Instructables
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?

EDIT #2: (5/28/13) I recently made another project and Instructable very similar to this one. I mounted an Airsoft machine gun on the top of an RC car! Here's the link to see a full video tutorial to make it: http://www.instructables.com/id/Airsoft-Gun-on-an-RC-Car-Hack/

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lukeD8 hours ago

THANK YOU A LOT!
In my case I am going to mod my rc boat, im planning to make a feeding boat for carp fishing. The third channel will be used to flip a box or someting (filled with food for carp fishing, to say it simply) so al the stuff in it will fall out of it. That way I'll be able to feed the carp on just the right spot (wich isn't the case if you throw it by hand).

Nice and clearly Idle!

Itchyzombie5 months ago
I'm a 12 year old and I'm proud to say, I did it. :)

if you need help search up the ic on your car, my New Bright was different so thats what I did.

I put a breadboard on top of the hull instead, for my arduino and stuff.
gunman157 months ago
I am going to have to do this, do you know of a way to attach a live feed cam to it also.
cplnerf1 year ago
is there any cheap way to send live video feed through? Do you know of any app and cheap camera pair that will work over bluetooth on an iPhone?
Is the third channel analogue like the other two? Can you choose the strength of the water?
ldrago8081 year ago
Where does the other end of the battery connect to?
Great way to build a RC north korean nuke launcher truck!
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.
just wire the gun up to one of the drive motors, make sure you know what your are doing though
tman271 year ago
That is f@&&!/&! Awesome
robo103021 year ago
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:)
katman1011 year ago
i love you in the least weirdist way possible
ivanjacob2 years ago
are you selling them?
Brian Henderson (author)  ivanjacob2 years ago
I've thought about it - the whole project takes like 15 minutes at most :D
its taken me forever
cplnerf2 years ago
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
Brian Henderson (author)  cplnerf1 year ago
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.
i have the exact same car and chip set though the only difference is i got mine last year
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.
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
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.
it would be beast! if you combined this with your rc camera car!!
Brian Henderson (author) 2 years ago
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
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
Find a Fully Automatic Nerf Gun, and name the resultant project F.A.N.G...
Brian Henderson (author)  karlpinturr2 years ago
Yes please! F.A.N.G. is so much better than what I came up with :)
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.
Sounds like a fun idea.
cplnerf2 years ago
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
Eddie42 years ago
this is a really cool project
if stores sold it as a kit they would make alot of money
Nicbur2 years ago
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.
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
Gydoko2 years ago
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...
Elmardus2 years ago
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.
Brian Henderson (author)  Elmardus2 years ago
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.
Thank you for the tutorial. Really appreciate!
aertemis2 years ago
thats sooo CUTE...
darthbean182 years ago
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?
Brian Henderson (author)  darthbean182 years ago
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.
edc73937.jpg
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).
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