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relay

Discussion in 'Electronic Basics' started by Danster, Apr 3, 2004.

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  1. Danster

    Danster Guest

    Hi- please can you help.
    Im after a relay which switches at 2vdc.
    I dont mind if its a minature or full size.
    Ill be switching 12v at about 1A.
    Any help much appreciated.
    Dan
     
  2. John Fields

    John Fields Guest

     
  3. CFoley1064

    CFoley1064 Guest

    Subject: relay

    The Digi-Key catalog is your friend. Look at the Aromat AGQ200S1H on page 1012
    of the current catalog. It's D-K p/n 255-1360-5-ND and is available for $3.80
    ea. in single quantities, and will switch 1 amp.

    It has a 1.5VDC coil, and has a maximum rated coil voltage of 2.25V, so you
    might want to consider using a series 1N4001 diode to drop coil voltage if
    you're going over 2.00V.

    Good luck
    Chris
     
  4. Danster

    Danster Guest

    Thanks for your help so far...
    The story goes...

    I race a vehicle which has a 'shift light' retro-fitted to the coil.
    At a certain rpm, an led is illuminated by a 2vdc input from a control
    circuit.
    -------------------------------------------------------------------------
    I want to use one of the currently unused the facia mounted warning
    lights, (which is illuminated by earthing a 12vdc (<1A) circuit).
    -------------------------------------------------------------------------
    Being a mechanical engineer, and not electrical, I thought I could use
    a
    relay fitted to the 2vdc input from the shift light and open the 12vdc
    circuit to earth, therefore turning on the warning light? I dont even
    know if this system would work, but to test it, I need to find a 2vdc
    relay (preferably in the uk?).
    Can somebody please tell me if im on the right track, and if not- why?
    Once again, thanks for any help.
    Dan
     
  5. Gareth

    Gareth Guest

    For electronic components in the UK try the following:

    www.maplin.co.uk

    http://rswww.com

    www.farnell.co.uk

    All three of the above sell relays so hopefully you can find a suitable one.

    Do you know which side of the LED is switched? I mean is one side of
    the LED permanently connected to ground and one side to a switched +2V
    or is it the ground side that is switched?

    Gareth.

    --
     
  6. CFoley1064

    CFoley1064 Guest

    Subject: Re: relay
    Hi, Dan. LEDs are current-controlled devices. It sounds like your LED is
    being driven by a signal with a series resistor which limits current to, say,
    20 mA or so.

    If that's the case, putting a relay coil in parallel with the LED won't do the
    trick -- neither one will go on. Even replacing the LED with a relay coil is
    no good, because the current-limiting resistor will prevent coil actuation.

    How about replacing the LED with an optocoupler IC like the 4N32? Pins 1 and 2
    are an LED, and pins 4, 5, and 6 are an optotransistor, which you can use to
    drive a real transistor to do the job. Maybe something like this will work
    (view in fixed font or M$ Notepad):

    Optocoupled Automotive Load
    VCC VCC
    | |
    | |
    | |
    | '------------o
    4N32 |
    1 | 1 Amp Load
    o-----. |5
    | |
    | ~ |/ .------------o
    V ~.--| |
    - | |> |
    | | | |
    | | |4 |
    o-----' | | ___ |/
    2 |6 o----|___|-----| TIP102
    o | 4.7K |>
    | |
    .-. |
    | | |
    | |4.7K |
    '-' |
    | |
    | |
    === ===
    GND GND

    If you want, you can also use a solid state relay, which basically has the
    above built in. It's simpler, and also allows a ground-referenced load.

    Good luck
    Chris
     
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