Introduction: Fastest Way to Hack RC Car H-Bridge

Picture of Fastest Way to Hack RC Car H-Bridge
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.
My Regards
Husham




Comments

BiswajitN4 (author)2016-04-18

Hi,

I have receiver of rc car, but i don t have Transmitter remote. How to make of this?
How to make dual H- Bridge RX -2 Transmitter?
Can you send the diagram of the remote?
Thanks
Biswajit

SimoS4 (author)2016-04-14

thinks for info goood job men

laith mohamed (author)2015-12-31

Thanks for information.

Abdullahkhangandapur (author)2015-12-26

Dear HUSHAM SAMIR I want circuit daigram for following circuit picture

arjun menon (author)2015-07-03

i have a controller and its working but i don't know how to connect the wires to the board

arjun menon (author)2015-07-03

sry i have a board

arjun menon (author)2015-07-03

can you help me mr. husham i want to make a rc car. i have abord bu idon't know what to do

arjun menon (author)2015-07-03

arjun menon (author)2015-07-03

arjun menon (author)2015-07-03

DarkL1 (author)2015-04-05

I have a rx2b and a tx2b, how can i control two motors with those? (Just turn them on not giving them direction)

Husham Samir (author)DarkL12015-04-07

Check the RX-2 datasheet attached in this article (page 9 &10 ) ,for example take the output from backward and connect it to one transistor connected to the motor .

just search this in Google (control motor using one transistors).

imrank9 (author)2015-01-23

i want to made a rc car circuit not controler

imrank9 (author)2015-01-23

i want to made a rc car circuit not controler

imrank9 (author)2015-01-23

i want to made a rc car circuit not controler

imrank9 (author)2015-01-23

i want to made a rc car circuit not controler

goldenshuttle (author)2015-01-11

Mr. Hisham, good hack. I have receiver and transmitter in good shape still working. Is there a way to modify it to control speed ? I mean fix one motor on a pot to change the speed of the other one. then we get one motor only but with speed control ? is it possible?

arshdeeps164 (author)2014-12-12

Sir can u give me circuit of this model

MichaelF6 (author)2014-09-07

In my RC there's also at least one H-Bridge, but another chip. Its a Nikko 20610 i guess, but can't find datasheets etc for that.

How can i determine, which pin is which? The layout is single layered, so all connections could be seen on the backside

Husham Samir (author)MichaelF62014-09-08

Hi

I couldn't find any data sheet for this chip ,so try to trace the connection from the Motor-----Transistor-------chip

you might find a resistor in the way .

this is the required route to start the H-Bridge.

bakermiro (author)2012-06-28

I'd replaced with L293D

Husham Samir (author)bakermiro2012-06-28

yes I use L293D and it is a power full H-bridge chip but it's not easy to find in my country that's why I am looking for more options from electronic scarab.

CAN I REPLACE RX-2 BY RX-3E

mohamedbenayad (author)2014-07-21

plz help me.

I want to change h bridge by L293d and i d not know how?

Hi

Read the info in below link carefully ,it will help you to understand how to connect L293D ,make sure that your DC motor take small current .

http://www.cambierobotics.com/HTML/Robotics/L293%20Motor%20Driver%201.pdf

thank you

can i ask another question ?

I am student and my graduation project on robot vehicle by rx-2b.

so can you help me ?

inawaz (author)2014-06-07

Plz help me in yours above circuit where the output of receiver is connected ?

Husham Samir (author)inawaz2014-06-11

Each output of the receiver chip connected to a resister then to the transistor base of the H-Bridge.

I ignore the receiver chip and connect 4.5 volt with a resister in the way to the H-Bridge.

Do a search about H-Bridge to understand how it works.

RBA2000 (author)2014-06-01

I have a new bright Monte Carlo but with a different chip then the RX-2 (see picture). Any idea how to connect this one?

Husham Samir (author)RBA20002014-06-02

The problem that there is no number mentioned for this chip so it difficult to get the data sheet.

nishu thakur (author)2013-08-03

how can i make a remote control for this chip

you can download the RX-2 data sheet attached in this article ,it might be useful to you.

MohitJindal (author)2013-01-19

I am planning to buy a new DC motor driver board which can run 5amp motor but I don't know how to connect it with Atmega 8A chip. Please see the pdf I attached for Atmega 8A.

Here are the 7 pins in DC motor controller:-

Pin No. Pin Functionality
1 GND Ground
2 IN-1 Logic input for the motor direction.
3 Diagnostic 1
(DG-1) Output pin with logic 1 output in normal operation. Represents side of the internal
H bridge corresponding to IN-1. Pin is pulled to logic low by the motor driver in
case of over temperature or overload due to short circuit.
4 PWM Used to apply Pulse Width Modulation to control motor velocity
5 Diagnostic 2
(DG-2) Output pin with logic 1 output in normal operation. Represents side of the internal
H bridge corresponding to IN-2. Pin is pulled to logic low by the motor driver in
case of over temperature or overload due to short circuit.
6 IN-2 Logic input for the motor direction.
7 CS* Current Sense output to measure the current flowing through the driver

Basem Salep (author)2012-06-28

can you show me the design of this circuit please

Husham Samir (author)Basem Salep2012-06-28

If you are asking about transmit/receive circuit ,I attached the PDF datasheet which is contain all the circuits.but if you mean the H-bridge circuit I suggest you to use L298D dual H-bridge driver ,it can drive two DC motor from one single chip..

Basem Salep (author)Husham Samir2012-06-28

1- why did you use the transmit circuit must it be in the remote contro?
2- what is the difference between the two circuits in the picture.i see that contains the same parts with limit components are they equals ?
3- what is the type of these transistors ?

4- what is this component ( i attached the photo )
Thank you Eng. Husham Samir

Husham Samir (author)Basem Salep2012-06-29

Hi Bassem
1- I didn't use transmit circuit but i'm just saying if you are interesting in TX2/RX2 chip you can read the attached data sheet.
2- the two circuit will do the same function but with different design
for the small component circuit there is no safety in this design ,so if you made a mistake by connect positive for forward and backward in the same time you will burn the circuit.
check below web site for H-bridge design.
http://talkingelectronics.com/projects/H-Bridge/H-Bridge-1.html
3- 8550 PNP , 8050 NPN
4- ferrite cores variable inductor .

Basem Salep (author)Husham Samir2012-06-29

ok i will make the design number 2
1- have i do this circuit twise the firsit ( forword & backword ) and the second
(right &left) ?
2 - have i connect the two lines A & B to the RX2 ?
3 - which one of A&B (backword and forword ) ?
sorry about my many quetions

Husham Samir (author)Basem Salep2012-06-29

1- yes you should make two circuit, that's why I suggest you to use L293D or L298 because with one IC you can control two DC motor .
2- if you want to make H-bridge circuit only , no need for RX-2 .
3- well it depend on how the polarity of motor connected (up to you).

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