Light control switch circuit in incandescent lamp

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Under normal conditions, the alternating current forms a loop through a voltage divider circuit composed of an incandescent lamp, a VD4 to VD7 rectifier bridge, a resistor R9, and a voltage regulator circuit composed of VD3 and C4. The loop current is less than 0.9 mA, the power consumption is less than 0.2 W, and the illumination lamp is not lit. When the acoustic sensor receives the acoustic wave, the acoustic signal is converted into an electrical signal, amplified by two stages of IC1a and IC1b, and then the interference signal generated by the low-frequency vibration is removed by the coupling capacitor C1. When the ambient light is strong, the signal is bypassed by the photodiode VD1 and is not output to the latter stage; when the ambient light is weak, the VD1 is open, and the acoustic signal outputted by the front stage is amplified by IC1c and 1C1d, and VD2, C2, and R4 are composed. The rectification and filtering circuit rectifies the audio signal outputted by IC1d (directly charged to C2 via VD2) to a DC signal, and C2 and R4 have a delay effect, and the delay time is RC=22s. When the acoustic signal output by IC1d is a relatively short interfering signal, the transition time of the C2 output terminal from low to high is shorter than the transition time of the delay loop composed of R5 and C3. At this time, the output of C2 is short. The signal can not affect the C3 output level change, the interference signal is shielded; when the sound wave signal is normal, the level signal of the C2 output is delayed by the SCR via R5, C3, IC1f, R8, and the incandescent lamp is lit. Light control switch circuit in incandescent lamp: