Double-watch timer circuit (1)

Published:2011/5/17 21:40:00 Author:TaoXi | Keyword: Double-watch, timer circuit | From:SeekIC

Related components PDF download: 9013 The circuit is as shown in the figure. This circuit uses two electronic wall watch with the alarm function, the signals is output from the both ends of piezoelectric ceramics. When the wall watch alarms, the signal gets to BG base port through C1 (or C2), and this signal is amplified to trigger the monostable circuit which is composed of the D flip-flop, Q1 outputs the high-level voltage and triggers the bistable circuit which is composed of the D flip-flop, Q2 outputs the high-level voltage and triggers the SCR to turn on; Meanwhile the LED lights, the Instruction timer is working. The monostable circuit's Q1 outputs the high-level voltage to charge C4 through R3, after a certain time, R1 has the high-level voltage to make Q1 to restore the low level. When the second watch alarm, the monostable circuit outputs a positive pulse to make the bistable circuit to output the low level voltage, so the LED turns off, the electrical equipments are out of electricity.



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