[Ian Smith] sent us this POV display made from an old hard drive. It works by flashing some LEDs under the platter, which has a line cut in it. Since the platter spins at roughly 90 rotations per second, we perceive a solid image. He was inspired by [Alan Parekh]‘s project, but did several things differently. Mounting the LEDs was much simpler in this project as he had a strip of RGB LEDs that came with adhesive tape on the back. He also used a small magnet and a hall effect sensor to measure full rotations instead of an IR beam sensor. Check the video after the break.
As you can tell, its pretty loud. He says that he would like to enclose it with a plexiglass front to keep the noise down. You can get the schematics as well as lots of nice instructions from his site. He also make some recommendations of other projects to look at, such as another POV LED hard drive clock with a big touch screen.