I picked up a small RC car, about the size of a matchbox, today and have decided to reverse-engineer it in order to have my Raspi control the car remotely. The idea is to use Pygame or some other python library program to control the car via the GPIO pins.
It’s a pretty simple controller. I choose the car for its simplicity since unlike most RC controllers; this one’s controls are simply on/off push buttons. Most of the time RC Car manufacturers use analog potentiometers in order to give the user speed control as well, but this 10€ model only allows the user to determine if it goes forward/backward, no control of how fast. That makes it much easier to control, since we can replace the pushbuttons with transistor logic.
After taking the controller apart, I establish that all 4 (left, right, forward, backward) pushbuttons result in voltage going from 0 to just over 3V, with very little current on closed position. This is great, since we can power the whole controller from the 3,3V pin on the Raspi (I decided the voltage was within tolerances so did not need to be stepped down.)