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relay information needed PLEASE!!!!

Discussion in 'Electronic Design' started by Vittorio, Apr 20, 2005.

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  1. Vittorio

    Vittorio Guest

    I've purchased a phone system that's capable of releasing typical
    magnetic locks remotely from any extension phone. An accessory called
    "external feature module" is responsible for deacivating a mag lock via
    a terminal block controlled by any phone. The circut is normally
    closed, when opened the power to the mag lock's rendered deactivated.
    My mag lock has to be deactivated by closing two leads. For some reason
    the manufacturer doesn't want the lock to be unpowered in order to gain
    egress. Here's my question. The telephone manufacturer tells me I need
    a "normally open" relay that serves a nomally open circut for my type
    of mag lock. If I select a 12 VDC (INPUT VOLTAGE) SPDT (CONTACT TYPE)
    10 AMPS (LOAD RATING @240 VAC), (POWER COMSUMPTION) 115 mA, 5 PIN RELAY
    - spade terminal relay. OR DO I NEED AN ENCLOSED POWER RELAY DPST-NO 25
    AMPS 12 VDC 158 mA (STANDARD WITH DC INPUT VOLTAGE) CAN YOU PEOPLE HELP
    ME MAKE THIS FLY?
     
  2. Ross Herbert

    Ross Herbert Guest


    Forgive me if I get this wrong. Are you talking about a door latch
    which is held closed by magnetic attraction such as
    http://www.tooldudes.com/securitron_magna32.html

    If so, then these latches must be permanently powered in order for the
    door to remain locked. Without knowing the details of your telephone
    system my guess is that it only provides a contact closure when you
    want to open a door latch remotely. This is exactly the opposite of
    what you want if you are using a Magnalatch.

    If the door latch interface on your telephone system has a form C
    changeover contact as the latch output then you could wire the
    Magnalatch via the normally closed contact instead of the normally
    open contact. I suspect that your system doesn't have a changeover
    contact but only has a single normally open contact instead. You can
    add a separate relay which does have a changeover contact, so that the
    door latch is wired via the normally made contact of this additional
    relay. When the phone system sends a signal to operate the relay
    momentarily the normally made contact will open and the Magnalatch
    will be released and the door can be opened. Of course, this relay has
    to be mounted somewhere close to the phone system and it must have a
    supply voltage suitable for the relay characteristics. It would be
    preferable if it could be mounted inside the phone system and utilise
    the dc supply which is provided.

    You would be aware that unless you have an uninteruptible power supply
    to power the Magnalatch then during power outages the door will be
    able to be opened at any time?
     
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