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door alarm kit

Discussion in 'Electronic Basics' started by diesel, Jan 22, 2006.

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  1. diesel

    diesel Guest


    you'll have to forgive my ignorance here but it has been a long time since i
    did my gcse in electronics nearly 20 years in fact so i've forgoten alot of
    it, but i have a question.

    i've had in my work place a large number of computers inside of wooden
    cages, unfortunatly these boxes are poorly constructed and it has become
    apparent that with some shaking of the door the locks pop out of their
    sockets. this has lead to a few people trying to steal the pc's.

    what i'd like to do is make a key armed alarm set-up with a led to show its
    armed, and a microswitch to put on the door to set it off when the doors

    like i said it has been a very long time since i did this last, and although
    i can still do the basics like solder, i really havn't cant remember much on
    the design.

    can anyone advise what i should get and how to construct it, i would prefer
    to remeber and construct it myself but unfortunatly i have to get this
    fitted sooner rather than later.

    many thanks in advance

  2. Dan Hollands

    Dan Hollands Guest

    why not just get some us the devices used for home alarm systems that
    monitor doors or windows - a lot easier and possibly even easier than trying
    to make your own. Losts on the the internet

    Dan Hollands
    1120 S Creek Dr
    Webster NY 14580
  3. diesel

    diesel Guest

    yeah i've looked at them but as these cages also contain money in them i'd
    prefer to have something that needs to be disarmed. rather than have the
    batteries ripped out. most of the systems i've seen like that could be
    disarmed fairly quickly if you know what your doing.

    also and this is the bigger aspect, the cost, we have 24 of these cases and
    we'd like to keep the cost down.

    also profile, with the system i'd like to install i'd like only the key
    switch and led to be seen, these cases have grills and lights inside so
    cables can be tacked to the edges and be hidden where as the units your
    refering to would be on display.

  4. Rich Webb

    Rich Webb Guest

    o arm/enable keyswitch
    '\ (A)
    o \
    | LED ___
    | |
    | |
    | ===
    | GND
    | |
    | |
    | '----. |
    | | | |
    | | | |
    '_ | o o
    ) | '\ '\
    ) | \ \
    ._) | o \ o \
    | | | |
    | | | |
    o-----' | |
    | | |
    | | |
    | o (B) | ,---. alarm
    |=|> | | X | device
    | o | '---'
    | | |
    | | |
    | | |
    === === ===
    (created by AACircuit v1.28 beta 10/06/04

    A double pole, single throw relay and a switch or two. Close master
    keyswitch (A) to arm the system. If switch (B) shuts, the relay
    energizes, shutting the two contact pairs. One pair of contacts sets off
    the alarm and the other acts as a sustaining path to ground so that the
    alarm continues even after switch (B) is open.

    (B) would be a "normally closed" microswitch that's held open when the
    door is shut against it. Open the door, switch closes, alarm goes off.
  5. Deefoo

    Deefoo Guest

    Why don't you fix the doors?

  6. diesel

    diesel Guest

    long story, awaiting joiners to return in about 2 weeks

    tbh i'd like an alarm on these units even after the doors are fixed.
  7. Rich Grise

    Rich Grise Guest

    You didn't say that. If you're trying to protect cash, you need something
    much more secure than a poorly constructed wooden box that people can open
    by just jostling it.

    Either get proper boxes, or station a 24 hr. armed guard.

    In other words, electronics won't solve your fundamental problem for you.

    Good Luck!
  8. Rich Grise

    Rich Grise Guest

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