This year the youngest child-unit participated in the Cub Scout’s Pinewood Derby. He did all the design, build, and paint work. He outsourced some of the electronics work to me.
The light is a BlinkM programmable LED. It was programmed (per the child-unit’s request) to blink like a police light.
The BlinkM light was powered off a 9v battery that was housed in the “bed” of the car. Because the BlinkM can only take a maximum of 5v a 7805CT (that was salvaged from an old TV set scanner) was used to regulate the 9v coming from the battery to a safe 5v.
While his car did not do very well in the races (5th place was the best he got in any of the heats) it was easily the coolest looking. And it was the only one that had working blinky lights!
Here is a video of the car racing (sorry for the shaky teenager-shot video):
Here are a couple of videos showing the light off. The BlinkMs are really quite bright (painful to look at directly):
And some pics (note that both the previous video and the following pictures were take after the car was used as a demolition derby car):