The sound control duty alarm circuit

Published:2011/6/26 22:16:00 Author:Borg | Keyword: sound control, duty alarm | From:SeekIC

In the figure is the sound control duty alarm circuit. The alarm consists of the DC regulated power supply, timing switch circuit and sound control pulse generator. In the circuit, S is the microphone, which converts the step sound and other sounds into the electric signals, and the signals are added on the trigger terminal 2-pin of the 555 time-based circuit. 555, R6 and C2 compose a single steady trigger, the adjusting resistor R6 makes the voltage on 2-pin a little higher than 1/3VDD. The 3-pin of 555 outputs a low LEV. When there's something happening, BG2 is outputting a passive pulse of certain amplitude, which reverses 555.



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