High-current hfe tester

A conventional current gain tester is too unreliable for measuring and comparing the d.c. gain of power transistors because it fails to set the collector current at a value that reflects the actual working conditions in, say, the output stage of an audio power amplifier. The tester described here measures the large-signal gain, hFE,of n-p-n as weil as p-n-p transistors at a collector current of up to 10 A, yet does not require a bulky power supply.