Car anti-theft alarm circuit (1)

With the improvement of people's living standards, there are more and more private cars, and the problem of anti-theft has become more prominent. This inverter circuit is simple and reliable. It only costs a few yuan
to make the anti-theft alarm sound and cut off the lights when the car door is pried open. and oil circuit, preventing the car from starting.
    (1) Analysis of circuit working principle The circuit composition is shown in Figure 13-33.
555 time base integrated circuit as a delay oscillator. The function of the delay is to delay the alarm for 30 to 60 seconds after it is triggered, so that the owner has time to turn off the alarm
when the owner opens the door .     When the owner leaves the car and the car door is pried open by the car thief, the contact switch SB is closed, the relay Kl is energized and operates, the normally open contacts Kl-l and Kl-2 are closed , and the Kl-l contact is closed. The relay is self-locking, and the Kl-2 contact is closed so that the main circuit is powered on and starts working. When the voltage at point A rises to greater than or equal to 213Uce, the ③ pin of the output terminal of the 555 time base detection circuit outputs low level, the relay K2 acts, and the normally open contacts K2-1 and K2-2 close, causing the car speaker to beep continuously. An alarm sounds; at the same time, using the contacts of relay K2, the car lights and oil system can also be turned off and the car cannot be started .