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Car alarm that goes off when in a certain distance

Discussion in 'Security Alarms' started by [email protected], Feb 25, 2006.

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  1. Guest

    Hope someone can help with this.
    I would like to be able to set up a alarm on a car. It would only go
    off if the car got in certain distance of some point, say 100 feet.

    In other words if the car drove up to where I work my alarm would
    sound that the car is nearby.

    I looked a bit for proximity alarms and really couldn't find much what
    I was looking for. Any websites, adivce you could provide would help.
    Thank you
  2. mikey

    mikey Guest

    You could do something with a timer on a transmitter / receiver set up but
    it would be awkward. Garage door opener stuff falls in to that reception
    range I suppose but it's RF, not very precise.

    What about those dog fences? Can you bury a line?

    If you just want to detect a vehicle driving up, that's easy. I guess I
    should have asked that first.
    Something like this maybe?
    Bass would have jumped in by now but he gets uneasy at any mention of

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  3. Frank Olson

    Frank Olson Guest

    That's easy if you have an Ademco or DSC wireless system that
    annunciates "trouble" for a missing transmitter. You'd have to program
    a transmitter into your system, set up a relay correlation to either
    turn on a light or start a local buzzer when it's actually "present" in
    the system, and place the transmitter on the car you wanted to monitor.
    If it's within 200 feet of the receiver, the light/buzzer would turn
    "on". If it's out of range (or the battery's dead), the light/buzzer
    would be "off". The down side is that your system would also display
    "trouble" for the missing transmitter, but I think if you set it up on a
    different partition you could get around that.

    Frank Olson
  4. Frank Olson

    Frank Olson Guest

  5. mikey

    mikey Guest

    Not that easy. You've got the concept but it's not that fast, Frank. It
    depends on the window.
    My guess is the systems you mention are probably at least an hour, the car
    come and gone by then :)

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  6. Frank Olson

    Frank Olson Guest

    Yeah... You'd need something that transmitted continuously which would
    mean you'ld have to either hard wire the sucker to the vehicle's
    electrical system (can a 9 volt transmitter work on 14 volts?? I don't
    think so), or trip some sort of relay... easy enough to do if wire it
    to the ignition. Turning the engine off would energize the relay and
    open the contacts to the transmitter (it would transmit the open)
    instantly and accomplish two things... It would "log" back on to the
    security system and show an open zone. Starting the car would have the
    effect of "closing" the zone. The problem I see is that it sounds like
    the OP won't have that kind of access to the vehicle. A more
    clandestine approach is required. Like one of those card transmitters
    from HID. The reader for that guy's expensive though... and you'd need
    a head end unit to power it as well...
  7. Frank Olson

    Frank Olson Guest

    Excellent solution, Karl. I didn't realize they still sold mercury
    switches (what with the environmental concerns and all). I suppose any
    good movement detection switch would work (and automotive types would be
    weather-proof too). While I'm thinking about this we should also warn
    the OP that you can't guarantee the range on the transmitter will always
    be optimal. I'm not sure what to suggest about that as I've often found
    the position of the transmitter can affect the signal strength/range.
  8. Karl Magnus

    Karl Magnus Guest

    I have done this. I used a ITI transmitter (long life) and a Mercury
    switch attached to the input terminals. Dip the transmitter (once
    programmed in to your system) in that stuff they sell to coat your tool
    handles for protection. Then mount it on the "ledge" underneath the
    front t bumper or somewhere else. As a call pulls up and slows
    down/parks, the mercury will shift back and forth causing the
    transmitter to transmit. On the ITI stuff, you can put it in group 25
    (older panels) and it should be "non-supervised". This will cause the
    alarm to chime anytime the car pulls up withing range.

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