Light-operated switch circuit

Published:2012/8/19 22:12:00 Author:Ecco | Keyword: Light-operated switch | From:SeekIC

As shown in figure, under normal conditions, the AC voltage passes incandescent, VD4 ~ VD7 bridge rectifier, voltage divider circuit composed of resistor R9 and regulator circuit composed of VD3, C4 to form a loop, the loop current is less than 0.9 mA, power consumption is less than 0.2W, then lights are not bright. When sound sensitive components receive acoustic, acoustic signal is converted into electrical signal, then it passes IC1a, IC1b to make two-stage amplification, and the coupling capacitor C1 will remove the interference signal generated by the low-frequency vibration. When the ambient light is strong, the signal is bypassed by photosensitive diode VD1, and it won't be output for following stage; when the ambient light is weak, VD1 is open, pre- output acoustic signal is amplified by IC1c and 1C1d, VD2, C2, R4 form rectifier and filter circuit to rectify audio signal output by IC1d into a DC signal.



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