coming-from-the-neighbor muddyness to sizzling biting fuzz on the brink of self destruction.