Use NE555 to make a two-button touch light switch (1)

The circuit of the double-button touch light switch made with NE555 is shown in Figure 3-2. The circuit consists of touch electrodes, time base integrated circuits and bidirectional thyristor circuits.     The 220V alternating current is a simple capacitor step-down half-wave rectification and voltage stabilizing circuit composed of Cl, C2, VDI, and VD2 . After power on, a DC voltage of about 12V can be obtained at both ends of C2 for the time base circuit . When you need to turn on the light, just touch the "open" electrode piece M1 with your hand. The clutter signal induced by the human body is injected into the trigger terminal 2 of the time base circuit A, setting the time base circuit, and the output terminal 3 outputs a high level. Therefore, the thyristor VS can obtain a positive trigger current and turn on, and the lamp H emits light when energized. At this time, the LED also emits light to indicate the working status of the switch . When you need to turn off the light, just touch the "off" electrode piece M2 with your hand. The clutter signal induced by the human body is injected into the threshold terminal 6 of the time base circuit, the time base circuit A is reset immediately, and the output terminal 3 outputs low level. vs loses the trigger current. When the alternating current crosses zero, it turns off, the lamp H goes out, and the LED also goes out.