Sound remote control switch circuit

For the voice control circuit introduced in this section, during the day or when the light is bright, the voice control switch is turned off and the light does not light up. At night or when the light is dark, the voice
-activated switch is in preset working state. When someone passes near the switch, the sound of footsteps, voices, and clapping can activate the voice-activated switch, and the light will turn
on. After a delay of 40-50 seconds, the voice-activated switch will automatically turn off and the light will go out.
    (1) Working principle The voice-controlled switch circuit is composed of 7 circuit parts: microphone BM, sound signal amplifier, half-wave rectifier, light control, electronic switch, delay
and AC switch. The circuit principle is shown in Figure 18-26. Microphone and VT1, R. ~R3,C. Form a sound amplification
circuit. In order to obtain higher sensitivity, the value of VT1 should be greater than 100. Microphones are also selected with high sensitivity. Pu should not be too small, otherwise
the circuit is prone to intermittent oscillation. G, VD1, VD2, and C3 form a rectifier circuit to convert the sound signal into a DC control voltage . R4, Rs
and photosensitive resistor R(; form a light control circuit. When light shines on RG, its resistance becomes smaller, the DC control voltage attenuates greatly, and VT2 is cut off.
VT2, VT3, R, and VD3 form an electronic switch. Normally, that is, when there is light, VT2 and VT3 are cut off. There is no voltage on C4. The one-way thyristor
VTH is cut off and the bulb HL is not bright. When VFH is cut off, the DC high voltage is stepped down by R9 and VD4 and then added to the upper end of Cf to charge C6 , after
charging to 12V, VSI breaks down, ensuring that the voltage on C6 does not exceed 15V.
    When no light shines on RG, the resistance of RG is very large, and the attenuation of the DC control voltage is very small. VT2 and VT3 are turned on, VD3 is also turned on.
G and C5 start charging, and the voltage slowly rises. Wind, 0 and unidirectional thyristor VS form a delay and AC switch. C4 adds the DC trigger
voltage to the VTH control gate through Ra, VTH turns on, and the relay coil When K is powered, the normally open contact K of the relay in the EL branch is connected, and the bulb
EL lights up. The length of time the bulb lights up is determined by the parameters of C4 and Yan. According to the component values ​​​​given in the figure, the bulb After lighting for about 40 seconds,
\rrHa& stops and the light goes out. G is an anti-interference capacitor, which is used to slightly eliminate the light bulb jitter phenomenon i
    (2) Component selection VT1 and VT2 both use 9014 transistors, VT3 uses 9012 transistors, of which VT1 needs Choose J;B>100.
Use 100-8 unidirectional thyristor for VTH. Use 1N4148 diodes for VD1-VD3, 1N4001 diodes for VD4, and
1N4004 diodes for VD5~VD8. The microphone should be used with high sensitivity. Other components are as shown in the figure.