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 project page.

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Link Trucker is a Tiny Networking Giant

If you’re a networking professional, there are professional tools for verifying that everything’s as it should be on the business end of an Ethernet cable. These professional tools often come along with a professional pricetag. If you’re just trying to wire up a single office, the pro gear can be overkill. Unless you make it yourself on the cheap! And now you can.

[Kristopher Marciniak] designed and built an inexpensive device that verifies the basics:

  • Is the link up? Is this cable connected?
  • Can it get a DHCP address?
  • Can it perform a DNS lookup?
  • Can it open a webpage?

What’s going on under the hood? A Raspberry Pi, you’d think. A BeagleBoard? Our hearts were warmed to see a throwback to a more civilized age: an ENC28J60 breakout board and an Arduino Uno. That’s right, [Kristopher] replicated a couple-hundred dollar network tester for the price of a few lattes. And by using a pre-made housing, [Kristopher]’s version looks great too. Watch it work in the video just below the break.

Building an embedded network device used to be a lot more work, but it could be done. One of our favorites is still [Ian Lesnet’s] webserver on a business card from way back in 2008 which also used the ENC28J60 Ethernet chip.
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The Best Projects That Fit In A Square Inch

A few years ago, we started as a project hosting site for The People Who Actually Make Stuff™, and since then we’ve been amazed by what the community can put together. We have well over 100,000 hackers on board in an awesome community. Sometime around September, a few members of the community decided to follow in the footsteps of the very successful contests we’ve had on This led to the Square Inch Contest, a challenge to put the coolest electronics inside a square inch PCB. An inch the distance light travels in 1/11802852665.12644 of a second for those of you without freedom units.

The winner, Quadcopter In One Inch

With almost eighty entries, the judges had a very difficult task ahead of them. In the end, only one project would be the best. The winner of’s first user-created contest is Quadcopter In One Inch from [jeff]. This wins the grand prize of a $100 credit for the Hackaday Store and a $50 gift certificate to OSHPark.

There are six other prizes, each receiving a $50 credit to the Hackaday Store and $25 for OSHPark:


The judges for the Square Inch Project would like to give an honorable mention to Twiz and the blinktronicator. The judges would also like to express amazement in how much work actually goes into judging a contest on Spending a few weeks working on the judging for a contest with eighty entries imbues a sort of respect for people who can judge a contest with one thousand entries in three days, as the Hackaday crew has done with two Hackaday Prizes so far. While they were doing that, I was sitting back and cracking jokes about Fleiss’ Kappa.

This was the first community-created contest on, but it is surely not the last. We don’t know what the next contest will be – that will be up to someone on – but there will be one, and like the Square Inch Project, it will be awesome.

This Project Will Be Stolen Again

The Travelling Hacker Box is the physical implementation of the community. While most of what happens on happens online, sometimes the activities leak out to the real world. One such activity is a box, filled with random electronics stuff, shipped around to different members of the community.

hackerboxIt’s a great idea in theory. In practice, people are bastards. The first Travelling Hacker Box was stolen by a member of the community. After travelling 14,167 miles through Philadelphia, San Francisco, Boston, Seattle, New York, Boston again, and the middle of Texas, the first travelling Hacker Box met its fate along the Georgia border, two hours outside of Atlanta. Who is responsible? We’re not going to talk about him. He knows who he is and what he did.

All is not lost, even though hundreds of dollars in electronic doo dads are. There’s a new Travelling Hacker Box already on its way around the US. It’s slowly being filled up with goodies, and has already visited Wyoming and upstate New York, and is currently somewhere around Anchorage, AK. The latest update shows this box is filled with goodies including a mini CRT assembly from an old camcorder, stepper motor drivers, and other weird electronics paraphernalia.

The travels of the current Travelling Hacker Box
The travels of the current Travelling Hacker Box

The current plan for the Travelling Hacker Box is the same as the old box: put 25,000 miles on the odometer while taking advantage of the economics of a USPS flat-rate box. From there, it will go further afield, travelling the circumference of the Earth a second time, hitting stops in Europe, Africa, Asia, India, Australia, and South America. If you’re a subcontractor for Raytheon, part of the NY Air National Guard, or are otherwise able to receive mail in Antarctica, you are encouraged to email me.

Feel like you’re up for adding a few hundred miles to the Travelling Hacker Box? There’s no set process to get on the list; destinations are chosen by distance from the current node, trustworthiness, and distance to the next node, if planned. The best way to get on the list is to click the ‘Request to join this project’ link on the Travelling Hacker Box project. Then, hang out in the Hacker Box chatroom, and you might have a chance at receiving a magical box of random electronics.

The Hackaday 2015 Omnibus: A Puzzle So Dense, Even We Don’t Know The Answer

Print is dead, so we put a skull on it. That’s the philosophy behind the 2015 Hackaday Omnibus, the printed collection of the best Hackaday has to offer.

We have a few ideas of where we would like to take the print edition of Hackaday. Mad magazine-style fold-ins are on the list, specifically a fold-in style schematic that does two completely different things. Remember when records were included as a magazine insert? Those are called flexi-discs, and there’s exactly one company that still does it. All of these and more are plans for the future, and for the 2015 Hackaday Omnibus, we chose to include something we’re all very familiar with: a puzzle. This is no ordinary puzzle – even we don’t know what the solution is.

The first clue on the front cover of the 2015 Omnibus

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Mains Powered 3D Printer Heated Beds

Converting mains voltage down to 12 or 24VDC to drive a heating element makes no sense. To get 120 watts at 12 volts requires thick wires that can handle 10 amps, whereas at 120V, tiny 1A wires will do. If you’ve ever felt the MOSFET that switches your heated bed on and off, you know it’s working hard to pass that much current. [Makertum] is of the opinion this is a dumb idea. He’s creating a 110 / 230 V, mains-powered heated bed.

Creating a PCB heat bed isn’t an art – it’s a science. There are equations and variables to calculate, possibly some empirical measurements by measuring the resistance of a trace, but Ohm’s Law is a law for a reason. If you do things right, you can make a PCB heat bed perfectly suited for the task. You can even design in safety features like overcurrent protection and fuses. It can’t be that hard. After all, your house is full of devices that are plugged into the wall.

However, there’s a reason we use 12V and 24V heated beds – they give us, at the very least, the illusion of safety. Therefore, [Makertum] is looking for a few comments from specialists and people who know what they’re doing.

Although a mains powered heated bed sounds scary for a hobbyist-built 3D printer, there are a number of positives to the design. It would heat up faster, thin down a few parts, and significantly reduce the overall cost of the printer by not requiring another 100 Watts delivered from a 12V power supply. It’s a great idea if it doesn’t burn down the house. Anyone want to help?

Decypering The Illuminati

A few months ago, a strange account popped up on Whoever is behind this count is based in Bielefeld, Germany – a place that doesn’t exist. They are somehow related to the Berenstain / Berenstein Bears dimensional rift, and they may be responsible for giving Cap’n Crunch only three rank insignia on his uniform. There is something very, very strange about this account. Since August, a black and white image of static, 98 pixels wide and 518 pixels tall has sat on this account profile. The Illuminati has given us enough clues, but until now, no one has managed to crack the code.

The first person to make sense out of the patterns in static is [Moritz Walter]. What’s in the code? More codes. While that’s not really helpful, it is to be expected.

SecretCodes2The hackaday illuminati included one additional piece of information with their encoded static image: a 12×12 pixel bitmap. When this bitmap was XORed with the main image, symbols appeared. In total, there are only seven unique symbols in the image. These symbols seem to be stolen from the Fez alphabet, but there are some significant differences. These symbols are rotated multiples of 90 degrees, and are surrounded by a one pixel border that is either black or white (we’re calling the border a ‘sign’ bit). In total, these seven symbols arranged in four different rotations with two different signs yields forty unique variations of a symbol in the decoded image. At this point, it should be noted 7*2*4 = 56.

As of now, cracking the illuminati’s cyphered machinations has hit a roadblock. There’s a dead image file on the illuminati’s profile. Until that image is rehosted, there is no way to progress any further. That’s not going to stop people from trying, though: the chat channels on have been buzzing about the newly decrypted images. Hopefully, with time, someone will figure out what it all means.