Use BH-SK-1 to make a single-button touch light switch

The circuit of the single-button touch light switch made with BH-SK-I voice-activated integrated circuit is shown in Figure 3-40. The left
part of the dotted line in the figure is the ordinary lighting circuit, and the right part is the touch switch. As can be seen from the picture, it is the same as an ordinary mechanical switch, with only two external lead
wires, so it can easily replace an ordinary switch without changing the original indoor wiring.
    The main loop of the switch is composed of thyristor VS and diodes VD1 ~ VD4, and the voice-activated integrated circuit forms the control loop. R2,
VD5 and C2 form a simple voltage stabilizing circuit to provide 6V DC working voltage for the integrated block. Resistors R4 and R5 form a voltage divider
to provide a slightly higher voltage for the input terminal l pin of the integrated block. The bias voltage of 1/2 VDD puts the integrated block in a more sensitive working state.
Whether the thyristor VS is turned on or not depends on the switching state of the transistor VT. When VT is in the off state, vs can
obtain the touch current through the resistor R1 and turn on, the lamp H is lit; when VT is in the on state. The vs gate is shorted to ground by VT. vs
is in off state and the light is off. The sound control integrated circuit operates in a bistable state, and the level of pin 12 at its output
determines whether the light is on or off. If pin 12 outputs high level, VT is turned on, vs is turned off, and the light goes out.
When you need to turn on the light, just touch the electrode pad M with your finger. The clutter signal induced by the human body is added to the input
terminal pin 1 of the integrated block through resistor R6. After being processed by the internal circuit of the integrated block, the internal bistable flip-flop is flipped, and pin 12 outputs a low level, so
the triode VT is turned off. , vs is turned on, light the lamp H on the shell. If you touch the electrode piece M again, the bistable trigger
fork inside the integrated block flips once, pin 12 outputs high level, VT is on, vs is off, and the light H goes out. Therefore, by touching the electrode M with the hand,
the lights can be turned on and off. When vs is turned on and the light is on, the voltage across C2 will drop to about 3V.
Since BH-SK-I is a CMOS circuit with minimal power consumption, it can still maintain normal operation, so there is no need to worry about this.