Controlling DC motor with relays

Discussion in 'General Electronics Chat' started by adrixas, May 19, 2016.

  1. adrixas

    Thread Starter New Member

    May 19, 2016
    1
    0
    Hello guys,

    Is it possible to control a dc motor both ways using two relays? With only one control wire, that changes from earth and12V?
     
  2. profbuxton

    Member

    Feb 21, 2014
    233
    68
    Yes. But you need limit switches and will only continually go forward and reverse when 12 v is on.
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
    1,103
    Surely the motor needs at least three states: Off, Forward, Reverse? Don't see how you'd do that with only one control wire unless you could cycle through the three states.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    The direction control can indeed be done with two 12V coil, SPDT relays and one control wire.
    Connect each relay wiper contact to the motor.
    Connect one relay NO contact to the supply voltage and the NC contact to ground.
    Connect the other relay NC contact to the supply voltage and the NO contact to ground.
    Then with the motor will go one-way when both the relays are energized and the other way when they are both de-energized.

    But if you want to be able to also stop the motor with those relays, then you need to control the relays with separate wires.
     
  5. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,788
    945
    The need for an "off" state complicates things.

    Here is my suggestion using two relays
     
  6. twohats

    New Member

    Oct 28, 2015
    9
    1
    Here is my suggestion using two relays
     
  7. twohats

    New Member

    Oct 28, 2015
    9
    1
    12v motor switching.jpg My version of two relays.
     
  8. MrSoftware

    Active Member

    Oct 29, 2013
    500
    122
    If you don't need off-state, then you can do it with a single DPDT relay as shown below. Connect your source + and - to the "COM" pins. Connect the left NC to motor + and right NC to motor -. Connect the left NO to motor - and the right NO to motor +. Connect one side of the coil to ground and the other is your signal. The motor will always be on, but when you give power to the coil the motor will reverse.



    [​IMG] [​IMG]
     
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