PHOTOTRANSISTOR_RELAY

Published:2009/7/6 6:07:00 Author:May | From:SeekIC

With phototransistor Q1 dark, R1 biases Q2 into conduction and miniature SPDT relay (Radio Shack 275-004) is energized. When light falls on Q1, Q2 is turned off and relay drops out. Battery drain is about 5 mA in darkness, dropping almost to 0 mA with light.-F. M. Mims, Transistor Projects, Vol. 3, Radio Shack, Fort Worth, TX, 1975, p 69-74.



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