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Calculate Fuzzface Resistors

This calculator is used to determine resistor values for the basic fuzz face circuit to set the desired DC operating point.

Capacitors are not important to the calculations so they are not numbered. R2 is equal to the sum of R2a and R2b. Example: If R2a=680 and R2b=8200 then R2 is 8880 ohms for use in the calculations.

The Hfe and leakage of the transistors will be important to the calculations.

The Vbe values are the voltage drop across the transistor junctions. Use 0.65 for all silicon transistors but the value can vary for germanium devices. A good estimate would be 0.3 for starters.

Leakage values are in milliamps so a 150 microamp leakage on a germanium transistor would be entered as 0.15 and not 150. Leakage for silicon transistors is always 0.

Also remember that resistor values are in kilohms, so a 33k collector resistor on Q1 is entered as 33 and not 33000.

AMZ Fuzzface Calculator
R1 R2
R3 R4
Q1 hfe Q1 Vbe
Q1 leakage (ma)
Q2 hfe Q2 Vbe
Q2 leakage (ma) Voltage Supply
Vc1 (v) Vc2 (v)
ic1 (ma) ic2 (ma)
ib1 (ma) ib2 (ma)
ie1 (ma) ie2 (ma)
i1 (ma) i3 (ma)
V4 (v) Ve2 (v)

If you have trouble getting the proper settings, click here for a sample screen of values.

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