LED POV Hard Drive Clock

[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.

29 thoughts on “LED POV Hard Drive Clock

  1. Awesome! I think I might try this with an old CD-ROM drive since they have an easily controlled brush motor and I could etch off the top layer of a CD more finely than I could cut a notch in an aluminum platter.

  2. Wow this has got to be the neatest hard drive project I have seen. Also the most impressive looking. I will view the instructions and see if it is something I may be able to replicate.

  3. I bet some of the low-frequency hum could be eliminated if he could rebalance the platter. The slit makes that side lighter, and then he makes the other side even heavier by gluing a magnet to it.

  4. I saw this project and really liked it and decided I wanted to try it with a laptop HD… unfortunately every method I’ve tried (the grinding tools and various cutting tools) with the dremel break or shatter parts of the platter.

    I suppose the larger drives have sturdier platters. Has anyone tried cutting through a laptop drive platter before?

  5. That is awesome.

    And that 2.5″ platter is glass? At least that is what I hear.

    Try a 1.8″ HDD next :P, or go the other way and make a huge one out of something different, like maybe a car wheel with a full hubcap, and a line cut out of it :). Or a CD painted black maybe.

  6. Reezy, that would be awesome, have 2 or three of these doing visualizations, better yet mount it as part of a projector lens (like some auxiliary car lamps), then it would be a really neat graphic display for music.

  7. @davi,

    Many hard drive platters made in the last 10 years or so are glass, not aluminum. Glass is a more stable material than aluminum.

    All you need for the “slit” on a glass platter is to remove a stripe of the magnetic coating, which you could probably do with a carbide tipped scraper and a straightedge. You’d have to scrape both top and bottom of the platter, of course.

    This is an awesome project, and I’m seriously thinking of making one. God knows I have enough crappy old hard drives!

  8. Pretty nicely done, but as he says himself you do want to put it in some soundmuffling enclosure, I’d go for glass I think, not sure acrylic will block much, plus it’s sensitive to scratches.

    As for the clock ‘running backwards’ that would probably be an optical illusion caused by the refresh frequency of the camera I imagine.

  9. You have to find hdds with a low capacity, the higher the capacity the higher the chance to get glass platters.

    But with glass platters you have the chance to make the slit without changing the balance. (Maybe etching would be a possibility…)

    As for the sync signal, you probably can use the tachometer signal from the drives motor.

  10. I wish I could bump this, but I wanted to say that Jaded is absolutely right about platters, especially smaller capacity ones being made of glass with a magnetic coating on top.

    I’ve played around with the attachments I have for my dremel, but I’m hard-pressed to find something that can scrape off a clean line. Any ideas?

  11. What about some PCB etching solution, or a related chemical etch to remove the stripe. A little contact paper to mask the area around it..

    Or failing that, make one edge straight on top, make the other edge of your ‘slot’ straight on the bottom. The light shining through doesn’t care if there is a ragged edge opposing the straight one on the top or the bottom, as the magnetic material on the other side of the platter would mask it.
    That would make it easier to just lay a straight edge on the platter and clean some of the material away with an x-acto or the like, then flip, repeat.

  12. @Melvin: that was exactly what I thought, but you still need an index signal, because you not only need to know the speed but also the position of the disc.

    Balancing the disc after cutting the slot shouldn’t be all that hard, just hang it on a smooth rod, spin it, and if it stops repeatedly in the same position, or rocks back and forth just before it stops, remove some material on the bottom side, and try again. This is basically how many mechanics still balance motorcycle wheels.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.