My little boy wanted me to enter the 'grown up' category of his Cub Scouts Pinewood derby this year... this is what we came up with.
Its a police car with 6 LED's (2x clear headlights, 2x red tail lights, 1x red & 1x blue for the siren), a 3 axis accelerometer to detect movement and a piezo speaker for the sound effects. It's all controlled by an Arduino Pro Mini.
It was an easy project and a HUGE hit at the race. However... If i where to do it again i would not add the speaker or the accelerometer. The race was too noisy to hear the speaker and with all the kids bumping into the track the car always detected movement (the lights where always on).
If i where to do it again i would not add the speaker or the accelerometer. The race was too noisy to hear the speaker and with all the kids bumping into the track the car always detected movement (the lights where always on).
Pah! Just a little filtering should be able to discriminate vigorous shaking from random kid bumps. Try integrating/summing the squared accelerometer signal over a half second or so. It should be much more energetic with vigorous shaking.
This year I used a Funnel IO and xbee to trigger my PWD lighting. I had thought about using an accelerometer, but for the exact reason you mentioned, I didn't. I wanted to have the control when I needed it.
For next year... Some of the other leaders and I have been talking about the idea of entering some cars which would strictly race against themselves. We would throw them in the line up now and then and have something outrageous happen. We were thinking about...
Cars held together -w- electro magnetics which would blow up on command (actually many of the ideas involved some sort of blowing something up). We thought about using a couple of servos so a new part of the car could be revealed just before the race. Hows about a car with a inverted mouse trap. Then use a solenoid to release it sending the car into the sky. It's all fun and games until someone pokes their eye out.
Another line of thought would be to use the track as a conductor (assuming metal track). Then all sorts of things are possible. And really at that point, you do not need to worry about on/off because the track would close the circuit.
Glad to see other geek dads making something that the kids will really dig. It is those kinds of things that I remember from my childhood.
The light bar is just thin plastic sanded to make it 'frosty'. I then just folded it into a box. I don't remember the thickness... but i use tons of the stuff to make canopies for my R/C Planes.
I think next year I'm leaning towards a Fire Truck. When the car hits the bottom of the hill (start of the flat part) it would extend the ladder out in front of the car. Basically adding a few extra inches to the length of the car, thus crossing the finish line faster
a small servo t hat will unfold wings in the middle of the run, just enough to give it lift and 'release it' from its mortal coil.
servo controlled valve, to co2 canister, NOS! baby!
combine the two for epic lolz
i always wanted to try a spring loaded hidden car in the derb. Something that shoots out and triggers the end of track system (impact or pass through light ... what'ev.
Dad and i stopped competing with the rest of the guys cause we always wanted to stretch the limits.
