L293D help (motors not running at same speed)

Discussion in 'General Electronics Chat' started by utilityhacker, Sep 15, 2014.

  1. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    So i'm using the l293D motor driver. The problem i'm facing here
    is when I connect the 9v battery to the whole circuit one of the
    motor spins slow and the other spins slight faster.
    Actually i want to make a robot and I'm using this circuit as a part of it.
    I changed the 9v battery with a new one but nothing happened.
    The motors are of 3v each.
    Pls help guys.
    [​IMG]
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,790
    945
    without a schematic of your circuit, helping will be mostly guess work.

    some troubleshooting checks to get you started. Motor or Driver? swap out your two motors and find out if the problem moves with the motor or is related to a driver output side.
     
  3. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    I interchanged the motor and the output pins but no luck
    I also tried another L293D but nothing happened
    (I attached a fritzing image file)
     
  4. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    Do you have proper schematics those fritzing renders are not exactly easy to read.

    Measure the voltage on motor power lines and report back.(If you can measure it).
     
    Last edited: Sep 15, 2014
  5. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    What do you mean "no luck" and "nothing happened"?
    Did the problem follow the motor when you changed things or not?

    A 9V battery will not operate a two motors for very long. For a 3V motor you could use a couple of AA or larger cells.
     
  6. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    i checked. its 2.5v 0n one motor and 1.8 on the other.
     
  7. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    Something is dropping the voltage,get a 9V adapter and use that.Battery will drain too fast.

    Wire it like this:
    [​IMG]
     
  8. tshuck

    Well-Known Member

    Oct 18, 2012
    3,531
    675
    Does the problem persist if you hardwire the enable/control lines on the L293D?
     
  9. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    Change to 9V alkaline battery or using two 1.5V alkaline batteries in series.
     
  10. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    Using a 9v adapter solves the problem.........
     
  11. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    this works too
    thanks
     
  12. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    That just proved the 9V can't work properly for motor, and it can't give you the really working test for a robot.
     
  13. crutschow

    Expert

    Mar 14, 2008
    13,016
    3,235
    What power source will the robot have?
     
  14. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    The 2x2 GND pins in the middle of chip are used as heatsink connection to the PCB.So you should have something better then wires connected to them.
     
  15. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    can you suggest something...??
     
  16. utilityhacker

    Thread Starter Member

    May 1, 2014
    40
    4
    4 AA cells
     
  17. ISB123

    Well-Known Member

    May 21, 2014
    1,239
    527
    You could take 1.5x1.5 cm Alu/Copper sheet and drill 2 holes and solder the wires to 2 holes.
     
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