555 kitchen ventilator self controlled switch circuit

Published:2011/6/3 8:19:00 Author:nelly | Keyword: kitchen ventilator, self controlled switch | From:SeekIC

As shown in the figure 12-29, this switch is self-control, when the north wind blows, the switch can automatically turns on/off intermittently, the harmful gas will be discharged to outdoor, it avoids the gas filling into bedroom. If K1 is closed due to the wind, IC1, IC2 are set, the output terminal is high level, VT1 turns on, J pulls in, suction fan runs. At the same time, C3 is charged by RP1, when it is charged to 2/3 VDD of the threshold value level, IC2 is reset, J is discharged, the ventilator stops to running. If the wind power decreases, switch K1 cuts off, then IC1 automatically resets by td1. If the wind power does not decrease, K1 is still closed, then two monostable circuit trigger and set again, ventilator starts again. In other words, the on/off time of K1 is decided by the outside wind direction and the wind power.



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