Touch mode timing energy-saving lamp circuit based on 555 chip

Memory chip

The step-down rectifier circuit is composed of a transformer T, diodes VD1 to VD4, and a capacitor C1. The LED is a power indicator light and has a charging indication as a battery G.
As shown in Figure 18-32, the circuit consists of an AC step-down rectifier circuit, a monostable delay circuit, and a thyristor trigger circuit. Mainly used for stairs, offices and other occasions. After people leave, they will automatically turn off the lights after a few minutes.
555 RP, C5, C3, etc. constitute a touch type monostable delay circuit. Normally, the 2 feet are suspended, and the discharge tube inside the integrated chip connected to the 7-pin is saturated and turned on, the 555 is in the reset state, the 3 feet are at the low level, the SCR is cut off, and the bulb is not lit. When the human body touches the metal piece, the induction clutter is added to the trigger terminal 2, 555 is set, the output is high, the SCR triggers the conduction, and the bulb is illuminated. At this time, the discharge tube in the substrate is turned off, C5 is charged by the RP, and the circuit is in a transient state. When the voltage on C5 is charged above the trigger level 2/3VDD, 555 is reset and the output is low. The charging time of the capacitor, that is, the delay time after touch td=1.1RPC5, the delay of the illustrated parameter is up to about 7 minutes, which can be changed by adjusting the potentiometer RP.