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Thread: How do I wire a momentary switch correctly?

  1. #1
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    Angry How do I wire a momentary switch correctly?

    This seems like it should be simple, but for some reason it just isn't working.
    I purchased this momentary switch: http://store.mp3car.com/Silver_Metal...13&Click=29952
    It did not come with any wiring diagram. I am switching power for a 12v DC device.
    The terminals on the switch are labeled 1,2,3,4. What is the correct way to wire this switch?
    I am testing with a meter and can't seem to get it to work properly.

    Thanks for your help.

  2. #2
    Raw Wave
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    IMO items that have no info - especially when their site doesn't even have the info - is pretty **** poor. That alone has unfortunately often caused me go elsewhere. (And since I had a budget of $millions per year....)

    They don't even state if it's SPST or SPDT nor how the LED is connected
    If 3 terminals per side, it's probably a DPDT switch with the center pin "common" with one end the NC terminal and the other NO (normally closed and open respectively).

    While simple enough to experiment for the switch side (ie, center pin to either of the outer pins), on the LED side it should be +12V to one side and GND to the other, but neither to the centre if it is a DPST switch. That's what we call a short circuit.

    So test with a DMM, else ensure a suitable fuse or lamp to limit current if testing a load.

  3. #3
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    OldSpark, thanks for the insight. Here is a picture of the back of the switch with some labeling. They do indicate + and - on the center terminals which I assumed was for the LED. I wired the center terminals and the LED light does illuminate so I assume that is wired properly, but I couldn't figure out any combination of center terminal(s) w/ outer terminals. However I was able to get 1 switched 'action' -- If I wire a 12v power supply into terminals 1 + 2 (hot wire on 1, ground on 2) I only read 12 volts when the button is pressed. Other combinations I am able to get 12v reading with it simply wired in, but never anything when the button is pressed. Frustrating. Below is the image that might provide some insight hopefully.

    Name:  switch.jpg
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  4. #4
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    One other cool story, bro...
    The red plastic insert that labels the terminals in the middle comes out and in experimentation last night I took it out to examine it.
    So I have no idea if I put it back in correctly, meaning the labeling might now be flipped.
    And yah if I wire the center + and - terminals the LED lights up either way (regular or reversed)
    Awesomesauce.

  5. #5
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    "If I wire a 12v power supply into terminals 1 + 2 (hot wire on 1, ground on 2) I only read 12 volts when the button is pressed".
    Doesn't that meet what the switch is - a momentary push button (SPST)?

    Get in touch with the seller and get the data.
    I'm not clear headed enough to decipher the new info, and wrong info can be disastrous.

    Maybe someone else that knows will reply.
    Otherwise keep hassling the seller. Maybe they'll then realise that info is lacking for that product...

  6. #6
    FLAC SNOtwistR's Avatar
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    I think I would cut my losses and find a different switch with instructions. Do you need a latching type? If you only need 1 or 2 I have a bunch I bought from UK seller awhile ago very nice switch lighted I have lots of red, a couple of greens, and a couple of yellows.
    Durite by Gordon Equipments
    Name:  duriteswitch.jpg
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    On/off, push-push single pole switch, with 12/24 volt LED
    indicator and 4.8mm blade terminals. Snap fits into
    20mm diameter panel hole. 10 amp at 12 volts dc rating.
    Instructions included
    I have new in sealed package or some that have been installed for a couple of weeks. Was a project that went another direction. SNO

  7. #7
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    If I had to cut my losses for a $20 switch, I'd think I'd be doing it thru Consumer Protection agencies. And that's here where such things usually cost more.

    But I never spend that much on switches - I use simpler and smaller switches plus relays. (Many know my thoughts on carrying several Amps thru any switch.)

  8. #8
    ibf
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    However I was able to get 1 switched 'action' -- If I wire a 12v power supply into terminals 1 + 2 (hot wire on 1, ground on 2) I only read 12 volts when the button is pressed.
    Did you say you applied +12V to TERMINAL 1 and GND to TERMINAL 2? and you where getting 12V across it when you press the button?

    Assuming its a weak supply or has some sort of protection it sounded like you are shorting the supply and then un-shorting when you press the button. You may have burnt out the contacts.

    I think this is what you have here :

    -/+ = LED supply
    1/2 = Shorted when switch is unpressed
    3/4 = Shorted when switch is pressed

    3 and 4 is what you need. Pressing the button harder and firmly might do the trick? unless the switch is broken.


    The red plastic insert that labels the terminals in the middle comes out and in experimentation last night I took it out to examine it.
    So I have no idea if I put it back in correctly, meaning the labeling might now be flipped.
    And yah if I wire the center + and - terminals the LED lights up either way (regular or reversed)
    Something is wrong there if you were able to light up the LED with reverse polarity unless its meant work like that but I doubt it.

    As for the red plastic, check your previous photo, theres a small plastic bit that sticks out next to the TERMINAL (-) That might be a clue.

    When you have a switch with no data never use a real supply, a multimeter set to continuity is enough to give you plenty of clue.
    Leave the switch unpressed, find the terminal pairs that would give you a continuity, in this case its most likely 1 and 2
    Press the switch then find the terminal pairs that would give you continuity, in this case 3 and 4

    I agree with oldspark, there should be a full datasheet to go with it, you shouldn't have to go through this trouble.

    Good luck

  9. #9
    ibf
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    A quick image google and I found a similar switch to yours which is another clue

    http://www.frozencpu.com/products/im...ml?id=5nXeuX2W

    http://www.google.co.uk/search?hl=en...F4TK0QX4iIGgDQ

  10. #10
    Raw Wave
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    Now how difficult would it be for <the unnamed site> to provide THAT diagram on the switch's webpage?

    Nice find ibf. It's exactly what I was looking for, but I couldn't recall the "vandal" name/description, and google images is pretty poor at matching tech things & drawings. (Tineye is far superior for that.)

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