ANSWERING_MACHINE_BEEPER

Published:2009/7/10 22:51:00 Author:May | From:SeekIC

When the light on the answering machine blinks, the resistance of photoresistor R1 charges, triggers the timer (U1), and generates 0.2-s pulse that activates BZ1. R1 is optically coupled to the LED on the answering machine and is properly light shielded.



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