The project:
Chasing undercarriage fluorescent lights.
Why it was done:
The reason for the lights themselves is quite simple. Ridiculous..ness. One expects to see these things on souped up little 4-bangers, not on a beaten up old 4runner.
The chasing aspect of the lights was, of course, because of my nerdiness. I needed a way to study for my upcoming midterm that was sure to force the concepts into my brain.
How it was done:
The credit for the lights themselves goes to my good friend Dan who designed the system. Rather than zip-typing neon lights to the car, as so many others have done, he decided that we should use fluorescent lights covered in colored acetate. We enclosed these lights in a metal bracket with hard, clear plastic below to shield the lights from debris on the road. These lights are all powered by four 12V ballasts hidden in a compartment in the back of the car.
As for the circuitry, I was in the middle of my second engineering class and had just learned about finite state machines. Naturally, I went to Fry's, bought a bunch of JK flip flops, and got to work (not knowing that the time that this was one of the silliest ways to do this).
The circuit has five states, one corresponding to no lights being on (achieved only at startup). Each of the other four states correspond to a respective single light being on. As the circuit runs, each new state is dependent on what the previous state was. That is, if light 1 is on in the current state, light 2 will be on in the next state, and so on, and the states advance with the signal given by the clock circuit. The circuit is also wired with "don't care" conditions. That is, if multiple lights ever turn on, only one will decide the outcome of the next state.
Each flip flop's output runs to a relay that controls its respective ballast, causing a light to turn on or off.
Unfortunately, I did not have a video camera at the time so I can't show you the lights in action, but trust me, it was cool. Here's a picture of my car next to Dan's:
It's illegal to drive with these on so they don't actually get used, but it's good to know they're there.
