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Anti-theft engine malfunction simulator

Anti-theft engine malfunction simulator

Car thieves are extremely inventive in finding and damaging anti-theft devices. But what if the engine periodically starts and stalls? If the car is equipped with equipment that simulates a malfunction of the engine, the potential thief will most likely not suspect the effect of 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   With the circuit closes again, allowing the thief to resume starting the engine. The cycle repeats, and after another 12   the engine stalls and does not start. By this time, the kidnapper may have moved a short distance from the parking lot.

The kidnapper can move 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 malfunction of the engine.

In the anti-theft device circuit shown in Fig.   1, IC timers 555 and K / MOS ICs consuming low current are used. When leaving the car, the driver activates the device with a disguised Si switch. Non-smoking drivers can disguise the Si switch in the lighter, the wire of which is disconnected from the battery and connected to the circuit at point A. For additional protection, the ignition switch can be connected in series with the Si switch.

After the circuit is set to working state by the Si switch, when the ignition is switched on, trigger 1 is assembled, assembled on two NAND gate, as a result, 0.5 Hz pulses from the output of the 555 timer go to the shift register CD 4015. The CD 4015 IC contains two four-bit register, which in this case are connected in series. After 12   with (six pulses) the NAND valves open the Q2 transistor, which opens the normally closed relay contacts and thereby shuts down the engine. After two more timer pulses arrive in the shift register, the NAND gate closes transistor Q2, allowing the motor to restart.

The cycle resumes, 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, who opens the Si switch. Timing diagrams are shown in detail in Fig. 2.

The start-stop periods of the anti-theft scheme are 12 and 4, respectively   from. After the engine stalls a third time, it cannot be started until the driver opens the Si switch, which is masked in the passenger compartment.

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

By connecting the terminals 5 and 12 of the shift register to an additional two-input NAND gate, you can receive an alarm through 60   from. The valve can control a relay, including an audible signal, headlights or a siren, if it is necessary to draw attention to the stolen car.

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