Control 5v chip

i'm trying to control a rc car that has 4 inputs that need 5V in order to operate the motors.
I just need to feed 5v on each of those pins (with arduino) to controll the motors.
Using arduino i connected one pin (10) set it to OUTPUT and then just digitalWrite HIGH on that pin, ok , everything works.
But how can i protect the arduino pin, to avoid destryoing it ?

NOTE: (arduino is operating in a different power source from the rc car, two different batterys only both grounds are connected)

An Arduino pin doesn't have enough current (amps) to drive a motor under load. For that you'll need a MOSFET.

Look for "Logic Level MOSFET" at your supplier (it has to be logic level to work with an Arduino).

If you are using the H-bridge inputs that were in the RC car to begin with, and you are certain that they are operated by applying 5 V, you shouldn't have to worry about the Arduino outputs. But just to be safe you can try placing 330 ohm resistors in series between each output pin and the H-bridge input pin, to protect against excessive current draw. If the car works well, leave the resistors in place.

Be sure to connect the grounds together. On the RC car, ground is almost certainly connected to the negative battery terminal, as it is in the Arduino.

@ fungus it’s like jremington said, the rc car has the h-bridge and i just need to feed 5v to whatever pin i need to control :slight_smile:

@ jremington to avoid frying my arduino i first tried with a 5v power supply to feed each pin i need to control with 5v and everything worked well. Then tried with arduino, it “worked” (the car runs as i drive pins HIGH/LOW) but dunno why i saw some smoke coming from the rc car h-bridge board :\

I'm supplying the rc car h-bridge with one battery, and the arduino on a different one...
arduino's function is to provide 5v signal to control each pin (how can i know if i'm not trying to supply more amps than arduino can provide ? )

Read reply #2.
If you saw smoke coming from the H-bridge, it was probably destroyed.

I found that a resistor had a little plastic cover on one of his legs that got burnt.
What may be the causes ? Supplying 5v to that pin with arduino could cause that ?

too much current causes that.