DC Motor Help

Discussion in 'The Projects Forum' started by Judith335, May 20, 2011.

  1. Judith335

    Thread Starter New Member

    May 20, 2011
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    Hey Everyone,

    I got a DC motor that I want to use in a little project of mine but I am not very experienced in DC motors. I would greatly appreciate a little direction on what kind of motor this is and what signals it will need to move/control it. Obviously no one will know exactly about power/pin assignments but I am just looking for some direction. I attached 2 pics of it. It has a 7 pin connector on it.

    Once again thanks for your help.
     
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  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    right now it is a disassembled motor.

    It has a rotor and rotor windings, but we cannot see the outer part. The Stator is what it is called. It might be magnets, or it could be more wire coils. You did not show that part. I'm going to assume it is magnets, since I think you would have shown it if it had lots of wire coils inside.

    Automotive origin? 12 volt DC driven then. The extra pins in the connector will go to the commutator(the small stripped copper ring above your thumb in the first picture.)

    Most likely places the coils in parallel, or series to control speed, or there might be electronic components hidden beneath that area that comprise a PWM or voltage divider network.

    Need more info....
     
  3. Judith335

    Thread Starter New Member

    May 20, 2011
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    Thanks for the quick reply.

    You were right in your assumption that there are magnets in the housing and that its 12VDC automotive. I included that picture.

    I also did a pin out on the connector. The connector is a 8-pin connector with the 4th pin not attached.

    Pin 1 --> Commutator
    Pin 8 --> Commutator

    Pin 2 looks to be a common with it showing 18.7K thru pins 5 and 6, and 1.9K thru pin 7.

    Pin 5 to 6 is 37.4K
    Pin 5 to 7 is 20.6K
    Pin 6 to 7 is 20.6K

    That's the only connections I could find though with nothing on pin 3.
     
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  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    So right now, all you need to do is.

    1. put it back together. :)

    2. Apply 12 volts to pins 1 and 8.

    3. Mount it in your project.


    If you need to control its speed, then we can point you to various discussions about PWM control circuits. You basically send it 12 volts in a series of on/off pulses. The longer the 'off' time between 12 volt pulses becomes, the slower the motor turns.
     
  5. Wendy

    Moderator

    Mar 24, 2008
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  6. Judith335

    Thread Starter New Member

    May 20, 2011
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    Is there any way I can control position with this motor?
     
  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Only with EXTERNAL sensors that look at gear teeth or other portions of its driven mechanism. Position sensing, such as you find in servos/synchros is not possible with this type of motor. It has no position output capabilities. you will have to utilize Hall effect/magnetic position sensing or some type of motion counting circuitry.

    What are you trying to do? We can be much more helpful than this mere generic information digest service I'm providing now. If you can give us a more specific application oriented goal you are trying to accomplish, we can often make very specific recommendations that relate DIRECTLY to that use.
     
  8. Judith335

    Thread Starter New Member

    May 20, 2011
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    I am going to use this to open and close a valve. I just wasn't sure what pins 5, 6 and 7 do and didn't know if that could somehow be used for positioning. The unit I have has a Hall effect sensor down on the gearing, but I wasn't sure if the motor could sense position as well. Your help has been great, I am going to put this back together and start playing with it.

    Thanks again! This seems like a wonderful forum and I am excited I found it.
     
  9. CDRIVE

    Senior Member

    Jul 1, 2008
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    Since limit switches might be problematic for this application, perhaps 'locked rotor' sensing would be more applicable.
     
  10. KJ6EAD

    Senior Member

    Apr 30, 2011
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    Does this mysterious DC gear motor have a name? Brand and model number?
     
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