Step 1: Overview
This instructable shows how to hack up an R/C car and connect it to your computer. I made a web interface for mine so that my mom could drive a little car around my room from north carolina (I'm in boston), using a webcam to watch it.
This is pretty fun project, takes about an hour to solder up, and if you can make toys computer controlled, you'll uh.....have lots of friends
Also, I'm writing an instructable on using an R/C car to make a digital radio link. Stay tuned, amigos.
Step 2: Get the parts together
an old R/C car and its transmitter--this current version might work for transmitters with digital proportional control, but it's designed for transmitters that just have on/off buttons
a proto board--I really like the radio shack PCB boards that are basically breadboards, except pcbs.
an atmega48--smaller processors will work, too, but I have tons of these around, they cost $1.65, and the code I wrote is guaranteed to work for them
a max232 chip (or a max233, if you're rich, lazy, and classy)
a female DB9 connector (with soldertails)
4 1uF capacitors(for the max232 chip)
a 7805 voltage regulator
as many 2N2222 transistors as you have buttons on your transmitter (I had 6)
a 1K resistor for each transistor