Microcontrollers are great at blinking LEDs and reading sensors. With that in mind, I built this simple electronic finish line so that my 5 year-old son could easily see which of his hot wheels finished first.
Note: I've found some improvements since I wrote this: use an IR emitter/detector pair with a higher resistance on the detector (330K ohms instead of 56K ohms). Also, A "mini" arduino should work just fine -- the adafruit.com "Trinket" for example.Features:
- First place displayed
- Ties displayed
- Automatic reset
- Easy operation and reading
- 20 microsecond accuracy
With some basic soldering skills and woodworking skills, you should be able to complete this build in only a few evenings.