A USB-Controlled POV Light Stick

Wanting to showcase their USB LED strip controller, the folks at Maniacal Labs built a POV LED stick this weekend. Yes, it’s pretty much the same as any other POV LED display you’ve seen; set a camera for a long exposure, wave the POV light stick around, and get a cool pixely image in mid-air. This build is a little different, though: it’s controlled over WiFi with a Raspberry Pi connected to a WiFi network.

The USB LED strip controller in question is the AllPixel, a small board that controls NeoPixels, WS2801, LDP8806, and a bunch of other LED strip controllers over USB. The Stick used for this project consisted of two meters of LPD8806 LEDs, giving 96 pixels of horizontal resolution. A big battery and Raspberry Pi rounds out the rest of the electronics.

Building a LED POV display isn’t that much different from building a LED matrix display; all you have to do is break up the image into individual columns and display them sequentially. To do this, the Maniacal Labs folks whipped up a LEDPOV class that does just that. To get the images, just open the shutter on a camera, wave the stick around, and if you get it right, you’ll have a great pixely image of nyan cat or the rainbow wrencher.

Simple POV Bike Effects with WS2811 Strips

[Andrew] wrote in with a new take on the classic persistence of vision bike spoke hack. While many of these POV setups use custom PCBs and discrete LEDs, [Andrew]‘s design uses readily available off-the-shelf components: WS2811 LED strips, an Arduino, an Invensense IMU breakout board, and some small LiPo batteries.

[Andrew] also implemented a clever method of controlling his lights. His code detects when the rider taps the brakes in certain patterns, which allows changing between different light patterns. He does note that this method isn’t incredibly reliable due to some issues with his IMU, so now he senses when the rider taps on the handlebars as well.

If you want to build your own bike POV setup, you’re in luck. [Andrew] wrote up detailed instructions that outline the entire build process. He also provides links to sources for each part to make building your own setup even easier. His design is pretty affordable too, coming in at just under $50 per wheel. Check out a video of [Andrew]‘s setup in action after the break.

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POV Display Does it on the Cheap

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[Sholto] hacked together this ultra low-budget spinning display. He calls it a zoetrope, but we think it’s actually an LED based Persistence Of Vision (POV) affair. We’ve seen plenty of POV devices in the past, but this one proves that a hack doesn’t have to be expensive or pretty to work!

The major parts of the POV display were things that [Sholto] had lying around. A couple of candy tins, a simple brushed hobby motor, an Arduino Pro Mini, 7 green LEDs, and an old hall effect sensor were all that were required. Fancy displays might use commercial slip rings to transfer power, but [Sholto] made it work on the cheap!

The two tins provide a base for the display and the negative supply for the Arduino. The tins are soldered together and insulated from the motor, which is hot glued into the lower tin. A paper clip contacts the inside of the lid, making the entire assembly a slip ring for the negative side of the Arduino’s power supply. Some copper braid rubbing on the motor’s metal case forms the positive side.

[Sholto] chose his resistors to slightly overdrive his green LEDs. This makes the display appear brighter in POV use. During normal operation, the LEDs won’t be driven long enough to cause damage. If the software locks up with LEDs on though, all bets are off!

[Sholto] includes software for a pretty darn cool looking “saw wave” demo, and a simple numeric display. With a bit more work this could make a pretty cool POV clock, at least for as long as the motor brushes hold up!

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The 128 Button, 6 Axis, 17 Slider, 4 POV Hat Switch Joystick Controller

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[Paul Stoffregen], creator of the Teensy series of dev boards, previously implemented a six-axis joystick for Teensyduino, the Arduino library for the Teensy. He had originally tried 8 axes, but a few problems cropped up, deadlines approached, and he left it as is. A few recent projects gave him some insight into how to implement a joystick with more than six axes as a USB HID device, so he started looking at how to read an improbable amount of pots and buttons for a USB joystick.

So far, the biggest problem is figuring out what software can actually use an HID joystick with this many controls. The answer to that question is none. The Linux-based jstest-gtk is able to read 6+17 pots, the four hat switches, but only 64 of the 128 buttons. A user on the Teensy forums, [Pointy], has been working on his own joystick test app that works on Linux Windows, but testing the joystick on Windows is an exercise in futility for reasons no one can figure out.

As for why anyone would want a six-axis, 17-slider, 128-button joystick, think about this: with this much control, it would be relatively simple to build the MIDI controller to end all MIDI controllers, or a cockpit simulator for everything from a C172, 737, to a Kerbal interplanetary cruiser. That’s an impressive amount of control, and all from a $20 Teensy dev board.

Further testing of this Teensy joystick is desperately needed, so if you’re able to help out drop a note in the forum thread.

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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