how do i hook up a spdt?

Discussion in 'General Electronics Chat' started by ShockBoy, Jan 27, 2010.

  1. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    my schematic shows nc/no output, along with it's input;;that's three connection points. then i have the two connection points straddled by a diode. That makes 5 connection points. My relay has 7. I remind you all that I am new to electronics. how do i hook this up?

    Thanks for the assistance.
     
  2. Paulo540

    Member

    Nov 23, 2009
    188
    0
    Does the relay have a remote switch terminal pair? Maybe that's the other two. Or, it might have a second set of contacts which is possible.

    Anyways, the two pins 'straddled' by the diode are the coil make sure to observe proper polarity. If there is a symbol on the top or side of the relay, you will see which pin goes where. There will be a common and it will be touching another contact while spaced away from the other in the diagram. The one it is touching will be the NC and the one it is spaced from will be NO.

    Its hard for me to describe in pure words but I hope this makes sense.
     
  3. VoodooMojo

    Active Member

    Nov 28, 2009
    503
    53
    SB,
    can you post your schematic or perhaps the relay part # ?
     
  4. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    Ya, the two small 'mounting looking posts'. I am confused. look at my pic post of what i've got.
     
  5. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    data is the datasheet I've found and relay is the schematic icon of the relay connections. Totally confused.
    Thanks.
     
  6. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Here, I drew the coil and contacts into what it should look like:

    [​IMG]

    Try using a meter set to measure Ohms between the two coil pins, and then between the two COM pins and the NC pin. You should read nearly 0 Ohms between the two COM pins (connected by red) and the NC pin. You might measure a couple hundred Ohms between the coil pins.
     
  7. ShockBoy

    Thread Starter Active Member

    Oct 27, 2009
    186
    0
    Do i need to run both of the com points or is it an either/or situation?
    Once again Sgt. Thank You.
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    As long as you have at least one of the COM terminals/pins connected, you're fine.

    There are a couple of COM pins to give board designers flexibility in where they can connect the COM signal. The basic layout is similar to an industry standard relay design.
     
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