Hack an RC car's unused 3rd channel!

So, as we all know most remote control (RC) cars use only 2 channels on their remote control: one for forward and backward, another for left and right. What you may not know is that there is an unused third channel on most RC cars! Cheap cars such as the New Bright line found at places like WalMart and Target use a standard chipset (RX-2/TX-2) found in many many remote control vehicles.  Today we will be hacking that third, unused channel.  On the RX-2/TX-2 datasheet, that third channel is called the "Turbo Mode".

This Instructable showcases a couple of example projects I made to test out if I could take advantage of this unused "Turbo Mode" and operate a gun turret remotely. I built two vehicles - one using a fully automatic battery powered Nerf gun and another using a battery powered squirt gun with an electric pump.

EDIT: I originally titled this "Hack an RC car's unused 5th channel!" but I've since been informed that it's actually just three channels.  The forward/backward and left/right controls are just two channels!  If you see me refer to a 5th channel, just imagine I said three, okay?

Helpful Guides:

• I was helped greatly by this Instructable by techbitar: "Use Arduino with TIP120 transistor to control motors and high power devices"
• I also found some great information from this tutorial: "Using a transistor to control high current loads with an Arduino"

Step 1: Supplies List

I was amazed to find that between your local Walmart, Target, and RadioShack one can find all the parts necessary for this project!  In fact, this project is so quick and easy that you can do it in mere minutes if you know what you're doing.

You will need:

From Target, WalMart, Toys 'R Us, or wherever:

• RC car - try to get one big and powerful enough to carry a couple of extra pounds on its back. I used this H3 Hummer from Target.  It was on sale!
• Battery operated Nerf gun, squirt gun, or anything else with a little DC motor in it you want to trigger remotely. I managed to snag this beauty (the Nerf Swarmfire) on sale as well for just $15!  I also found this gun (the Super Soaker Thunder Storm) for $15 as well.

From RadioShack:

• TIP120 transistor  Catalog #: 276-2068
• 1N4004 diode Catalog #: 276-1103
• 1kOhm resistor Catalog #: 271-1321
• While you're at it, you might as well get a bigger capacity battery because we KNOW the one that comes with whatever cheap RC car you're using ain't going to last.  I used this one - Catalog #: 23-1272
• I found these battery connector clips useful too - Catalog #: 23-444
• Some sort of extra button or switch to put into your remote control

Comments

[tman27]

That is f@&&!/&! Awesome

[gravityisweak]

So the TX-2 Turbo chip is in the remote. The RX2 chip is in the car, is that correct? Let's say I don't care about the car moving forward or backward anymore, and just wanted to make a stationary mounted nerf gun that I could remote control to shoot at people walking up my driveway. Would it make the project any simpler? I'm pretty interested in figuring out how to use cheap remote control car guts as on/off switches for random objects.

[robo10302]

Hello,can you please help me?on the receiver the IC is the same(RX-2B) But on the transmitter my IC is (TX-2E),will you please give me some suggestions on schematic of this IC?Its a different car:)

[katman101]

i love you in the least weirdist way possible

[ivanjacob]

are you selling them?

[joedog86]

I've thought about it - the whole project takes like 15 minutes at most :D

[cplnerf]

its taken me forever

[cplnerf]

PLEASE HELP
i am using the same rc hummer but i got it last year. The circuit board is almost idenical to the picture. the problem is the led on the remote just remote just stays on continuously. there are no wrong connections on the remote. i used the 6th pin from the top on the left connected to a switch that is connected to the ground or negative terminal. its the right negative terminal too. when i press right it goes right/back and left = left/back forward rarely works and the gun does not work either. my remote led will act normal but it goes back to troubled after a minute.(it could be because of slight shaking) i am using 6 recharged AA batterys each outputting 1.2 volts adding up to 7.2 volts and the same with the 6 volt rechargeable battery
PLEASE HELP

[joedog86]

If you disconnect the switch you put in, does it fix the problem? Sounds like you hooked it up right. Another possibility - the pin that the gun assembly is connected to might be different from the one I used. Do you know how to use a voltmeter? You might try pressing each direction on the remote control and seeing which pin gets voltage with each direction.

[cplnerf]

i have the exact same car and chip set though the only difference is i got mine last year

[cplnerf]

thank you so much but the remote works out of randomness now that i took the button out but it turns out the turbo pin on the remote was completely desoldered when it took it out but the remote did work at times and the led that indicated a signal going out did go on.
now i have to use another remote.
i will try using a multimeter.
do you have any tips on soldering the tiny pins?, i have a regular solderer and a pencil tip (?) (thin tip?) solderer.

[Ilija Miljkovac]

do you mind if i take this idea and ann something like a live action camera+something to control it from a computer?And if yes do you know what that can be

[joedog86]

It's not controlled with a computer but I made something kind of like that. Here's the video I made a while back: RC Drone video

I'm currently working on a pan tilt assembly controlled by a Wii nunchuk controller and an Arduino. I need to get an XBee radio or something similar to make it all wireless.  I might as well turn it into a full blown robot at this point though and let the Arduino drive the car while I'm operating the camera/turret assembly.

[cplnerf]

it would be beast! if you combined this with your rc camera car!!

[joedog86]

Hmm, this fully automatic Airsoft gun for $20 at Walmart looks promising...  

http://www.walmart.com/ip/Crosman-AS-Pulse-M74-Dual-Power-Mini/13916909

[cplnerf]

PLEASE HELP
i am using the same rc hummer but i got it last year. The circuit board is almost idenical to the picture. the problem is the led on the remote just remote just stays on continuously. there are no wrong connections on the remote. i used the 6th pin from the top on the left connected to a switch that is connected to the ground or negative terminal. its the right negative terminal too. when i press right it goes right/back and left = left/back forward rarely works and the gun does not work either. my remote led will act normal but it goes back to troubled after a minute.(it could be because of slight shaking) i am using 6 recharged AA batterys each outputting 1.2 volts adding up to 7.2 volts and the same with the 6 volt rechargeable battery
PLEASE HELP

[karlpinturr]

Find a Fully Automatic Nerf Gun, and name the resultant project F.A.N.G...

[joedog86]

Yes please! F.A.N.G. is so much better than what I came up with :)

[pack77wood]

hey you and the dude who made the nerf tank should get together you could have a ramp on his tank for the ankle biter or fang so if the nerf tank battery dies FANG is there to protect it all you have to do is just drive it down the ramp.

[freeza36]

Sounds like a fun idea.

[cplnerf]

PLEASE HELP
i am using the same rc hummer but i got it last year. The circuit board is almost idenical to the picture. the problem is the led on the remote just remote just stays on continuously. there are no wrong connections on the remote. i used the 6th pin from the top on the left connected to a switch that is connected to the ground or negative terminal. its the right negative terminal too. when i press right it goes right/back and left = left/back forward rarely works and the gun does not work either. my remote led will act normal but it goes back to troubled after a minute.(it could be because of slight shaking) i am using 6 recharged AA batterys each outputting 1.2 volts adding up to 7.2 volts and the same with the 6 volt rechargeable battery
PLEASE HELP

[Eddie4]

this is a really cool project
if stores sold it as a kit they would make alot of money

[Nicbur]

Sorry, I know this comment is a little behind. I was trying to do the same thing with an air-soft gun and ran into a problem that when I turn it on I can steer and use the car fine but once I fire the gun and then try to move forward/ steer the gun triggers even though I didn't hit that switch and as it tries to move the gun uses all the power so it just lurches about 1/4 of an inch. I'm using a car that used to be able to transform and replaced that motor with that of the guns. The only difference is, it lacks a small green circle that was attached to both ends that said 473 on it. I was wondering if you could help solve my problem or tell me what that is?
Thanks a lot, Nic.

[Ihackedyouraccount]

Hey there is a circuit diagram app for the iPad. Although it will cost you $10 it's worth it I love it I think it's called I circuit

[Gydoko]

Thank you for posting this! i learned much of it (of 3 channels instead of 5, and i watched an old remote, and its 6th pin wasn't connected to something...
im gonna try something...

[Elmardus]

Nice tutorial, but that about the 5 channels is not correct. Over time I have become something like a RC expert, and I noticed this:
There are only 2 channels normally used. Backward AND forward is one channel, and left and right is ONE channel. It is just the motor moving the other direction, but on the same channel.

So it has 3 channels, one unused, and not 5.

[joedog86]

An important distinction! Thank you for the information. This is why I love Instructables. Looking again at the datasheet I found, it does indeed only say the following:

"The RX2D has five control keys for controlling the motions (i.e.
forward, backward, leftward, rightward and the turbo function) of the
remote controlled car. It can be used together with TX2B."

Note that it says that the chip has "five control keys", NOT five channels. I've seen the TX2/RX2 referenced as a five channel chip set in various places around the web, but perhaps that's a misconception on others' part.

[bowlofnoodle]

Thank you for the tutorial. Really appreciate!

[aertemis]

thats sooo CUTE...

[darthbean18]

Thanks for the 'ible! I'm trying to work through it with a very similar car, and I'm wondering how you hooked up the 'fire' button?

[joedog86]

No problem - I whipped up another drawing that I'll add to the Instructable. Paper for iPad is quickly becoming my new MS Paint for diagrams :)

It's a simple circuit - just put a switch or button between pin 6 of the TX-2 chip and ground. If you don't know where to find ground, just use the negative battery terminal of your remote control. Pretty safe bet.

[spystealth1]

You might want to add something in your instructable about SMD chips. I took apart a fairly large car a while back with this chip, but to save money the companies who make them will often use the SMD version of the chip (at least in the car). It was tricky with my dull,cheapo radioshack soldering iron I had at the time, but I managed to solder a small wire to the turbo pin. A lot of people will probably get the smd version, especially on the tiny cars (which could make some pretty cool projects themselves).

[Dominion-Network]

Damn you, I was going to do an instructable on this as well, but I take my hat off to you sir! a very nice instructable

[spystealth1]

Aaah! Same here! I had a bunch of these lying around and so I took them apart and looked up the datasheet. I noticed the turbo pin and hooked things up to it and added a button on my remote, but I guess it never made it past the prototyping and tinkering level. Never thought to make an instructable on this. Great job!

[joedog86]

That's ironic because it was your Tyco RC Arduino Robot Instructable that gave me the itch to play around with hacking RC cars! Nice to meet you!

[Dominion-Network]

I'm glad I inspired you, I'm currently working on an instructable that uses the Air Rebounds controller and receiver board that came off the car as a 5 channel remote trigger for airsoft stuff.

[joedog86]

Sweet! Hacking's no fun unless you can take perfectly safe toys and turn them into remote controlled weapons :D I really want to make a remote controlled water gun or Airsoft turret, but I haven't found a design for the platform and gears that I like yet.

[Dominion-Network]

I've featured your instructable on my site, with an article about it, check it out here and please give some feedback :D

http://dominion-network.co.uk/2012/04/14/when-inspiration-strikes/

[Dominion-Network]

So far I've gotten the normal 4 channels working perfectly, now with your help (As I said you beat me to it) I can add the 5th channel to the controller.

[robotmaker]

looks good,i get mine from thrift stores for $3- $7
but i turn mine into robots with camera,or palm pilot or computer controlled
fairly easy to do