I am using l293d in a line follower but recently I am facing a problem. my l293d motor driver is not able to power 2 300 rpm motors simultaneously while with one of the motors at a time it works perfectly fine. Earlier it used to drive both the motors at optimal desired speed but recently its posing the above mentioned problems. I have tried replacing the Motor driver and Arduino itself but nothing worked and I am still facing the problem.

  • What is your power source, is it able to supply the current for 2 motors? The L293d with proper heatsinking should supply .6A per channel which seems like it should be sufficient for a robot under minimal load. I would check the batteries! – Mariano Elia May 6 '17 at 17:26
  • yeah the power source is just fine .. I use a 12V-1A power adapter from the beginning . Earlier it worked just fine but recently this whole arrangement just got messed up with the motor driver failing to drive the 2 motors. – Somit Sinha May 6 '17 at 18:00
  • Do you have an earlier revision of the code? Could it be something software related? – Mariano Elia May 6 '17 at 18:09
  • I sense the code is all fine because the motor driver isn't able to drive the two motors simultaneously even when I directly connect them to the l293d outputs without taking any inputs from the Arduino . – Somit Sinha May 7 '17 at 7:58
  • Please post your code. I have seen this problem before, the OP claimed that it was a power/board problem and it turned out to be a bug in the code. – sa_leinad Jul 8 '17 at 11:16
  1. Check if both channels are working in either direction individually.
  2. Check the current draw under the load per motor using an Digital Multimeter as an Ammeter function.

The L293 is designed to provide bidirectional drive currents of up to 1A at voltages from 4.5V to 36V. 600mA per channel for L293D

  1. As long as your motors at drawing more than 600mA per motor, it should work fine.
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Check your power supply with a multimeter. Look out for voltage drops under load, or similar problems.

Also, make some tests with another power supply in order to find out if the one you're currently using is faulty or not. You say you've tried replacing the motor driver and the arduino, but not the power supply.

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