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Newbie help with relay card

Discussion in 'General Electronics Discussion' started by towijo, Feb 16, 2013.

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  1. towijo


    Feb 16, 2013

    I want to use a relaycard to control a 12VDC/180mA device using a 5VDC/20mA signal wich i think is pretty basic stuff :) but im getting kindof confused on how to connect things.

    The relay card im using is B197 - Relay card 12 V/DC (Kemi electronics)

    It has three input pins: "MINUS", "IN", and "PLUS". and specifies the following:
    * Between "MINUS" and "PLUS": 12 VDC
    * Between "IN" and "PLUS": 3 to 12 VDC > 5mA

    and it has a relaycontact with max 30VDC/3A

    So Im going to tell you what i think and then you can correct me :)

    Step 1: Connect a 12 VDC powersource to "PLUS" and "MINUS" which will be used to supply "operating power".

    Step 2: Connect my weak output signal between "IN" and "MINUS" to be able to control the switch

    Step 3: connect the device curcuit (which also is powered by the 12 VCD powersource) through the relaycontact

    Would this be correct?

    My main concern is if the relaycontact is acting as a powersource or just a "dumb" curcuit switch?

    Thanks in advanced for helping out!

  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    That should read:
    * Between "IN" and "MINUS": 3 to 12 VDC > 5mA
    Step 1: O:K.
    Step 2: O:K:
    Step 3: O:K:

    The relay contact is just a switch, no power source of its own. You need to supply external power for the load circuit
  3. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Spot on, Harald.
  4. towijo


    Feb 16, 2013
    Ok thanks for eliminating my doubt! and yes, controlling signal between "minus" and "in".
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