Tubular POV display

[Ryan]‘s cylinder POV display is an amazing piece of work. Right now it’s impressive sitting on his workbench, but we’re sure it would be astonishing hanging above the middle of a dance floor. There are 64 RGB LEDs on this display and they’re certainly bright enough to liven up any space.

Power is provided through a slip ring. The ground is connected to the shaft of the motor [Ryan] picked up at an auto parts store. It’s an efficient way to do things, but the display can only be controlled by whatever image is stored in the ATMega1284’s flash memory. [Ryan] admits this isn’t an ideal setup so he’s working on a ZigBee or Bluetooth connection.

We’ve seen some amazing spinny POV cylinders, but [Ryan]‘s build looks amazingly professional. All the board files, schematics and code are uploaded, as well as an image converter for BMPs and PNGs. Check out the demo after the break.

Comments

  1. Tom the Brat says:

    Like, totally tubular!

  2. _Taxx says:

    Wow, sounds like it’s driven by one of these: http://en.wikipedia.org/wiki/File:Renault70hp.JPG

  3. trollcookie says:

    Really nice … but, if the PIPA legislation gets passed, isnt your use of that goomba going to be a felony? And if SOPA gets passed, isnt this reason enough to shut down hackaday and youtube?

  4. Kevin Haw says:

    I’ve been playing around with cheap Bluetooth modules like these. They’re very simple to use with the Atmega. The real work would be the software to load the image, although it wouldn’t be too hard.

  5. Matt says:

    I noticed that when the light was turned off the spiral non-lit gap in the image narrowed. Does anyone know why that is?

    • Weaver says:

      A longer exposure time on the camera perhaps.

      • Kevin Haw says:

        OK, it’s been 30 years since my Photography merit badge, but… I think I figured out what you mean as I was posting a question on this. As a favor, could you take a second and review my logic, please?

        In normal lighting, the camera keeps a low exposure time automatically based on a sampling of inputs from the sensor. In less light it sets a longer exposure time for each line it captures, which means slightly more of the pattern is captured. If you had (and covered) a dedicated light sensor like on film cameras or were to set the camera to the equivalent of manual exposure mode, the gap would remain the same under all lighting conditions. But your image quality would suffer, being either dim in the dark or too bright in normal light.

        Hardly an urgent issue, but does this sound right?

  6. aafasfas says:

    You got a nice huge vibrator

  7. mess_maker says:

    It would be interesting to see how much electricity he could generate by having a static ring of magnets and a series of copper coils at the base ( and / or top ) of the rotating arm. The movement of the coil through the magnetic fields should generate electricity, but would it be enough to eliminate the need for the slip ring…

    My guess is that it wouldn’t be enough, though.

    • sk says:

      t would work but it’d be terribly wasteful.

      • Dax says:

        Dunno. A DIY axial generator is easily 60-70% efficient and he doesn’t really need all that much power, so it could be a solution.

        You can find suitable small neodymium magnets from an old CD-ROM drive, from the lens assembly. Then you need a pickup coil. You basically take copper wire and form a square wave out of it, and then wrap that around on itself in a circle, and sandwich it between pieces of plastic. It should look like a gear or a wheel with spokes, and the two ends of the wire is where you see the voltage.

        The magnets should be placed on a steel disc in a circle so that when the coil disc is placed on top, you get the magnets going north-south-north-south all around and matching the “spokes” of the coil. You don’t have to have a magnet for every radial lenght of wire, but you do have to alternate the order, because when you turn the disc, the current is going to run towards the center, or towards the rim depending on which way the magnetic pole is.

        So that’s a simple single phase generator. If you want more phases, simply make more pickup coil discs and stack them on top of each other, and then turn the disc to how many degrees of phase difference you want.

        If you have lots of magnets, you can arrange them into a Halbach array on the steel disc to direct the field further out through the pickup disc and improve the power and efficiency of it.

  8. Dave says:

    Here is a simple solution for the twisting of the device. Just grab one of those traction pads that you use in your car so your cell phone doesn’t slide around. Then stick the POV display on that.

  9. praetor says:

    I’m a machinist; as for the vibration you’re getting, something isn’t quite balanced; the motor isn’t quite centerd and perfectly vertical or the shaft the light array is resting on isn’t symetrical, or maybe even the frame. To remedy this you can balance the frame, motor or display unit with counter weights…or just simply get/glue 1/2″ to an inch rubber pads for the base

  10. Michael says:

    Has anyone else seen the giant versions of these they have on Sauchiehall Street in Glagow? They use them for advertising…

  11. Nagel says:

    What kind of rod/shaft is the board mounted to, and what kind of bearings are at each end of that? (I realize the necessity of a communicator, but what’s holding it together mechanically, not electically?) Very nice builld, congrats! I’ve done POV work for bicycles, and being more machinist than coder, I agree w “preator”‘s comments re: vibration. Bolt the sucker down, OR have a second display unit rotating in an opposite direction to cancel out the rotational resonance.

  12. its like a digital barber shop pole :D

  13. Keith says:

    I think you meant “commutator” not “communicator”. Nice work though!

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