The light control switch circuit of LDR

Published:2011/6/28 7:53:00 Author:qqtang | Keyword: light control switch, LDR | From:SeekIC

The power switch can be made of power MOS FET and the sensitive element can be the LDR. The light is shed on the LDR, it is in low resistance and there is a signal on the grid of the sound effect transistor, the source-drain is conducting, so the state of the relay is changed by K, which generates sounds and fulfills the control function. If the LDR is fixed at the low LEV sector, there won't be light on the LDR when it's dark outside, so the resistance of the LDR is high and the grid of the VMOS pipe is high, which makes the lamp L light.



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