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Anti-theft engine fault simulator

Anti-theft engine fault simulator

Car thieves are extremely inventive in finding and damaging anti-theft devices. And what if the engine periodically starts and stalls? If the car is equipped with equipment that simulates an engine malfunction, the potential thief will most likely not suspect the anti-theft device and will search for a new victim.

The new device provides a normal engine start, and after 12   C opens the ignition coil circuit, causing the engine to stall. After 4   the circuit closes again, allowing the thief to restart the engine. The cycle is repeated, and after another 12   With the engine stalls and does not start. By this time, the abductor may have moved off a short distance from the parking lot.

The thief can start off in a car equipped with this scheme, but he will soon give up his intentions after repeatedly stopping the engine. The timer IC periodically disconnects the voltage from the ignition coil, simulating a faulty engine.

In the scheme of the anti-theft device shown in Fig.   1, is used IC timers 555 and K / MOS ICs that consume low current. Leaving the car, the driver activates the device with a masked Si switch. Non-smoking drivers may well mask the Si switch in a lighter, the wire of which is disconnected from the battery and connected to the circuit at point A. For additional protection, you can connect the ignition switch in series with the Si switch.

After the circuit is set to the operating state with the Si switch, when the ignition is switched on, trigger 1 is triggered, assembled on two NOT-AND valves, and as a result, 0.5 Hz pulses from the 555 timer output go to the CD 4015 shift register. register, which in this case are connected in series. 12 after   with (six pulses), the N-AND gates open the Q2 transistor, which opens the normally closed relay contacts and thereby turns off the motor. After two more pulses of the timer arrive in the shift register, the gates NOT AND close the Q2 transistor, allowing the motor to restart.

The cycle is resumed, but when the ignition is turned on for the third time, trigger 2 is turned on and the engine start is blocked until the driver returns and opens the switch Si . Timing diagrams are shown in detail in Fig. 2

Start-stop periods of the anti-theft scheme are 12 and 4, respectively.   with. After the engine stalls for the third time, it cannot be started until the driver opens the switch Si disguised inside the car.

To make a device unlike an anti-theft tool, it can be assembled on a small board and placed in a housing that resembles a device for monitoring environmental pollution.

By connecting pins 5 and 12 of the shift register to the additional two-input valve NOT AND, you can receive an alarm after 60   with. The valve can control the relay, including a horn, lights or a siren, if it is necessary to draw attention to the car being stolen.

Analogs of microcircuits: 555 - KR1006VI1 CD4011 - 561LA7 CD4015 - 561IR2.