Sound control power saving switch circuit

The power-saving switch introduced below is turned off during the day or when the light is bright, and the lights do not light up. At night or when the light is dark, the power-saving switch is in the ready working state. When someone passes near the switch, the sound of footsteps, voices, clapping, etc. can activate the power-saving switch and the light will turn on. After a delay of 40-50s,
the power-saving switch will turn on. The power-saving switch turns off automatically and the lights go out.     (1) Guilu Working Principle The sound-controlled power- saving switch circuit consists of 7 circuits: microphone BM, sound signal amplification, half-wave rectifier, light control, electronic switch, delay and AC switch. The circuit principle is shown in Figure 10-26 . The microphone and VT1, Ri~R, and Ci form a sound amplification circuit. In order to obtain higher sensitivity, the Lu value of VT1 should be greater than 100, and the microphone should be selected with high sensitivity. R3 should not be too small, otherwise the circuit is prone to intermittent oscillation. C2, VD1 and VD2, G form a rectifier circuit to convert the sound signal into a DC control voltage. Product, R5 and photoresistor RG form a light control circuit. When light shines on RG, its resistance becomes smaller and the DC control voltage attenuates greatly. VT2 cut off. VT2, VT3 r and MA, VD3 form an electronic switch. Normally, that is, when there is light, vr2 and VT3 are cut off, there is no voltage on C4, the unidirectional thyristor VTH is cut off, and the bulb HL does not light up. When VTH is cut off, the DC high voltage is stepped down by R9 and VD4 and then added to the upper end of C6 to charge G. When charged to 12V, VS breaks down. Make sure the voltage on G does not exceed 15v. ．