Gareth Branwyn, who authored the beambot article in Make issue 6, wrote up a cool article about Zach DeBord’s twin-engine solarroller. This thing is a beambot hotrod!
Zach on building BEAM Roller circuits: “I usually build engines in a batch for later use. In the image below, you can see that there are sockets on top of the engine circuits (made from IC socket pins). These are used to easily plug in the solar cells. The two leads (red and black) coming out of the back of the engines go to the motors. In this picture you can see the two types of engines that I make: one “classic” configuration with storage capacitors (the two engines on the left) and another config using Polyacene disk batteries in place of the caps (which deliver roughly .6 Farads of stored power). These are represented by the three engines on the right.” - Link
You can find Zach’s flickr set here.