Simple homemade anti-theft circuit

This article describes a simple home security watchdog circuit (see the figure below). The time base circuit ne555 and r1, cl form a monostable flip-flop (1. The monostable flip-flop has only one steady state, one temporary steady state. 2. Under the action of an applied pulse, the monostable flip-flop can be stabilized from one The state is flipped to a temporary steady state. 3. Due to the action of the RC delay link in the circuit, the transient state remains back to the original steady state for a period of time, and the time of the transient steady state maintenance depends on the parameter value of the RC. Usually, c1 is discharged, the third pin of ne555 outputs low level, and the dog bark integrated circuit kd5608 does not work. m is a touch sheet and can be replaced by a lock body of the door lock. When an uninvited guest touches the door lock, the stray voltage induced by the human body acts on the second leg of the ne555, the monostable circuit is triggered to flip, the ne555 outputs a high level from the third pin, and the shit sound integrated circuit kd5608 is electrically operated. The dog's beep audio signal is output to the third pin of the audio power amplifier lm386, and the lm386 amplifies it to push the speaker to make a loud dog bark, so that the uninvited guest retreats. Thereafter, the power supply is charged to c1 via rl. When the voltage on c1 is charged to more than two-thirds of the power supply voltage, the monoflop flips again, the third pin of icl outputs a low level, and the shit sound integrated circuit kd5608 loses power. The speaker stops sounding. If the dog bark is too noisy when the family is unlocked during the day, you can press k at night to make the circuit only have night-time anti-theft effect.