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.

32 thoughts on “Building The World’s Smallest RGB LED Cube

    1. so the leds are not the same orientation all the way up they are twisted round so it charliplexes,like all the rgb conections dont line up upwards then,i suppose this is the fidlyist bit making sure they are the right way round all way up,i havnt looked into it 100% yet ime waiting on leds etc and thin piano string like 0.2mm probly too thick but ile see when it gets hear lol

      1. Yup, each LED layer has to be rotated. Pay close attention to which directions the leds are rotated and which orientation they go onto the PCB. It has to be EXACTLY right or you would end up having to modify the code which would not be easy since it uses PORT commands that has been mapped EXACTLY for the wiring. I used ONE strand of a stranded cable. It was a bit flimsy even after I had all four wires, so you might want to look for slightly thicker wire. Good luck!

    2. I dont mean to be a big head but easy to solder them ive a fine tip solderer and i use bluetack to hold them steady i see what you mean about them not being square but its not to bad would be faster if they where square.you have done most the hard work routing the boards etc and code,so ile not show off to much as i know only half the battle is left.

          1. Yeah, these are TINY. Used the 1x1x0.2 mm Rohm Pico-RGBs in a design – lovely little bastards! Absolutely ridiculously small and really, really bright at only a few mAs. We had a reel laying around the lab, but can’t seem to find it now. Worst case, some fool threw ’em in the trash in the latest misguided “cleanup” in the lab event.
            Anyway, would also love to see a cube with those.

  1. First, thanks to Brian Benchoff and Hackaday for sharing my project. Second, please reply to this thread or the video on youtube if you remake this or make and even smaller one. I think it’d be really cool to see a ton of tiny cubes!

  2. This is the first project in ages that my first though was I want to build one and try to make it smaller!

    Well done sir. You have inspired me. All I need now is for this pesky snow stuff to go away so I have more free time to work on electronics rather then snowboarding. ;-)

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