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Thread: Ute box alarm

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    Default Ute box alarm

    Bought 3# Jaycar security plunger switches to put on the doors of my ute to connect an alarm. Checked the continuity of the switches and was surprised to find that when they are closed they are active, when open (extended) they are off
    My question is how do i get the alarm to sound when the power is off? Is there a relay or similar that will activate the alarm
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    Are you talking about the white coloured siren tamper switch. Post a pic of the type you have.

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    Alarms usually have normally open and normally closed connections, so either type of switch contact configurations can be used.

    If the alarm power is off, nothing will work, but I assume you mean just the sensor/switch, not the actual power itself.

    Yes, you could use a relay with double throw contacts in conjunction with the switch, making the circuit closed when the switch is released.

    What alarm are you using... does it have both NC and NO circuits?

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    Alarm switches are normally closed. That way the simple alarm can tell if the cable to them is cut.
    Once you move up a level, they use End Of Line Resistors so the alarm knows if the cable is cut or shorted.

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    Quote Originally Posted by allover View Post
    Bought 3# Jaycar security plunger switches to put on the doors of my ute to connect an alarm. Checked the continuity of the switches and was surprised to find that when they are closed they are active, when open (extended) they are off
    Quote Originally Posted by allover View Post
    My question is how do i get the alarm to sound when the power is off? Is there a relay or similar that will activate the alarm
    You did not specify what alarm you are using.

    If you just wanted to power on a simple siren with the switches without using any alarm hardware you could do this:
    You wire all the switches in series in a ring.
    The first switch is connected with one pole to chassis (GND) and the other connector with a single wire to the next switch. Then just wire in series from switch to switch(no GND) and the last wire goes to the coil of a 12V double throw relay. The other connection of the coil goes to permanent +12V but through a low rated fuse of course, never directly to the battery
    You connect your siren using the normally closed contact(NC) of the relay and in series to a hidden rocker switch switch to disable the alarm.
    Last edited by Uncle Fester; 08-01-20 at 11:26 AM.
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    bss904, yep see attached


    Guys, thanks for the replies, have only obtained the 3# switches at this point, already have a fuses and power in the tub, thought it only a matter of connecting to switches and a siren (with hidden cut off switch)
    Appears i have to purchase a double throw relay which i will get tomorrow
    There is a fine line between "Hobby" and "Madness"

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    Those tamper switches come in 2 flavours. NC pin in & NO pin in. The one your after is the NO Pin in and it should have a red dot on the back of the shell to identify it. I have just had a look through my stock and unfortunately I don't have any.

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    Just take them back to Jaycar and swap them for the correct ones.

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