Making touch thyristor zero-crossing switch circuit based on 555

Probe domestic switch needle KG-300K needle head diameter is 3.0mm normally open switch needle

555 and D1, D2, RP, C2 form a monostable timing circuit. When the human body touches the metal piece A, the sensing signal sets 555. When K is set to 1, the function is preset time td, then the control device Power off; if dialed to 2, its function is to preset time, the device power is turned on. Delay td = 1.1 RPC2. The length of the delay can be adjusted with RP.