555 touch timer switch circuit

(1) Introduction to circuit principle Integrated circuit IC1 is a 555 timing circuit, which is connected to a monostable circuit here. Normally, since there is no induced voltage at the P end of the touch
chip , the capacitor cl is discharged through the ⑦ pin of 555, the @ pin output is low level, the relay K is released, and the light does not light up. When you need to turn on
the light, touch the metal piece P with your hand. The clutter signal voltage induced by the human body
is added from cz to the trigger end of 555, causing the output of 555
to change from low level to high level, relay K is closed, and the light is lit. At the same
time, the inner side of pin 7 of 555 is cut off, and the power supply charges c1 through R1
. This is the start of timing. ,
    when the voltage on the capacitor Cl rises to 2/3 of the power supply voltage.
555 pin ⑦ is turned on to discharge cl, causing the output of pin @
to change from high level back to low level, the relay is released, the light goes out, timing
    '?
Finish.
    (2) Competing device parameter selection. The selection of components
is shown in Figure 3-10. There are no special requirements.
    (3) The 555 trigger timing switch circuit is shown in Figure 3-10.