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Discussion in 'Electronic Basics' started by Jose Hernandez, Aug 11, 2003.

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  1. I want to install a flashing led (fake alarm) in my car but Instead of of
    connecting the led to a 1.5v battery I want to connect it directly to the
    car battery (12v) and have it turn OFF when the ignition is ON.

    Ignition Led
    Off On
    On Off

    What relay should I use?

    Thank You

  2. I wanted to do this too but I never really thought about how to do it. Also
    as a good way to protect your car is you could hook up a hidden switch to
    the starter on your car. if the switch is off it will never start. That's
    the poor mans car alarm.

  3. Why not just let it flash all the time? It's not like some potential thief
    is going to be watching it while you drive!


    Chip Shults
    My robotics, space and CGI web page -
  4. Bob

    Bob Guest

    Doh! Make that the normally closed contact.
  5. Bill Bowden

    Bill Bowden Guest

    You don't need a relay. Use a resistor from the LED to
    ground and put the led at +12. Then use a diode from
    the junction of the resistor/led to the ignition

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