Slick 16-segment POV Hard Drive Clock


Hackaday reader [svofski] sent in a fantastic looking hard drive-based POV clock (Google Translation) created by a maker in the Sichuan province of China. The clock, like the one [svofski] built, relies on LEDs placed behind the spinning platter to create the POV effect.

Quite a few carefully placed cuts have been made to the platter, which make up the segments required to display both numbers and letters of the alphabet. This isn’t a simple 16-segment POV display however. The font uses a lot of sharp edges and odd segment lengths, so we’re guessing that quite a bit of care was taken in the production of this clock.

You can see a demonstration of the clock in the video embedded below, which shows off its ability to display numbers, text, as well as a handful of simple patterns. It looks like there are some details available on the designer’s site, however it is all in Chinese, and Google’s translation is questionable at best. If only we knew someone that could give us a hand with deciphering the inner-workings of this clock…


20 thoughts on “Slick 16-segment POV Hard Drive Clock

  1. I you look at alphanumeric segment display, you can count 16 segments. But this one add some extra segments some make it seamless.
    The question is how the lights are placed behind the platter.

  2. Get 16 arduinos, all of them with the ability to sense when the 0 is on top. Time the revolution time and do simple arithmetic to predict when the digit will pass above the led on your output to flash it.
    Now stuff the function of 16 arduinos into 1 arduino.

  3. Now that the idiots at the US government have decided they can take down ANY .com and .net domain it must be a bit odd that baidu is, I guess the US government is by extensions also responsible for the censorship the baidu searchengine employs too then? ouch.

    On the subject of the video itself, yeah those cuts have a mystic quality, and you only see a short glimpse of them to add to the mysticism.
    But realistically it’s not all THAT hard to figure out surely, it’s just a matter of timing

    I wonder how the cuts were made, CNC or laser or by hand or maybe even etching.

  4. It’s gorgeous and unusual. Thanks, hackaday!

    You don’t need a translation. You can just use your big brain to figure it out, but I’ll lend you mine for a while.

    The picture you need is at 2:24 in the video, which shows you the cuts that are used for the segments and the big semicircular cut that allows the processor to sense the position of the disk.

    Underneath the hard disk with the slots and cuts
    are 16 LEDs, with diffusers in front of them. They are arrayed around the central shaft, in 22.5 degree sectors.

    After that it’s all denouncement. When the segment that you want comes over the digit position/led position that you want, you fire the LED. You use an infrared LED retroreflection sensor to sense the edge of the inner semicircular slot, and use that to keep your
    LED timing straight.

    If you put 2 more LEDs in each diffuser box, you
    could have it do full color. With more careful
    timing, you could make the text crawl continuously around the edge. You could cut polygonal pixels into the disk, instead of strokes…


  5. I’m with Nathan, there’s 16 cuts, and I bet they’re all blocked off and the back side of the disk painted matte black. The center ring cutout is probably for speed sensing/control.

    The logo on the DIP40 sure looks like an Atmel, probably an AT89S52 (32 IO pins). The smaller IC is probably the TDA5140A he mentions in his blog. There’s also a better close-up of the disk on his blog, as well.

    Looks awesome, I want to build one!

  6. For Strobeshnik I used electro-etching, but it’s a very time-consuming and painful process. The cuts like in this clock, unless you have a factory handy, are best done with a dremel milling bit and perhaps an old fashioned file. It’s a matter of proper markings, then it should be really easy-peasy.

    The leds are located under the disc, number of segments in digits = number of sectors in disc = number of led groups. Really simple and cool. I wish I have thought of that :)

  7. I agree that he used that half-circle slot to sense position.

    But don’t hard drives already have a stepper motor or a way to sense position? Or do they just read whole tracks and unravel it from there?

  8. my jaw is dropped

    I was about to consider submitting my own HDD clock but it was just a simple linear hand type.

    throughout the build I really wanted to make something with more finesse along the lines of this but I couldn’t think of how I would go about doing it without needing all of the separate LED boxes like this person has done.

    truly impressive in all aspects of the build!

  9. Anyone else reminded of the Baird disc-type ‘televisor’ TV? Replace the slot cuts with a spiral pattern of dots (a Nipkow disc), and you can display arbitrary images as long as you can pulse your illuminator fast enough.

  10. In typical Baird TV your picture is limited to a small sector. On a second thought, if you make e.g. 16 holes and make 16 independent sectors like in this clock, you’ll have a 16-line circular raster. Nice idea worth trying, no? :)

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.