The ‘fuzz’ sound is derived by clipping the input waveform, thereby enriching the signal with odd harmonic which provide the hash sound. This circuit “Fuzz Effect Box for Guitarists” is a basic project produces a fuzz which gradually decays into a ‘clean signal’.
The circuit uses the standard op-amp 741 in non-inverting configuration. The gain of this amplifier is controlled by the feedback network comprising VR1, R2 and R3.
Input signal from the guitar passes to the op-amp through DC blocking capacitors C1. Resistor R1 sets the input impedance at 100 K, which suits most guitars. Resulting signals from the op-amp are reduced in amplitude by the potential divider action of R6 and R7 giving an attenuation factor of approximately four. Thus the maximum output signal via capacitor C3 available for inputting to an amplifier is about 150mV. This level is maintained during the period of clipping (fuzz) and then decays naturally to zero.
A footswitch may be used to bypass the signal whenever required. The whole circuit can be assembled on a general-purpose PCB. A red LED can be used to indicate that the “Fuzz Effect” is ‘ON’ by coupling it to the bypass switch suitably.
This unit is power by 8V PP3 battery.
Resistor (all ¼-watt, ± 5% Carbon)
R1 = 100 KΩ
R2 = 1.2 KΩ
R3 – R5 = 10 KΩ
R6 = 3.3 KΩ
R7 = 1.8 KΩ
VR1 = 100 KΩ LIN.
C1, C3 = 0.1 µF
C2 = 10 µF/16V
IC1 = LM741
D1, D2 = 1N4148
LED1 = RED LED