Alarm circuit help

Discussion in 'The Projects Forum' started by Deranged, Feb 16, 2010.

  1. Deranged

    Thread Starter New Member

    Feb 16, 2010
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    Okay, I am in need of assistance in getting a fob system to work with my building alarm. What I have is a keyless entry fob on the outside and inside of the door. It is currently set up so that if the door is opened the alarm goes off, regardless if you swipe your fob or not. What I need to do is this:

    Swipe fob and it closes the alarm switch so it doesn't go off when the door is opened. But I need this alarm switch closed until the door is closed than the alarm would go off again if someone who doesn't have fob access opens the door. The door is not lockable as it has an emergency exit push bar.

    I hope I haven't confused anyone.

    Thanks in advance.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
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    Can you post up the alarm circuit as it exists?
     
  3. Deranged

    Thread Starter New Member

    Feb 16, 2010
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    I don't have the current circuit drawing for it, but it is just triggered by the reed switch opening when the door opens.
     
  4. gerty

    AAC Fanatic!

    Aug 30, 2007
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    I don't know what you have for alarm contacts, but it sounds like you need some timed contacts to shunt out (wired in parallel) your door switch .
    swiping the fob would activate the timed contacts to close, bypassing the door contacts allowing it to be opened without alarm. After the time expires the door would then be the only contacts in the loop.
     
  5. Deranged

    Thread Starter New Member

    Feb 16, 2010
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    That would be my preferred way, but the company I work for wants to be able to leave the door open for an undetermined amount of time and when the door closes it reactivates it.
     
  6. gerty

    AAC Fanatic!

    Aug 30, 2007
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    If that is the case, you will need latching alarm contacts, but the fob will have to be swiped again to re-arm the door.
    And of course you will not be protected while the door is bypassed. With a situation like this you'll need indicator lights/leds to determine the status, which may or may not be to the liking of the owners. Plus you'll be at the mercy of the person that bypassed it to remember to return it to the armed state. Since the door is to be propped open, maybe a second switch can be added to re-arm it when it closes.
    We're kinda shooting in the dark here without knowing what you have....
     
  7. Deranged

    Thread Starter New Member

    Feb 16, 2010
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    After closing it I want it rearmed. The fob system and the alarm system are both independent of each other. The only thing I need is to close the contacts for the reed switch on the alarm when the fob is swiped then once the door is closed the contacts are then no longer operated by the fob.
     
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