The project:
A grill-mounted light sweeper: a string of light bulbs that chase back and forth as on KITT's grille in the TV show, Knight Rider.
Why it was done:
Growing up, I watched a whole lot of TV. One of my favorite shows was Knight Rider starring David Hasselhoff as a crimefighter with a supercar buddy, KITT. KITT was an indestructible 1983 Trans Am loaded with all kinds of intelligence and neat gadgets. Its most prominent feature was the red light scanner above the front bumper that would constantly sweep back and forth throughout the show.
Well instead of studying for the final in my second engineering class the way most people did, I decided to put my newly found knowledge to use by attempting to find an ’83 Trans Am and building a light scanner for it similar to the one in the show. As luck would have it, my good friend Jericho happened to own a mint condition black 1983 Trans Am (read: beat up, barely running tan 1985 Ford LTD). He kindly donated his car to the cause and I was on my way to achieving an unparalleled level of nerdiness.
How it was done:
A clock signal is given by a 555 timer. The output is connected to the clock input of a JK-type flip flop (both data inputs high) to create a half-clock signal.
This half-clock signal is inputted into an 8-bit binary counter. The lower three bits of the binary counter all connect to the inputs of two 3-8 binary decoders. The next significant bit is then used as a chip select for the two decoders (the signal is inverted for one of the decoders).
The binary counter has a direction pin (count up or count down). This is controlled by a flip-flop that is set and reset by the first and last of the output pins. This flip-flop is on the original clock signal (twice the speed of the binary counter’s) to allow it to update before the counter attempts to increment.
The circuit itself is in a hacked project box from Radio Shack. Three holes were drilled into the box: one to hold the potentiometer knob (speed control), one for the on/off switch, and one for the power/ground wires (which come through a fuse directly from the battery). Two squares were also cut out for RJ-45 connectors.
The front grill has sixteen 12 volt light bulbs, each with its own NPN power transistor. One terminal of each light bulb is connected directly to the battery’s positive terminal while the other is connected to the collector of the NPN transistor. On the emitter is a resistor connected to ground. At each base is a resistor which connects to a pin on one of two RJ-45 connectors. A pair of network cables runs from the grille to the project box inside the car’s center console.
The result:
Here is the video of the project in its different stages:
