A few weeks ago, I found one of these bad boys lying on a table marked “free.” Compulsive hoarder that I am, I picked it up and immediately thought of what awesomeness I could convert it to. I settled on controlling an RC-car with it because I had a car handy, and I thought it would be cool to take this approach to driving it. Originally, I was controlling the whole thing with an Arduino, but it turned out to be kind of a waste of a 50-dollar microcontroller, and I didn’t want to have Arduino stuck in this project forever. So I got to work on doing everything with hard logic. First, I unplugged and removed the board from the steering wheel base to simplify everything before I even got started. Ignore the wires sticking out of it.
Next, I got to work on the board. I had discovered, back when I was controlling it with an Arduino, that in order to activate each function (Forward, Back, Left, Right,) I had to ground one side of each button-pad. Comparators seemed like the best way to do this, so I decided to use a couple of 358 opamps as comparators to take inputs from the pedals and such and compare them to a set voltage, and flip to negative if the pedals were pushed down or the wheel was turned a certain way. Here’s a schematic of the circuit I built: Sorry if it’s confusing. I’m kind of new to this.After a few hours of soldering and such, I had this:
I used potentiometers to create reference voltages for the steering wheel. This way, when supply voltage changes, it doesn’t throw everything off. This is also pretty handy because I can change how sensitive the steering wheel is in about 14 seconds flat.