"Acid Machine Synth: This DIY machine allows you to visualize the sound using a rotating disc printed with a special pattern that displays the note being played. It works by making an "LED blink in the frequency of the sound, and rotating the image at a set speed."

http://www.youtube.com/v/wZSA1BXte_g

http://gizmodo.com/5...otizes-two-ways

Whoa cool, but I was expecting it to be a bit more extravagant. Still cool though. I wonder if there are any schematics for it on the internet.