Fastest Way to Hack RC Car H-Bridge

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About: Electrical Engineer

Intro: 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




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    39 Discussions

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    BiswajitN4

    2 years ago

    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

    IMG_8355.JPGIMG_8352.JPG
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    SimoS4

    2 years ago

    thinks for info goood job men

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    Dear HUSHAM SAMIR I want circuit daigram for following circuit picture

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    arjun menon

    3 years ago on Introduction

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

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    arjun menon

    3 years ago on Introduction

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

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    DarkL1

    3 years ago on Introduction

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

    1 reply
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    Husham SamirDarkL1

    Reply 3 years ago on Introduction

    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).

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    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?

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    MichaelF6

    4 years ago on Introduction

    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
    1 reply
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    Husham SamirMichaelF6

    Reply 4 years ago on Introduction

    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.