Simple circuit diagram of "empty city meter" anti-theft alarm

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

Photocoupler

The so-called empty city meter means that when the indoors are unoccupied or on duty, the lights can be automatically flashed after dark, and when someone breaks into the door, a delay alarm can be issued. The alarm consists of a monostable delay circuit (IC1), a light-controlled multivibrator (IC2), a step-down rectification power supply, and a thyristor trigger circuit.