SINGLE_OPAMP_TRANSISTOR_TESTER

Published:2009/7/11 1:54:00 Author:May | From:SeekIC

Meter scale is calibrated to read transistor gain directly for NPN devices. Addition of switch for reversing supply and meter polarities permits testing PNP devices as well. When reference voltage of 741 opamp is 5.3 V, circuit passes sufficient base current to make collector current 1 mA. Gain of transistor is then 1 mA divided by base current in microamperes; thus, 50-μA point on meter scale is marked for gain of 20 (1,000 divided by 50). Gain is 400 at 2.5 μA.-A. Rigby, Direet-Reading Transistor Tester, Wireless World, Aug. 1976, p 52.



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