The simplest anti-theft device

A simple but effective anti-theft device with your own hands. Such a device can be made quite quickly and simply. Difficult and expensive parts will not be required, but despite this, the device can be very useful in protecting your favorite horse. At present, anti-theft devices have gone along the path of complication, and even space technologies are present in their manufacture, but despite this, the protection of the car is still relevant. Hijackers are also developing and applying the same modern technology.
Perhaps this simple device will be the means that will confuse the kidnapper, counting that everywhere there are "steep" anti-theft.
The scheme works like this: anti-theft enabled. The intruder opens the door, turns on the ignition, starts the engine and is happy that he has succeeded. But suddenly the engine stalls. He turns it on again, but after 5 to 15 seconds (depending on how you adjusted the anti-theft device), the engine stops again and there is a feeling that there is a problem with the fuel system.But he will not find a fault, since the time relay blocks the engine ignition system with a delay of the blocking time, and not the fuel one.
The proposed anti-theft device, in fact, is a relay with a delay time to turn on.

Here is his diagram


The simplest anti-theft device

Parts are used for this device.
The simplest anti-theft device

  • D1 chip - K176LA7 or its imported analogue CD4011.
  • VT1 transistor - KT315 with any letter or import 2SC634, 2SC633, BFP722, 2N2712, BFP720, BFP721, BFP719.
  • The transistor VT2 - KT815 or BD 135, BD 139, BD 137.
  • The capacitor C1 - 33 MKF 25 volts.
  • Capacitor C2 - 10 - 20 MkF 25 volts. This capacitor is the time master, which means that the amount of time delay until the relay is turned on depends on its capacity. With a 10 microfarad capacitor - time is about 7 seconds, and 20 microfarad - about 15 seconds, but it also depends on the resistor R1, which is also a component of the time of the driving chain - R1 - C2 and the time depends on its resistance too.
  • R1 is about 300 Kom, but I put a potentiometer at 680 Kom, in order to be able to demonstrate the change in the time delay before the relay Rel1 is switched on, depending on the amount of its resistance. In the finished device, when you have decided which time delay suits you, you can replace the potentiometer by a constant resistance equal to the potentiometer resistance.
  • R2 is 100 ohms.
  • S1 - any toggle switch, switch, which one you like.It will be safely hidden in the car.
  • A toggle switch is connected to terminal 1, and a toggle switch is connected to the wire that receives power after the ignition switch is turned on.
  • Terminal 2 is connected to the ignition interrupter wire. When the device is turned on, the contact of the anti-theft relay will close the breaker wire to ground and thereby muffle the engine.
  • Terminal 3 connects to ground.
  • Make the device better on the breadboard, so it will be easier and faster.

Device assembly


The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

We solder the wires to the toggle switch and the potentiometer and connect them to the circuit.
The simplest anti-theft device

The simplest anti-theft device

The simplest anti-theft device

The finished device is connected to a 12 volt battery.
The simplest anti-theft device

Anti-theft device works.
The simplest anti-theft device

The device board must be placed in the case and filled with sealant in order to avoid mechanical damage and short circuits.
Watch the video showing the dependence of the time delay before switching on the relay on the resistance of the potentiometer.

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