The door control,light-dependent control switch circuit

Published:2011/6/27 23:45:00 Author:Fiona | Keyword: The door control, light-dependent control | From:SeekIC

When opens the door,the contact of the key switch SB is closed.The city power reduces voltage by the capacitor C1,rectifys by the diode VDl,indicator light LED is lit.At the same time,the city power reduces voltage by c2,then outputs 12v dc voltage by c3 after filtering. During the day,the resistance of the phototransistor VTl becomes smaller by the light, when it reaches a - threshold, vT2 conducts, the collector of vT2 is low, although thelight dependent resistor RG receives the light but it can not make VT3 conduct.The relay KM is no electricity,the contact KM-1, KM-2 are off,floodlight H is not bright.



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