Instructables
Picture of How To Radio Control DC Motors Cheaply
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For the people who don't know what a "VEX" is. It is a company that sells robotic parts and kits. They sell a "VEX" transmitter and receiver on their site for $129.99 but you can get a "VEX" transmitter and receiver for about $20 on "Ebay" and many other places.

The "VEX" transmitter is a 6 channel FM transmitter with 2 joysticks that can go up & down and from side to side. On the backside of the transmitter there are 4 buttons which control channel 5 and channel 6. The transmitter controls can be set to tank-style or arcade-style. The transmitter has a host of other features.

This makes it a very cheap way to remote control servos. The only problem is that you can only control servos motors and you need to buy an expensive $149.99 "VEX" microcontroller just in order to do that. That is until now!

Step 1: How It All Works

Picture of How It All Works
This low cost ($14.95) "motor interface chip" can be bought at: http://robotics.scienceontheweb.net The chip can decode the signals from the "VEX" receiver to control up to 8 motor's H-bridges and 1 driver. It can also receive commands from another microcontroller chip to control the motors. This interface chip uses 3 output pins to control a motor's H-Bridge. Two pins to control the motor's direction and one pin to control the motor's speed by using P.W.M.

The chip uses the input from the two buttons on channel 5 to control the input from the "VEX" transmitter left joystick so that it can control 6 motors. The chip uses the input from the other 2 buttons on channel 6 to lock in the high or low output on pin 14 of the motor interface chip.

The motor interface chip has the following features. These features may not work since a receiver may pick up a signal from anywhere. We assume no responsible directly or indirectly from using these parts. WARNING! NEVER USE THE REMOTE ON A ROBOT THAT CAN CAUSE DAMAGE IF IT GOES OUT OF CONTROL. If your robot goes out of transmitter range; the motor interface chip may shut down the motors and give control to a microcontroller if your robot is using one. This may also be true if you turn your transmitter off.

The motor interface chip does not use a serial port to
communicate with other microcontrollers. This means you can use a very inexpensive microcontroller chip to be the brains of your robot.

Putting a low on pin 2 will cause all the motors to operate at half the power level when using the transmitter.
 
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jobs9272 years ago
grasias por tus aportes Al1970 yo tengo un control vex al cual le sacare todo el potencial por favor diagrama con motores
it would be really cool to know how you could control an rc car successfully with a games console controller, has anyone posted about this yet? thanks rc tanks fan
sumanlama3 years ago
ma chukni ta kini lado kha
momomo683 years ago
I realize this is an old post- I'm having trouble finding how to control 5-6 dc motors w/ remote control because the links are no good anymore, any current info on the topic? Thank you.
haclil5 years ago
Anyone know why radio-controlled model (electric) trains aren't marketed? Seems like a good idea to me because: RC offers more commands than existing control systems; speaking of transformers, RC offers lower input voltages; should be easy to run several trains and keep each under separate control. I ask because I'm planning to build a model railroad.
evad haclil5 years ago
Because the latest in model train control is DCC- Basically, the track has a constant DC voltage, and AC signals from a controller are sent "on top of " the track voltage, and the engine has a receiver / decoder. They can be had with many channels. Some live steam and garden railway folks use R/C
kissiltur evad5 years ago
I wondered if anyone was doing that with trains. Thanks.
123KA kissiltur3 years ago
Wow thanks for this instructable I am building a robot for my son with some parts from
RC Tanks that I got from here. We didnt have the budget for all of the radio gear but this has really helps... Thank You.
akhile19964 years ago
 i am actully feeling bad as VEX is not present in ebay india.So please reccomend something else.
hey
i live in india too
where do u live?
i live in chennai
by the way my name is also akhil(aki)
For cheap RC gear go to
http://www.raidentech.net
http://www.hobbycity.com
http://dealextreme.com
They have pretty much everything you need

Ben
adam 1015 years ago
does the PWM come from the remote or a micro controller?
Al1970 (author)  adam 1015 years ago
Comes from the micro.
adam 101 Al19705 years ago
so you are saying i cant control speed remotely with this?
Br5475 years ago
Is this the same thing as the vex signal splitter that vex offers on there web site?
Al1970 (author)  Br5475 years ago
Hi: No. It is not make by "VEX" This chip can control up to 8 DC motors.
I NEED A HELP REGARDING MY PROJECT OF "RC HELICOPTER" I HAVE TO CONTROL THE SPEED OF FOUR DC MOTORS BY MEANS OF IR REMOTE CONTROL
Is it just me or is that "interface chip" a PIC16F uC, probably pre-programmed with your guess is as good as mine firmware?
hello
does anybody has the circuit diagram of this robot
http://www.robotroom.com/Sandwich.html
i really wanna make this
n don hav money to buy d book or the PCB
search "line follower" and I'll bet the sandwich curcuit is copyrighted but general line followers arn't
The Jamalam6 years ago
the front of the control looks like a face and the back looks like a pair of eyes :P
benthekahn6 years ago
I found a place to buy the Vex remote and receiver for $30.
Al1970 (author)  benthekahn6 years ago
You can get them on EBay for less.
chadsly6 years ago
This is really cool. I'm hoping to get the chance to turn my electric lawn mower into a remote controlled lawn mower. This should work well. The link on the second page worked, but when I click to purchase it, the link sent me to a web host. Can you check those links again?
Al1970 (author)  chadsly6 years ago
Hi chadsly: The links do work but it is a free web site so they work only when they want to LOL. The link would take you to PAYPAL. You can just go there and send the money to: arealperson@hotmail.com At some point do you want to give the lawn mower a brain?
alexhalford6 years ago
Can PWM be used on AC motors and if not how could I control the speed of an AC motor? Thanks Great 'ible Alex Halford
Al1970 (author)  alexhalford6 years ago
Hi: Speed control for some A.C. motors is done by clipping the peaks of the AC waveform. But there are many types of A.C. motors and they don't all work the same way.
dchall86 years ago
Oh, yeah! That's what I'm talking about!! Here's a question for you. Can you do something similar to control the motors on an RC airplane or car with a wireless X-Box or Playstation controller?
Al1970 (author)  dchall86 years ago
Hi dchall8: I don't have a wireless X-Box or Playstation controller so I wouldn't know. I am sure they could NOT be used for an airplane, the range would be too short. The VEX transmitter was just so cheap on Ebay, I had to give it a try.
dchall8 Al19706 years ago
A power boost and antenna for a game controller seems like a worthwhile project for someone. The game controllers already have the joysticks, but they also have a lot of other buttons that could be used to do other things on the vehicle. For example if you had an aerial photography plane, you could pan, tilt, zoom, adjust the focus, etc. from one very inexpensive controller.
a wile ago i saw an rc car that was controlled by a playstation 2 controller but i dont know if you can still find one. i also saw a xbox controller (old one not new) controlling a rc heli (home made) wirelessly.
Very Cool! This will be very useful for a stage I building in the fall. Thanks Joe