Building The World’s Smallest RGB LED Cube

What’s the smallest RGB LED cube? A 1x1x1 cube is easy, but it’s a stupid joke and we’ve heard it before. No, to build the smallest LED cube, you’ll have to stuff 64 RGB LEDs into a cubic inch, like [Hari] did with his miniscule LED cube.

A single column of Charlieplexed LEDs. Note the resistor for scale.
A single column of Charlieplexed LEDs. Note the resistor for scale.

One might think that individually addressable RGB LEDs are the way to go with an LED cube this small. Anything else would hide the LEDs behind a mess of wires. This isn’t the case with [Hari]’s LED cube – he’s using standard surface mount RGB LEDs for this build. But how is he connecting the things?

The entire build was inspired by the a much earlier project, the Charliecube. This LED cube, like [Hari]’s uses Charlieplexing to condense all the connections for a column of LEDs to only four wires. Repeat that sixteen times, and [Hari] built himself a tiny, one-inch cube of glowey goodness.

The cube itself was built with a PCB backplane designed in Eagle and fabbed at OSHPark. The LEDs are driven by an Arduino Nano. If you’d like to build your own, or you’re a masochist for dead bug soldering, you can grab all the design files over on [Hari]’s hackaday.io project page.

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A Vase of Ice and Fire

When we first saw [Ginko Balboa]’s vase of ice and fire, we weren’t that impressed. Until we realized that the whole vase was a glass, copper, and solder circuit with LEDs sandwiched in between. The tutorial starts with [Ginko]’s technique for etching a custom board for the base circuit. It gets interesting with the construction of the LED circuit.

First a glass bottle was scored in a pattern and shattered, leaving a jigsaw puzzle. Two differently colored LED light strips were desoldered. Then, from the bottom up, the glass was taped around with an adhesive backed copper tape, and soldered together. Every now and then an LED was soldered between the carefully separated areas of the circuit. Some LEDs were soldered in one way, and some the other. This way the vase could be rotated on its base to select a different color. Once the outside of the vase with the LED circuit inside it was finished, another cut bottle was put in the center and soldered in a final position, making the assembly waterproof.

The final product is really interesting, and we’re scratching our head to figure out if there’s anything else this technique of circuit building could be used for. Ideas?

Scrolling a Message on a Building in a Time Lapse Video

[Saulius Lukse] has a really interesting way of turning a couple of buildings into his own addressable display. The effect is not seen in real life, but is a clever video rendering with stock he pulled from time-lapse cameras. Now if you want to play Tetris using the windows of a building you add wireless lightbulbs to every window. But that’s a lot of work. You can fake playing Tetris (or scrolling messages in this case) if you just show a video of the buildings and swap in your own image manipulation.

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[Saulius] starts with a time lapse sequence of a city scape. It needs to be one with a large building or two to provide a good scrolling surface. The building is extracted from the scene with the background transparent. The really time consuming part is creating a distinct image with one window lit for each window that is going to be used. This set of windows are the ‘pixels’ used to create the scrolling images. This is accomplished by masking out one image of the building with every office light turned off, then masking out each window individually with the office illuminated. This masking means everything going on around the building (traffic, weather, people) will be preserved, while the windows can be individually manipulated.

Next the program jinx is used to create the building animation. This program is designed to create scrolling messages on LED panels. [Saulius] provides a Python script that takes the images, the output of jinx, and combines them to create the final set of moving images.

The result is a city wishing you a “Happy New Year!”

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The Newest Graphing Calculator Game

Certainly everyone remembers passing time in a boring high school class playing games on a graphing calculator. Whether it was a Mario-esque game, Tetris, or BlockDude, there are plenty of games out there for pretty much all of the graphing calculators that exist. [Christopher], [Tim], and their colleagues from Cemetech took their calculator game a little bit farther than we did, and built something that’ll almost surely disrupt whatever class you’re attempting to pay attention in: They built a graphing calculator whac-a-mole game.

This game isn’t the standard whac-a-mole game, though, and it isn’t played on the calculator’s screen. Instead of phyiscal “moles” the game uses LEDs and light sensors enclosed in a box to emulate the function of the moles. In order to whack a mole, the player only needs to interrupt the light beam which can be done with any physical object. The team made extensive use of the ArTICL library which allows graphing calculators to interface with microcontrollers like the MSP432 that they used, and drove the whole thing with a classic TI-84.

This project is a fun way to show what can be done with a graphing calculator and embedded electronics, and it was a big hit at this past year’s World Maker Faire. Calculators are versatile in other ways as well. We’ve seen them built with open hardware and free software, And we’ve even seen them get their own Wi-Fi.

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Cricket Scoreboard is a Big Win for Novice Hackers

The game of cricket boggles most Americans in the same way our football perplexes the rest of the world. We won’t even pretend to understand what a “wicket” or an “over” is, but apparently it’s important enough to keep track of that so an English cricket club decided to build their own electronic scoreboard for their – pitch? Field? Help us out here.

This scoreboard build was undertaken by what team member [Ian] refers to as some “middle-aged blokes from Gloucestershire” with no previous electronics experience. That’s tough enough to deal with, but add to it virtually no budget, a huge physical size for the board, exposure to the elements, and a publicly visible project where failure would be embarrassingly obvious, and this was indeed an intimidating project to even consider. Yet despite the handicaps, they came up with a great rig, with a laser-cut acrylic cover for a professional look. A Raspberry Pi runs the LED segments and allows WiFi connections from a laptop or phone in the stands. They’ve even recently upgraded to solar power for the system.

And we’ll toot our own horn here, since this build was inspired at least in part by a Hackaday post. The builders have a long list of other links that inspired or instructed them, and we think that says something powerful about the hacker community that we’ve all been building – a group with no previous experience manages a major build with the guidance of seasoned hackers. That’s something to feel good about.

Hacker Welcomes Grandaughter with Web Enabled Frame

We all have different ways of expressing excitement about new family members. [viscomjim] expressed his joy at the arrival of his first grandchild by building a twitter-enabled mirror/mood light. While we’d like to rage that this Internet of Things “thing” that people are doing has gone too far, this isn’t the first time we’ve seen this happen.

For the brains of his device [viscomjim] used an ESP8266 module. [Viscomjim] etched his grandchild’s name into the mirror and put some Neopixels behind it. When one of his family members tweets to the light’s channel they can change the color of the light to interact with their newest family member. We’re not so certain the Internet won’t find this and turn it into baby’s first 24 hour rave.

If you’d like to get in on the ESP8266 action, you’ll find the Huzzah board a good start, and we’ve got a special Hackaday edition in the store. Just sayin’.

Reverse Engineering A Real Candle

[cpldcpu] just can’t leave the mysteries of candles alone. We’ve covered his explorations of candle flicker LEDs before, but this time he’s set his sensors on the real thing. [cpldcpu] hooked a photodiode to his oscilloscope, pointed it at a candle flame, and recorded the result.

The first interesting observation was the candle slowly changed brightness, whether it was interacted with or not. Next he measured the effect when the flame was disturbed by small gusts of air. This produced a bright flicker with an oscillation at 5Hz before returning to steady state, which as [stygiansonic] mentioned in a the Hacker News comment, is a known phenomenon used in flame detectors. Neat! There’s even an equation:

Under normal gravity conditions, the flames have a well defined oscillation frequency which is inversely proportional to the square root of the burner diameter, D, and to a good approximation can be written as f » 1.5/D½, with D given in meters.

[cpldcpu] then compiled his measurements into a series of graphs and ultimately an animated gif comparing the candle steady state, a real candle’s flicker, and the flicker he recorded from a candle flickr LED. It’s surprising how different the fake is from the real thing. You can look at his measurements and code at his github.

[via Hacker News]