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




MichaelF623 days ago

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

10694846_10204606363700027_1334476234_n.jpg
Husham Samir (author)  MichaelF622 days ago

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.

bakermiro2 years ago
I'd replaced with L293D
Husham Samir (author)  bakermiro2 years ago
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

plz help me.

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

Husham Samir (author)  mohamedbenayad2 months ago

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 ?

inawaz3 months ago

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

Husham Samir (author)  inawaz3 months ago

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.

RBA20004 months ago

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?

parts_view.jpgrx_ clone_chip.jpg
Husham Samir (author)  RBA20004 months ago

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

how can i make a remote control for this chip
Husham Samir (author)  nishu thakur1 year ago
you can download the RX-2 data sheet attached in this article ,it might be useful to you.
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
Bassem Adel2 years ago
can you show me the design of this circuit please
Husham Samir (author)  Bassem Adel2 years ago
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..
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
FI41YAUH3XMPCGR.MEDIUM.jpg
Husham Samir (author)  Bassem Adel2 years ago
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 .
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)  Bassem Adel2 years ago
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).