TRANSISTOR_AND_DIODE_TESTER

Published:2009/7/11 3:56:00 Author:May | From:SeekIC

Four pairs of,AA penlight cells provide power for testing transistors and diodes quickly for opens and shorts. Circuit also distinguishes between PNP and NPN transistors and shows diode polarity. Leads of diode are inserted into base and collectoriacks (B and C), and switches are prqssed in succession. If LED 1 glows, diode is good and its anode lead is in collector jack. If LED 3 glows when S2 is pressed, anode of diode is in base jack. If both LEDs glow, diode is shorted. If neither LED glows, diode is open. With transistor in tester, unit is PNP if LED 1 and LED 2 glow. If LED 3 and LED 4 glow, unit is NPN. If one or no LEDs glow, transistor is open. If three or more LEDs glow, transistor has shorted junction. Any LEDs can be used.-F.M. Mims, Transistor Projects, Vol. 3, Radio Shack, Fort Worth, TX, 1975, p 87-93.



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