Laser-etched LED Zeotrope Looks Like A Circular Monochrome Screen

October 3, 2012 by Mike Szczys 12 Comments

The still image of this animated display really doesn’t do it justice. But you can get an idea of how this really does look like an old monochrome display. It’s actually a zeotrope made from LEDs and etched acrylic. The LEDs blink at a rate that synchronizes with the spinning acrylic to produce an animated image.

You probably already know that a zeotrope uses moving physical models to trick the eye into seeing an animation. In this case the models are etched into a piece of acrylic so that their outline glows when the material is edge-lit. Twelve pie piece shaped panes were designed in Inkscape to look like a scene from the Linux game World War IV. A stepper motor spins the ring which allows for the perfect synchronization seen in the clip after the break.

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Nixie Suduku And On-die LEDs

October 2, 2012 by Brian Benchoff 18 Comments

The best booths at Maker Faire draw you in with something unbelievably cool or ridiculously absurd, and bring out a state-of-the-art technology just as your curiosity for the main feature starts to wane. [John Sarik]’s booth for a class he’s TAing at Columbia – Modern Display Science and Technology – is one of these booths.

The main feature of the booth is a suduku board filled with 81 Nixie tubes. As shown in the video below, you control the cursor (the decimal point of the Nixies) with a pair of pots. After moving the cursor to the desired location, there’s a keypad to change the number at any one of the 81 locations on a suduku puzzle.

[John]’s presentation then continued to what he’s working on up at Columbia: he’s working on a project to put arrays of LEDs onto silicon, just like any other integrated circuit. He demoed a small LED display built in to a DIP-40 package with a glass (or maybe quartz) window. Yes, it’s a really tiny LED matrix display with a pixel pitch probably much smaller than a traditional LCD display.

Video of the suduku machine after the break, as well as a gallery of the LED matrix on a chip. The matrix was very hard to photograph, so if [John] would be so kind as to send a few more pics in, we’ll be happy to put them up. There’s also a proper video from [John]’s YouTube showing off the Nixie Suduku puzzle solving itself with a recursive algorithm.

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Build A POV Death Star, You Will

October 1, 2012 by Mike Szczys 26 Comments

Building a Persistence of Vision globe is pretty awesome, but overlaying a Death Star pattern on the display takes it to the next level of geekery. Like us, [Jason] has wanted to build one of these for a long time. His success pushes us one step closer to taking the plunge and we hope it will inspire you to give it a shot too.

As he mentions in the beginning of his write up, the mechanical bits of these displays are really where the problems lie. Specifically, you need to find a way to transfer power to the spinning display. In this case use went with some DC motor brushes. These are replacement parts through which he drilled a hole to accept the metal axles on top and bottom. We hadn’t seen this technique before, but since motor brush replacements are easy to find and only cost a few bucks we’d say it’s a great idea.

The 24 blue LEDs that make up the display are all on one side of the PCB. They’re driven by an ATmega328 running the Arduino bootloader. [Jason] uses an FTDI adapter to program the chip. Don’t miss the video embedded after the break.

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StarGate Eggbeater

September 24, 2012 by Eric Evenchick 5 Comments

[Jason] used a strip of 142 Adafruit LPD8806 Addressable RGB LEDs to create the StarGate Eggbeater persistence of vision display. The LED strips are controlled by an Arduino Mega, which is used to control the strip and provides 21 bit color control for each LED. The strip is housed into a ring-shaped tube which is mounted onto a rod and bearing to allow it to spin. A 1/4 HP motor is used to spin the ring at 250 RPM creating the POV effect.

One issue when controlling a spinning object is making electrical connections to a spinning object. The LPD8806 requires four connections: power, ground, clock, and data. To make the connections, [Jason] used a MOOG Slip Ring. This allows for the four connections to be made while the ring spins at 250 RPM.

Of course POV demos need videos, so check one out the “boss program” video after the break.

Via Adafruit

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LED Array Uses Ridiculous Amount Of 14-segment Displays

September 23, 2012 by Brian Benchoff 29 Comments

What do you do if you see a bunch of 14-segment LED displays for sale for a penny a piece? [Fritzler], when faced with that conundrum did what any of us would do – he bought 64 14-segment displays and built a huge 16×4 alphanumeric display (German, here’s the translation).

[Fritzler] found a cache of old East German 14-segment displays for €0.01 at electrobi.de (don’t bother, they’re out of stock), and the only thing he could think of was building a gigantic display. He used ULN2803 Darlington drivers for each LED module, but there was still the issue of controlling the entire display.

For that, [Fritzler] decided to make his 16×4 use the same protocol as the Hitachi HD44780 LCD controller. This meant [Fritzler] could wire up his gigantic, power-hungry display to a microcontroller as if it were a simple LCD display.

An amazing amount of work went in to the creation of this display, as evidenced by a pair of pictures showing what [Fritzler] had to solder.

Thanks [freax] for sending this one in.

Communicating With A Beam Of Light

September 22, 2012 by Brian Benchoff 39 Comments

Last weekend, ARRL, the national association of amateur radio, held a contest called, “10 GHz and up” with the goal of communicating via radio or microwaves over long distances. [KA7OEI] and a few friends decided to capitalize on the “and up” portion of the ’10 GHz and up” contest by setting up a full-duplex voice link over a distance of 95 miles. They used the 478 THz band, also known as red LEDs and laser pointers.

With [Ka7OEI]’s friends [Ron] and [Elaine] perched atop a 5700 foot-high mountain near Park City, Utah, [Gordon], [Gary] and [KA7OEI] trudged up a hill about 10 miles north of Salt Lake City. With the help of a pair of 500,000 candlepower spotlights, the two teams found each other and began pointing increasingly higher power LEDs at each other.

The teams started off with 3 Watt red LEDs before moving up to 30 Watt LEDs and a photodetector at each end. Even though the teams weren’t working with a true line-of-sight – refraction of the atmosphere allowed them to transmit this far – they were able to transmit tone-modulated Morse and even full-duplex voice.

Not bad for a transmission that bends the FCC’s “275 GHz and up” amateur band to its breaking point.

Using An Undocumented Display With An FPGA

September 19, 2012 by Brian Benchoff 11 Comments

When [Mike] ran across a display on Deal Extreme with 8 seven-segment displays, 8 red/green LEDs, and 8 buttons, he knew it would find a good home in a future project. There was only one problem, though: except for an Arduino library, there was absolutely no documentation available for this display. Wanting to use this display with an FPGA board, [Mike] decided against bit-banging a protocol and ported the C++ code into a hardware implementation.

This Deal Extreme display, the TM1638, features enough seven-segment displays, LEDs and buttons to build something really cool, and surprisingly isn’t terribly hard to interface with a microcontroller. The TM1638 library communicates with the outside world via only three pins and a simple serial connection.

After figuring out what commands are sent to make the display turn LEDs on or off, [Mike] wrote a hardware implementation for his Digilent Nexys2 and Digilent Basys2. Now the display operates on an FPGA just like it does with an Arduino, and is a great tool for debugging HDL code for [Mike]’s FPGA.