DPDT switch for reversing polarity

Discussion in 'General Electronics Chat' started by hpmor, Aug 7, 2008.

  1. hpmor

    Thread Starter New Member

    Aug 7, 2008
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    I use a DPDT switch to swap the polarity of the motor.
    The diagram looks like this. (file is attached herewith)

    What I need is to stop the motor when it goes in both direction.
    I want to stop the reverse and will continue forward and stop the forward and will continue on reverse.

    I know it can be done by micro switches but any one have circuit diagram for that.
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    A center-off DPDT switch will allow you to stop. The configuration will be listed as On-Off-On.

    John
     
  3. hpmor

    Thread Starter New Member

    Aug 7, 2008
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    well i am using that one

    but I want to break the circuit with a micro switch so when motor move up it will hit the micro switch and will stop and only be move down
     
  4. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    This is a new ball game. With one NO push button switch, two SP DT Micro switches and one 4P DT relay it can be done. My version you hit start sw. motor[ with gear reduction ] turns untillbump on cam hits msw; moror reverses untillcam hits home msw;then stops.
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Have a look at the attached.
    The first schematic is basically what you currently have; although instead of two separate SPDT switches, you have a single DPDT switch.

    The 2nd schematic adds limit switches so that the motor stops when the desired maximum limit is reached.

    The 3rd schematic is different; it's using a single DPDT switch to automatically reverse the motor when the limit is reached.
     
  6. hpmor

    Thread Starter New Member

    Aug 7, 2008
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    thank you for the response

    Can the limit switches can be placed into the diagram I posted. I try to do that but it won't work. Or may be there are different type or DPDT switch which has default mode
     
  7. SgtWookie

    Expert

    Jul 17, 2007
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    See the attached.

    Note that if you have the limit switches on the wrong ends of the actuator, it won't stop the actuator; but it will prevent the actuator from running in the direction that it needs to. If you find yourself in that predicament, either reverse the wiring to the motor, move the limit switches to the opposite ends of the actuator, or swap the limit switch connections on S1.
     
    Last edited: Aug 7, 2008
  8. hpmor

    Thread Starter New Member

    Aug 7, 2008
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    Thank you very much. I appreciate.
     
  9. team_nes1

    New Member

    Jan 18, 2009
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    I bet you could use the wiring diagram for more than just reversing motors. How about reversing a pair of speakers? This way, you can hear sound out of the correct channels when your speakers are behind you. And if you wanted the correct channels when the speakers are in front of you, just flip switch.
     
  10. kathapurushan

    Member

    Dec 17, 2008
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    hpmor,
    Do you need to run the actuator in both directions continuosly ? i mean one or more rotations clockwise, then one or more rotations anti-clockwise, and so on ? If you intend to do so, you may incorporate a 555 ic in astable mode with 50% duty cycle, 2-pole 2-way relay and appropriate driver for the relay ? A simplified 'block diagram' is attached for reference.
    If you need to stop the actuator in between the reversal of direction of rotation, you may add another 555 ic in astable mode along with a 1-pole 1-way relay in between the actuator and the power supply to the actuator. Please note that i have not considered any feedback from the actuator and the design is simply based on 'time' only.
     
  11. druines

    New Member

    Mar 18, 2009
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    I'm new to this but have a question about this topic. I have two 12 v DC motors in the same circuit that need to be able run forwards and backwards simultaneously. My current set up is a SPST switch - center off, up and down for different directions - going through two SPST relays with a diode across two of the terminals to prevent current flow in the wrong direction. I also need two microswitches to prevent movement beyond a certain point in each direction on one motor which cancel the entire circuit. Total circuit load is 10 amps max. (fuse value). (See attachement for details). Question is, as long all the parts are rated at >10 amps (e.g. switch, etc) can I replace this set up with a DPDT switch wired to reverse polarity or maybe a switch running a DPDT relay wired in the same way to reverse polarity? The reason for the change is to reduce parts, weight and wiring. The switch and no relay I understand but how to make this work with a DPDT relay I don't know. Any help out there?
     
  12. SgtWookie

    Expert

    Jul 17, 2007
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    Druines,
    I would not recommend it for an aviation application.
    Your schematic uses two SPDT relays so that the stress on the limit switches is low, and you get the benefit of braking action due to the motor's windings being grounded when the relay's coil de-energizes.
     
  13. howpedestrian

    New Member

    Apr 12, 2009
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    Hello I am having trouble with understanding this relay: PCLH-202D1S

    I am very new and need help controlling a 12v motor... need it to stop, start and reverse.

    Please help.
    Thanks
     
    Last edited: Apr 12, 2009
  14. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I'm not sure of your physical arrangement of the motors and their loads, but if they are not mechanically sync'ed, you are going to have problems using one pair of limit switches when powering them off the same relay(s). One motor will always run at a slightly different speed, an eventually not stop where you want.

    Ken
     
  15. OFI

    New Member

    Apr 25, 2009
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  16. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    First, what are you trying to wire to the switch to on his dump trailer?

    Ken
     
  17. Wendy

    Moderator

    Mar 24, 2008
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    Something else, if you took Wookies schematic and changed S3 and S4 to 2P switches, you could short the motor instead of just opening the power supply path, which is a form of dynamic breaking.
     
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