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Calculate Big Muff Resistors

This calculator is used to determine resistor values for the basic shunt feedback transistor circuit to set the proper DC operating point.

Capacitors are not important to the calculations so they are not numbered. The Hfe and leakage of the transistors will be important to the calculations. (see below)

Try to adjust resistor values so that Vc is 4.5v to 5.0v for best operation.

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 enter 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 Big Muff Calculator
Rc (k ohms) Re (k ohms)
R1 (k ohms) R2 (k ohms)
Q1 hfe Q1 Vbe
Q1 leakage (ma) Voltage Supply
Vc (v) Vb (v) Vb (v)
ic (ma) ib (ma) ie (ma)
i1 (ma) i2 (ma) i (ma)

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


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