Relay or electronic switch

Discussion in 'General Electronics Chat' started by andrewwallaceuk, Mar 10, 2016.

  1. andrewwallaceuk

    Thread Starter New Member

    Oct 20, 2015
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    0
    Hi Guys,

    Complete newbie here so apologies for my ignorance in advance.

    I have a project on the go at the minute and I'm a bit stuck. Basically I have a control board which operates a relay. I want this relay to operate a mechanical actuator. The problem is I need a neutral position with the actuator otherwise it is going to burn the motor out. At the moment I only have normally open or normally closed positions which I use to drive the actuator in one direction or another.

    Is there such a thing as a three position relay in which I can have one position with no current flowing?

    Thank you for your time in advance.

    Andy
     
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    A K-form relay has a center off position.
     
  3. andrewwallaceuk

    Thread Starter New Member

    Oct 20, 2015
    2
    0
    Will I be able to toggle between two other positions?
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    1,251
    It sounds like the relay performs the reversing function, probably with DPDT (double-pole, double-throw) contacts. If so, a common solution is two SPDT relays controlled by a center-off switch.

    ak
     
  5. bwilliams60

    Active Member

    Nov 18, 2012
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    Would something like this solve your problem?

    Reversing-a-Motor.png
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Yes, two separate relays, so one is driving the motor one way, no relays activated no movement.
     
    Last edited: Mar 11, 2016
  7. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    The OP said that the relay was to control a "mechanical actuator." I take that to mean that the motor direction is controlled by the position of this mechanical actuator and that the actuator makes and breaks the electrical connections to the motor to control its direction.
     
  8. alfacliff

    Well-Known Member

    Dec 13, 2013
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    a reversing relay usually has a mechanical linkage to prevent both sides from energising at the same time, which woud be bad.
     
  9. MrSoftware

    Active Member

    Oct 29, 2013
    500
    122
    A couple of relays, or an H-bridge. Or you could use limit switches to stop the motor when the actuator reaches its end points. Combine with a fuse of some sort in case it gets stuck somewhere in between.
     
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