POV Display with an Element of Danger

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Persistence of vision displays are always cool, although we must admit this one looks like it could very well explode at high speeds…

Safety concerns aside, this desk fan based display provides a great starting point for learning about making POV displays. It makes use of an old cellphone battery, an ATmega8, some LEDs, Veroboard, assorted wires and solder and of course, a high-speed desk fan.

[shparvez001] also provides the full code on his blog for the project, making it very easy to replicate. Though we might also suggest you keep it small enough that the original fan cage still fits on top.

From an aesthetic point of view, the display looks fine in the dark — but when the lights are on you might get some odd looks. We can see this project being greatly improved by mounting the LEDs through one of the fan blades, and the control electronics on the back side of the other blades. Maybe throw in some wireless charging for the battery while the fan is off too?

Anyway, stick around after the break to see the display in action. If you want a more permanent fan POV try adding display hardware to a ceiling unit.

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A POV Spinner Display with Arduino

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[Martin2250] has been working on a spinning disc style POV display. He’s posted his progress up on reddit. This hack is a great example of using what you have at your disposal. [Martin2250] is using an IR LED and photodiode to determine the rotational speed of the disc. He tried using the Arduino micros() function to delay between the photodiode pulse and turning on his LEDs. As [Martin2250] found out, micros() isn’t quite accurate enough for this purpose.  He’s since switched over to using the AVR’s native timers, and is getting much better results.

The disc in this build is actually a CD. [Martin2250] sanded away the label, then masked out his digits. He “painted” the CD with a black marker. Peeling off the tape revealed his stylized digits. Cardboard, hot glue, and visible LEDs were used to create four light boxes for the digits. The disc can display any four digits at once – perfect for a POV clock. We love the use of on-hand materials in this hack – bits of hard and balsa wood, liberal use of hot glue, and of course cardboard. The only thing missing in our eyes is some duct tape!

POV Airsoft Turret on a RC Plane

To be honest, we’re surprised this hasn’t been tried before — then again, maybe it has! But what we do know is that the folks over at Flite Test have rigged up an electric Airsoft gun to a large RC airplane, aptly called The Kracken.

The planes are a scaled up version of their own FT Versa Wing, which feature two props, giving them the ability of differential thrust. Not only were they able to strap a semi-automatic Airsoft pistol on top, they also have two GoPros filming the action and giving the gunner a POV for shooting down the enemy plane! Don’t worry though, the enemy plane features its own weapon — A permanent marker! This hardly seems fair though, as the closer the marker gets, the easier shooting down the plane will be!

Don’t take our word for it though, check out the awesome video for yourself, after the break.

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CD-ROM POV Clock

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[Kyle] wanted to try something new. A Persistence of Vision Clock using a CD-ROM drive.

We have covered lots of POV Clocks that make use of hard drives, but we think this is the first time we have seen a CD-ROM drive used instead. [Kyle] points out that CD-ROM drives are typically much quieter than hard drives, which is the main reason he chose the CD-ROM route.

At the heart of this project is a good old ATMEGA168 and an RGB LED strip for the lights. To measure and maintain the rotational speed of the clock [Kyle] used an IR photodiode that detects a reference mark on the disc. An elegant build of a classic POV Clock, with a new twist!

The cool thing about this project is he did not actually use the CD-ROM drive like you think he would — he chucked the spindle motor and instead is spinning the disk using the tray ejection motor! He did this so he could control the motor by PWM straight off the microcontroller, whereas the spindle motor would require an IC and a varying control signal with specific voltage amplitudes.

He also experimented with different backgrounds and background lighting, which you can see in the video after the break!

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POV Pong game uses all kinds of smart design

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This little device lets you play some head-to-head pong using a spinning LED display. We’re really in love with the design. You get a pretty good idea of the Persistence of Vision aspect of the build by looking at this picture. But hearing [Dennis] explain the entire design in the video after the break has us really loving its features.

He’s using the head from a VCR as the spinning motor. The display itself uses a vertical row of LEDs with a bit of wax paper as a diffuser. These are current limited by a 1k resistor for each of the eight pixels. They’re driven by a PIC 16F690 but you may have already noticed that there’s no battery on the spinning part of the board. It gets voltage and ground from a pair of brushes which he fabricated himself. To avoid having to do the same thing to map the control buttons in the base to the spinning board he came up with something special. There’s a downward facing phototransisor which registers LED signals from the base to move the paddles up or down.

If you love this project check out the POV Death Star.

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HDD POV clock takes the best from those that came before it

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The concept behind this clock has been seen before, but [Dieter] tried to combine the best aspects of several projects into his HDD POV clock (translated). The basic principle of the design is to cut a slot into the top platter of the hard drive. This will let the light from some LEDs shine through. By carefully synchronizing the LED with the spinning platter a set of differently colored hands can be shown to mark time. We’ve been looking at the project for several minutes now and we’re not quite sure if the lines marking the 5-minute segments on the clock are generated in the same way as the hands, or if they’re marks on a faceplate on top of the platters. Check out the clip after the break and let us know what you think.

Past HDD clock project include this one, or this other one. Some of the design improvements include a better motor driver (which [Dieter] pulled from an old VCR) and the inclusion of an RTC chip to keep accurate time without the need to be connected to a computer. We also think it’s a nice touch to sandwich the hardware between two picture frames for a nice finished look.

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POV wheels for a longboard

If you don’t mind working with really small components this POV wheel project for a longboard will certainly attract some attention.

The name of the game here is small and cheap. Small because the wheels are only 72mm in diameter (about 2.8 inches). Cheap because [Ch00f] wants to produce and sell them locally. He went with an ATtiny24 microcontroller driving fifteen LEDs. Obviously this will present a problem as the uC uses a 14-pin SOIC package and that’s just not enough I/O to drive the LEDs individually. Add to that the issue of storing patterns to be displayed and you start to run out of program memory very quickly.

But obvious he pulled it off. The image above shows the wheel displaying the CT logo (for ch00ftech.com) and there are several other patterns shown off in the clip after the break. The LEDs are multiplexed, but the wheel spins fast enough that this turns out to be okay. The rotation is measured by an IR reflectance sensor aimed at the stationary axle. A CR2032 powers the device, with some counterweights added to keep the wheel balanced.

Our only concern is the fragility of the exposed electronics. But if you hit the right BOM price we guess you can just replace the board as needed.

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