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: https://www.instructables.com/id/Airsoft-Gun-on-an-RC-Car-Hack/