Monday, July 2, 2012

Fastest way to Hack RC Car H-Bridge

Fastest way to Hack RC Car H-Bridge
  • RX-2.JPG
  • RX-2.png
  • RX2 2.JPG
I have some broken small RC car without remote control and I was interesting to hack the H-bridge of these car and connect them to micro controller circuit  in order to make for example a line follower robot or obstacle avoidance robot.

The common circuit of RC car consist of :
1-Receiver circuit which is define the frequency that the car will work on( for example 40Mhz or 27 Mhz).
2-Controller chip (De-Multiplexer circuit).
3-Dual H-bridge circuit for driving two DC motor (one for backward ,forward and the other for the steering).

you can see that from the above picture,  it's a little complicated to find the base of transistors that will make the motor  work ,also it will take  a lot of time, so instead of that I download datasheet of the controller and from chip pins diagram we can trace the H-bridge pins directly.

RX-2 Controller Chip:
RX-2 is a five function receiver chip work as a De-multiplexer and the multiplexer of this chip called TX-2 which is located in the remote control of  the RC car .it's a very interesting IC and compatible with RF and infrared (check attached datasheet ).

Now from the pin  diagram shown in the next picture  you can locate the pins of H-Bride  (PIN 6 ,7 for right and left ) and (PIN 10,11 for backward and forward).
By connecting +5 volt to these pins you will be able to control the motors but be careful don't connect 5 volt to right and left or backward and forward on the same time ,you might burn your circuit (depend on circuit design) .

Now you can remove RX-2 chip and connect the H-bridge pins to a micro controller  but it's better to connect a 330 ohm resistor between them for current limitation.

if you like or find this tutorial useful to you , please vote for it in the Electronics Tips & Tricks contest.

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