This is the circuit diagram of Octaver-Fuzz Guitar Effects Unit that easy to. Above schematic diagram was extracted from ETI-Canada, January 1980. The transistor Q1 is MPS6515, The diode DI and D2 are 1N4148. The IC is any low noise dual op-amp, shown on above scheme is the 4558. Switching could be improved with a full bypass mod.
The (Guitar Effects Unit) GEU is good sounding octave fuzz, with an optional mode of just fuzz. The fuzz is a fully rectified signal and is quite chewy. For some the Fuzz alone might not be loud enough, this can be fixed by increasing the value of the 820 ohm resistor and lowering the 39k one. Or one could just replace both with a normal volume potensiometer for a more standard approach. The “struzz” is the fuzz with an octave higher signal mixed in. Good for signal notes and leads.
