Making a LED Spirograph with GlowDoodle



Sometimes all things for a cool experiment just show up at the right time. Not too long ago, Ryoko brought a book from Japan full of photos of objects in motion with very elegant traces of motion overlayed on them.
When Eric Rosenbaum visited from MIT a little later, and showed his GlowDoodle software again, it seemed like a perfect tool to make traces of spinning objects in real time.

Our first light spinner was a 16 inch wide disk on a lazy susan covered with black paper. A web cam was mounted about 2 feet above the center of the disk and the video feed was send to Glowdoodle on Eric's laptop. We spend the next hour watching LEDs make circles of light on the spinning disk, played with Mylar and glowing objects on the disk and then moved on to more complex motion. The traces in the video above were created by a LED light attached to a small battery powered fan with a popsicle stick and a lot of blue tape.


The fan motor moves the LED around in a circle and the flower patterns come about when you spin the big disk with the spinning LED on top of it. The patterns are similar to 1970s toy spirograph drawings (remember Spiromania? I wasn't born yet...), because a spirograph combines two circular motions in the same way: the small gear rotates around its center and moves around in a circle at the same time.

While we were still watching the fan and trying different speeds, Ryoko came back with a contraption including a motor, a cricket and a light on an extended arm. Her cricket controlled light rotator resulted in an LED moving somewhat randomly but also following a pattern. We placed that on the big disk and started spinning it slowly. Check out the video below, I think it looks a bit like graffiti:

We like the seemingly chaotic motion which turns into a pattern after a while, of course the sound is a great addition too!

I hope to set up a more sturdy and bigger turntable with a screen next to it for a while and invite friends and visitors to come up with different moving light contraptions to place on it. It's pretty mesmerizing to watch the patterns appear and become more and more dense until the screen is filled with a web of white lines showing the path of the LED on it's way round and round. Perhaps we can even use our existing turntable exhibit or pulley table exhibit as a platform for a light spirograph setup on the explOratorium floor once in a while…

Great post! Some ideas for future explorations come to mind... You could use the "darkpainting" version of glowdoodle with all-white rotating discs and colored dots to leave a trail (so no battery powered lights would be required). You've got second-order rotation (something spinning on top of something spinning), so how to get third-order? It should be doable with a sturdier mechanical design...

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