555 simple practical earthquake alarm circuit

Published:2011/5/30 21:08:00 Author:TaoXi | Keyword: 555, simple, practical, earthquake, alarm circuit | From:SeekIC

The earthquake alarm circuit is composed of the shock vibration sensor, the monostable timing circuit and the voice alarm circuit.etc, as the figure 15-51 shows. This circuit has the function of sound & light alarm to the earthquake which is more than 4 class in the medium or short distance. The IC1 uses the time base circuit 555, the monostable trigger timing circuit is composed of the 555 and the R2，C1. In peace time, the pin-2 has the high electric potential to make the 555 in the reset state. If the earthquake happens, the hammer touches with the outer phase, pin-2's low electric potential makes the 555 in the set state,pin-3 outputs the high electric potential to supply the power to IC2 voice generating circuit. The monostable temporary stabilization time td=1.1R2C1.



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