DC motor controller

Discussion in 'The Projects Forum' started by thavamaran, Jul 22, 2009.

  1. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
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    Hi guys, im currently building robotic arm with dc motor control, i dont need it to be servo because its just an assignment. is it ok if directly plug in dc motor to pic and run it.

    or use a H-bridge driver. Why dc motor needs a driver? other than H-bridge driver, what are other types of drivers that could be used?

    So far i found out L297D is mostly used as H-bridge driver.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    If you connected it directly to a PIC, you will most likely kill the PIC very quickly. PIC I/O pins can only source or sink about 20mA each; and there is also a limit as to the total current a PIC may source or sink.
    An H-bridge will allow you to run the motor in either direction.
    Because microcontrollers cannot source or sink enough current to drive such heavy loads.
    You could also simply use a MOSFET or transistor as a current sink between the negative side of the motor and ground. However, this will not allow you to reverse the direction of the motor; for that you would need an H-bridge or a relay.

    No, an L297 is a bipolar stepper motor controller/driver. The L298 is used in conjunction with the L297 for higher powered stepper motors.
     
  3. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
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    Thank you wookie, Your explanation really make sense, but as you said L297 is for stepper, then which driver can be used for DC motor?
     
  4. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
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    Hi guys, i have fixed the entire robotic arm with DC motor and L293B H bridge driver and its working very very well. its fantastic. but the problem is, i need use a power supply, power supply in sense those huge power regulators which you can adjust the voltage you need, because if i use normal power cord which supplies 9V and i pull it down to 5V via voltage regulator, the current is not enough to run the robotic arm, then i used 9V battery and yet its not enough.

    the whole robotic arm only functions if i supply them with huge power supplies. the dc motor im using doesnt have a datasheet and i simply supply them with 5V across H-bridge. its those small DC motor for those toy cars. i dont really get the problem
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,176
    397
    " toy cars " , current demand can cover wide range, 50mA to 10A or more. The RC cars beeing the thirstiest. Can you measure loaded current demand, using 6V lantern battery or similar??
     
  6. thavamaran

    Thread Starter Active Member

    Feb 21, 2008
    67
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    "using 6V lantern battery or similar", im sorry but i dont really get your idea, do you want me to measure the current across the motor during operation of the motor?
     
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