Hijack Alarm

Posted on Feb 5, 2014

The first circuit was designed for the situation where a hijacker forces the driver from the vehicle. If a door is opened while the ignition is switched on - the circuit will trip. After a few minutes delay - when the thief is at a safe distance - the alarm will sound and the engine will fail. Before fitting this or any other engine cut-out to you

Hijack Alarm
Click here to download the full size of the above Circuit.

r vehicle - carefully consider both the safety implications of its possible failure - and the legal consequences of installing a device that could cause an accident. If you decide to proceed - you will need to use the highest standards of materials and workmanship. You`re going to trip this alarm unintentionally. When you do - the LED will light and the Buzzer will give a short beep. The length of the beep is determined by C3. Its purpose is to alert you to the need to push the reset button. When you push the button - the LED will switch-off. Its purpose is to reassure you that the alarm has in fact reset. If the reset button is not pressed then - about 3 minutes later - both the Siren and the Buzzer will sound continuously. The length of the delay is set by R7 & C4. For extra effect - fit a second siren inside the vehicle. With enough noise going on - you may feel that it`s unnecessary to fit the engine cut-out. In which case - you can leave out D8, D9, R11, R12, R13, C6, Q3, Q4 & Ry2. Even if you missed the early warning provided by the Buzzer - there is still time to reset the alarm before Ry2 de-energizes - and the engine fails. This additional delay - currently about 1 minute - is set by C6 and R13. To reset the circuit you must - EITHER turn off the ignition - OR close all of the doors - before you press the reset button. While BOTH the ignition is on - AND a door remains open - the circuit will NOT reset. The reset...

Leave Comment

characters left:

Related Circuits

  • New Circuits



    Popular Circuits

    Simple Electric Field Detector
    Variable Voltage Regulator
    How LCD Display Interface Circuit works
    12V Powered 12V Lead Acid Battery Charger with Indicator
    Microphone Circuit Test Oscillator
    LEDs or Lamps Sequencers
    12v To 220v Inverter 180w By 2n3055
    FM CB radio receiver circuit design using TCA440
    Real-Time Energy Monitor with Arduino and LabVIEW
    Selfrunning Free Energy 5 KW Kapanadze 2
    Adaptive zero voltage switching electronic ballasts
    Length 1 minute delay relay pull transistor circuit diagram
    Digital Cameras -DV machine power supply circuit
    Easy Auto power battery charging circuit
    Asia ultrasonic remote control fan speed control circuit diagram