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simple question (probably..)

Discussion in 'Electronic Basics' started by quintero, Oct 5, 2004.

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  1. quintero

    quintero Guest

    i have this door opener which has a 2 wires connected to it, basically
    if i connect the 2 wires together the door opens.
    now i want to connect these wires in some way to the com port in my
    computer, so i can control the door with some software. i know how to
    set RTS and DTR, but how do i complete the ciruit and connect the 2
    wires together?
  2. John Fields

    John Fields Guest

    Like this:

    | +------->TO DOOR WIRE 1
    +------+ |NO
    |K | O-> |
    [DIODE] [COIL]- - - -|COM
    | | O--->TO DOOR WIRE 2
    RTS>---[4K7]-+---B NPN
    |K E
    [DIODE] |
    | |
    SIGNAL GND>--+-----+

    Assert RTS momentarily when you want the door to open.
  3. Bill Bowden

    Bill Bowden Guest

    You can probably use a solid state relay. The relay will
    have a LED inside that controls a photo sensitive switch.
    They will usually work at 10-20 mA, but I'm not sure how
    much current you can get from the com port. Look around
    for a SS relay that operates on low current of just a few mA.

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