Introduction: Pinewood Derby Car With LEDs and Jimmy Neutron

About: Founder of Powerhouse Electronics. For more info goto:

You know your in trouble when you start worrying about the software in your son's Pinewood Derby car!

This year I decided to give up trying to compete with the "Gear-Heads" in our Cub Scout Pack. There are just too many variables when trying to build a fast car. However, the Gear-Heads always seem to get lucky.

The first year we built a really fast car - I think it was just dumb luck. We placed second overall for speed that first year. That was out of a pack of 50 cars! There is nothing better than winning.

We'll, with a little taste of success under our belts, we thought we could simple do it again. Wrong! I pulled all the tricks last year and put a ton of time into trying to build the ultimate speeder. The reward for all that work was a car that finished in the bottom third of the pack for speed. Bummer! There is nothing worst than losing.

OK, this year is going to be different. To heck with speed. If we can't build a fast car then maybe we can build one to win all the style points. Eight and ten year old boys really go for the styling. A cool car can be even better than a fast car - at least that is what we're telling ourselves. So, what will little boys go for? The Gear-Heads also come up with stylized cars too. What can we EE's do to win style points? Bingo! Lets add some blinky lights to our car! No way the Gear-Heads can keep up with that.

And so the Jimmy Neutron LED Pinewood Derby car was born. There, take that, you Gear-Heads.

Step 1: Jimmy Gets Hacked.

Have a look at the images below.

Step 2: More Build Pictures.

See more pics.

Step 3: Software

The PWM software that does the magic is running on a single Kemper LED board. Instead of using the standard firmware that comes with the board I replaced it with some custom code. The custom code just simply makes all the LEDs come to life automatically right after power is applied.

Attached is all the source code needed to reproduce the LEDs.

If I had more time I would have built some delays into the code. Instead, the LEDs just ramp on & off at different rates. It would not take too much more effort to add those delays between each pulse.

We also made our own stickers this year with Inkscape. Here is a tip, spray some clear-coat over the stickers before you start cutting them out. The sticker tend to smear with oily fingers. Still, the stickers didn't turn out too bad.

I hope this helps inspire my fellow EEs who want to show the gear-heads a thing, or two,

PS: As always, I'll port some more detailed info on my web site. Have a look at for more info.