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L239D Motor Driver IC? Answered

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I saw some example circuits on how to control motors using L293D and arduino , Some included a lot of capacitors and some not at all.Which way is the correct one and what are the capacitors used for in the circuit.

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steveastroukBest Answer (author)2012-12-13

Its bad practice NOT to put caps on a circuit. They are there to stop noise being broadcast from the circuit.

Amateurs often omit them, then discover their computer's crash.

Your second circuit is correct, the first, and invitation to disaster.

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Bot1398 (author)steveastrouk2012-12-13

To provide the 5v to the L293D can use the arduino 5v directly

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steveastrouk (author)Bot13982012-12-14

The 293 needs a clean 5V supply for the logic, and a "motor supply" which MUST NOT be the same as the logic supply - the noise and current drain will kill the arduino.

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alikitty (author)steveastrouk2015-02-24

I know this is probably long forgotten about, but its worth a shot. Could you give me an idea of what kind of voltage regulator I would need to use to implement something like the second circuit?

Also, would you mind explaining a bit more about how I could connect the motor supply? I recently picked up this hobby, I love it, and I quickly realized the tutorials here (not at instructables, but in general) were similar to most programming walkthru's, full of bad practices and noobie mistakes!

Thank you!

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steveastrouk (author)alikitty2015-02-25

Both circuits are basically wrong. You don't use a regulated supply that feeds the micro and the sensors as well as a nasty horrible noisy motor ;-)

The micro and the sensors can use something like a LM7805 regulator.

Steve

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The Skinnerz (author)2012-12-13

Both circuits should work if you only have small motors and a reasonably powerful supply. However, it is always a good idea to add capacitors to smooth the input and output of the regulator, and put a 0.1uF capacitor accross the inputs of any ICs.

I think the capacitors on the inputs to the motors are to smooth a PWM output, and possibly as suppression for brushed motors to minimise interference with any nearby radio equipment.

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