A small, light-seeking robot my son and I soldered together. Got it from the local electronics store for $20. It has two light-sensing 'eyes', that will 'steer' it via the two motors to the brightest light source. The LED's light up to show you which direction it's headed. Stick a flashlight in front of it in a dark room, and it shoots right for it.
See more pics of it:
http://www.flickr.com/photos/8064698@N03/sets/72157603704661570/
No, it wil bonk into things, but if they're in the shadow it does a pretty good job of turning around and heading back towards the bright spots.
warpcat 7 months ago