555 simple transistors tester circuit

Published:2011/4/26 1:08:00 Author:Ecco | Keyword: 555 , simple, transistors , tester | From:SeekIC

As shown in Figure 7-19, the test instrument is composed of the non-steady-state multivibrator composed of 555 and R1, R2, C1 and the driver of tested grades crystals. It can measure the quality of NPN transistor and estimate B value, the oscillator's oscillation frequency f = 1.44 / (R1 +2 R2) C1. Icon parameter oscillation frequency is about 850Hz. If you plug in the tube, no sound means bad tube; if the sound is small, it indicates that B is low, while loud, B is high.



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