Today at the Children’s Museum, I worked with Paul to prototype a workshop activity that I will be running there with Hack Pittsburgh in the near future. After a few failed attempts while we worked out the right combination of materials and sizes, everyone was able to build a motor that worked at least part of the time.
This is almost the simplest motor that you can make, all you need is a AA battery, a couple of paper clips, ~18″ of 26 awg wire, a magnet, and some tape. The only tricky bit is that you only file off the enamel on half of one of the sides (radially), so that the coil is only energized during half of the rotation. Basically, the coil is heavier on one side than the other, so the force of gravity causes it to spin towards that orientation. When the heavy side is at the bottom, it starts to conduct electricity, which turns the electromagnet on. The electromagnetic force from the coil is then repelled by the fixed magnet, which causes to the coil to flip over. But then, the coil is resting on the insulated portion of the wire, and gravity takes over again. If you line everything up just so, and give it a little nudge, this unstable system will cause the whole unit to spin around.
As usual, there was lots of awesome stuff going on at the museum, including an animation station where kids could make a stop-motion video using an overhead camera and scraps from the crafting area. When I went over to check it out, there were two girls making an animation about a bear that ate a poisonous mushroom and floated up into the sky to eat the sun. Absolutely wonderful and ridiculous, I wanted to make one! As a bonus, the videos are going to be screened in the downstairs theater. I totally want to steal their idea and go make my own animations now