2013 Pinewood Derby
This year the youngest Child-Unit did the Cub Scout’s Pinewood derby again. Like last year he designed the car and I helped him with the electronics.
The fading LED was done by using a 555 timer. I believe this schematic is close to what we used. The only real difference is that R1 in that schematic was replaced by a trimmer pot so that the fade speed could be adjusted.
Power was provided by 3 CR2032 batteries connected in series for a total of 9 volts. The dome was just a scrap piece of plastic, with two metal pieces from a hard drive glued to the ends.
Unfortunately, this was one of the slowest cars at the race with a top speed of ~5.8 MPH.