HFE & Leakage

Germanium Transistor hFE & Leakage Calculator

Using the R.G. Keen method, enter the two measured voltages to estimate transistor gain and leakage. Calculations use the constants in the original 9 V tester.

First voltage: leakage reading (V) Voltage measured during the leakage test. Second voltage: gain reading (V) Voltage measured during the hFE test.

Calculated results

Leakage current

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Leakage current (microamps)

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Estimated DC current gain (hFE)

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Enter both voltages to calculate leakage and hFE.

How the calculation works

These formulas preserve the calibration used in the supplied calculator:

Leakage (mA) = first voltage / 2.472

Leakage (microamps) = leakage (mA) x 1000

hFE = (second voltage - first voltage) x 100

The calculated leakage is not rounded before conversion to microamps. hFE is rounded to the nearest whole number rather than truncated.

The 2.472 divisor and gain multiplier of 100 come from the original code and are specific to that test arrangement. This calculator assumes a nominal 9 V supply. Temperature, test current and the actual supply voltage can affect germanium transistor measurements.