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Topic: Rc car vs Arduino (Read 1 time) previous topic - next topic

Keits

Hey!
Just finished my new project: Wireles PS2 controller contreolled RC car.

So, I was driving around like ~5 minutes then unplugged DC plug from jack, and it was quite hot, but when I touched the 2 capacidors and voltage regulator?, they were very hot! Here, made a Picture:



Setup: made sheild for controlling 2 motors, rear motor and front one for steering. it uses 2 H bridges, one on chip(L293) and one made out of traistors. It uses 9.6V Ni-Cd battery.

Why components getting so hot? Motors drawing too much power? It's not safe to keep using this setup? What should be the best solution to change it?

Now as I'm writing this I think I can power rear motor directly via L293, may that help?


Thanks,

Onions

How were you connecting up the motors? Directly to an arduino pin will definately break it; depending on the motor current draw, it could be drawing too much for the voltage requlators. Usually (always) the motors are driven from the pins of the motor driver IC, which is connected directly to the battery for power. Drawing the current from the arduino will almost definately break it - motors can draw a lot of current! Post up some schematics of everything you have and where it is connected, then we can see...

Onions.
My website: http://www.harryrabbit.co.uk/electronics/home.html Up and running now! (Feel free to look round!) :D

Chagrin

The difference between the battery voltage (9.6V) and the regulator's voltage (5V) multiplied by the current is given off as heat by that regulator.

If you look at the datasheet for your L293 you'll see how to connect power from the battery directly to the L293's Vcc2 to power the motors and then you won't have all that current going through the regulator on the Arduino.

Keits

Chagrin, yes I'm going to try that... connect power directly to 293D


To Onions, as stated in the first post I used H-Bridges to control motors, but I made a schematic with Fritzing:


Onions

As far as I can see, the schematic looks good. Personally though, I'd use another motor driver IC for the second motor, rather than a transistor h-bridge. The IC appears to have room for 2 motors, so you can control both motors with just the one IC. This will remove the need for extra components.

Onions.
My website: http://www.harryrabbit.co.uk/electronics/home.html Up and running now! (Feel free to look round!) :D

Keits

Onions, I need 2 H-Bridges because it's not good to power front motor(for steering) with so high current, if I use external power source for L293D.

Onions

Onions, I need 2 H-Bridges because it's not good to power front motor(for steering) with so high current, if I use external power source for L293D.

The motor will only draw as much current as it needs, nothing more. As long as you provide it with the correct supply voltage, it will not blow. V/R=I. If the motor needs 5 volts, and has a 5 ohm coil, it will draw 1 amp of current. If it needs 5 volts and has a 10 ohm resistance, it will draw 0.5A (500mA). As long as you keep the voltage correct, the current will be fine.

Onions.
My website: http://www.harryrabbit.co.uk/electronics/home.html Up and running now! (Feel free to look round!) :D

Hey Keits,
           Im working on a similar project. Im going to control my rc car from my android. Im in the process of ordering two h bridges. Did the L293D work well for you? did you need a heat sink? thanks

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