The kidnappers cars are extremely resourceful in finding fault and anti-theft devices. What if the engine runs periodically and deaf? If the car is equipped with equipment to simulate an engine failure, a potential thief is not likely to suspect the protective device and will seek a new victim.
The new device provides normal start the engine, and after 12 breaks the circuit ignition coil, causing the engine stalls. 4 with the circuit closes again, allowing the thief to resume running of the engine. The cycle is repeated, and after another 12 with the engine stops and will not start. By this time the thief may drive off a short distance from the Parking lot.
The thief can pull away in a vehicle equipped with this scheme, however, he would soon abandon their intentions after repeated OST installation of the engine. IC timer periodically disconnects the voltage from the ignition coil, simulating an engine failure.
In the circuit of the protective device shown in Fig. 1, uses a 555 timer IC and/MOS IC, consuming low current. Leaving the car, the driver actuates the device disguised switch Si. Non-drivers may well over- masking of switch Si in the lighter cable is disconnected from the battery and connects to the circuit at point A. For additional protection can the ignition switch be connected in series with switch Si.
Once the scheme is established in the operating state of the switch Si, when the ignition trigger fires 1 assembled on two gates, as a result, the pulses 0.5 Hz from the output of the 555 timer receive shift register CD 4015. CD 4015 contains two four-digit register that this case connected in series. Later, with 12 (six pulses) gates open transistor Q2, which opens normally closed relay contacts and thereby suppresses the engine. Once in the shift register go two pulse timer valves NOT AND closes the transistor Q2, allowing the restart of the engine.
The cycle starts again, but when the ignition is switched on for the third time, the trigger is activated 2 and the start of the engine is locked until the driver comes back, which trips the switch Si. Timing diagrams shown in detail in Fig. 2.
Start-stop periods of the protective circuit are respectively 12 and 4. After the engine will stall for the third time, he could not be started until the driver opens the switch Si, disguised in the car.
To make the device different from the protective agent, it can be assembled on a small plate and place in the building, reminiscent of a device for monitoring of environmental pollution.
Connecting the conclusions of 5 and 12 of the shift register to an additional two-input gate are NOT-AND, you can get an alarm after 60 C. the Valve can control the relays switching audio signals, lights or siren, if you want to draw attention to kidnap car.
Analogues of chips:
555 - CREW
CD4011 - LA
CD4015 - IR
Publication: N. Bolshakov, rf.atnn.ru