RC-Car, H-Bridge --- Need Help


a few weeks ago I wanted to throw my old (more than ten years) RC Car away. But since I'm totally interested in arduino I wanted to give it a try.

So, fact is my motor (forward / backward direction) has to speed modes.

By direct connection to 4.8V DC (the batteries are a bit fuller: around 5 V)
It "uses"

  • in the first one: 0.6A and 4.8V
  • in the second one: 1 A and 4.5 V

I still have some L293D lying around. But I dont think they fit (with 0.6 A and peak 1.2 A, I think)

Has anyone done something similar? Is there a better way to control the direction of the motor?

THX to every helpfull answer.


If the car still works, why not use the existing components, there is a long thread here on doing this, I think it was titled 'Modding an RC car'

Duane B


Hi Duane,

the big problem is that the old PCB was totally covered with some kind of resin and so it was unuseable.

So I had it connected to the L293D. The Logic Power (+5V) came from the arduino and the motorpower came from the batteries (4.8V) But I have measured only <1V across the motor and current was 600mA.

I’m a bit confused about the voltage loss…

This is far from a definitive answer, but if the motor is running, it is also acting as a generator, generating a 'back emf' search the web for this term and it may explain why you see a smaller voltage drop than you expect.

Duane B.