LIGHT_ACTIVATED_ALARM_WITH_LATCH

Published:2009/6/14 22:55:00 Author:May | From:SeekIC

In this circuit, light causes R5 to conduct forward-biasing Q1. R6 sets sensitivity. SCR1 is triggered from the emitter voltage on LQ1, sounding the alarm bell. When 51 is depressed, SCR1 un-latches. Be sure that a self-interrupting alarm (electromechanical buzzer or bell) is used.



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