What is the best way to control a 12V DC motor?

Discussion in 'General Electronics Chat' started by swiftmamba24, Dec 18, 2013.

  1. swiftmamba24

    Thread Starter New Member

    Dec 18, 2013
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    Hi,

    So this is a two part question. I just recently purchased a 12V DC motor, http://www.pololu.com/product/1447, and it can draw up to 5A and 300mA free run. I'd like to know what the best way to control it is?

    I've got an arduino board and I was going to it through a transistor as a switch and then a potentiometer to control the speed. However, I only have 1/2W 5K and 10k pots and I'm unsure if they will be able to handle the current draw from the motor.

    On another note, should I control this motor with a PWM signal? Why not just a direct 12V?

    Thanks!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Why not? If you want to run it at the maximum rated rpm.
    What is your intended purpose for the motor, this will depend on what type of control is suitable?
    Max.
     
  3. swiftmamba24

    Thread Starter New Member

    Dec 18, 2013
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    Hi Max, I'd like to use it for a plastic filament extruder. I don't intend on running it at its maximum rated rpm.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Then you can pick up a cheap PWM controller from ebay or design a more sophisticated controller using the encoder fitted to the motor for servo feedback?
    Max.
     
  5. swiftmamba24

    Thread Starter New Member

    Dec 18, 2013
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    I guess what I'm most confused about is what is the benefit of using PWM? Is there an advantage over simply connecting the two terminals to a 12V power supply with a potentiometer?
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Potentiometer or variable resistor is very imprecise control also the potentiometer or variable resistor would require to be rated for the maximum current of the motor.
    Max.
     
  7. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    I used to use PWM to control the DC motors in model trains. I could get them to move incredibly slowly... I mean minutes per inch.

    PWM is something your Arduino is incredibly good at. It is also the most efficient way to go, your controller will run very cool. If there's a pot there you'll probably need to mess with a heat sink.
     
    Metalmann likes this.
  8. swiftmamba24

    Thread Starter New Member

    Dec 18, 2013
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    Fantastic, thanks guys, pwm it is
     
  9. MaxHeadRoom

    Expert

    Jul 18, 2013
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    There is also the dual SCR's in a bridge to the motor, or use a triac in the AC side of the bridge, one advantage to this is low component count and no separate DC supply required.
    But with the cheap price of PWM from China, it may not be worth it now?
    Max.
     
  10. tshuck

    Well-Known Member

    Oct 18, 2012
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    Those motors are great. I've built a few control systems around those motors using PWM to control them with good results.
     
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