Use BH-SK-1 to make non-contact infrared light switch

The non-contact infrared light switch circuit made with BH-SK-I is shown in Figure 3-42. It is mainly composed of sound- controlled integrated circuits,
infrared light-emitting tubes and receiving tubes, thyristor switch circuits and power circuits.
    The main circuit of the switch is composed of thyristor vs and diodes VD4--VD7. When vs is turned on, the light H lights up, and
when vs is turned off, the light goes out. The control loop is composed of a voice-activated integrated circuit, an infrared light-emitting and receiving tube, and other parts. The power supply of the control loop
is supplied by transformer T step-down, VD2, VD3 full-wave rectification and c] filtering. Both ends of cl can output a DC
voltage of about 8V. The infrared light-emitting tube LED lights up and radiates infrared light through the resistor Rl. R2, VD1 and C3 form a simple
voltage stabilizing circuit, which outputs a stable 6V DC voltage to supply power to the voice control integrated block A.
    The VT in the picture is a photosensitive transistor for infrared reception. Due to the arrangement, the infrared light emitted by the LED
cannot hit the VT. Therefore, the voice control integrated circuit is usually in a certain stable state. When this state is set, the output of pin 12 is low. Level
, vs off, light H does not light up. If your finger shakes in front of the switch panel, due to the reflection of the finger,
the infrared light emitted by the LED will illuminate the VT, making the VT equivalent resistance smaller, that is, the l pin of the input terminal of the integrated block will obtain a low-level
trigger signal, and the internal The bistable circuit flips, and pin 12 changes from the original low level to the high level, vs turns on, and the lamp H lights up.
If you shake it again in front of the switch panel, pin 1 of the integrated block will get another trigger signal, the internal bistable circuit will flip one
time, pin 12 will change from high level to low level , vs will turn off, and the light H will go out.