Engineer Greg Davill has published a build for something rather trickier than an LED cube: an icosahedron, a shape with 20 sides featuring impressive 2,400 individually-addressable LEDs.
"The major challenge of making a smaller LED cube in my opinion is the LED panels. Commercially available panels are designed for video walls and typically made at 64x64 pixel as a minimum size," Davill explains. "This seems to be a good trade off between cost/complexity/light efficiency. On my previous project I had overcome one of the major hurdles of creating a smaller cube, because I had designed and built my own custom high density - less than 2.5mm pixel pitch — LED panels."
"So what next? I could make it smaller, improve the controller, improve the firmware. What about adding more sides? Inspiration came from this origami figure that I’d built many years ago and that has been sitting on my shelf. I’d never seen a LED icosahedron before..."
To build the 20-sided shape, Davill had to create an LED panel compact yet containing all the required electronics, shaped as an equilateral triangle with a system for easily daisy-chaining multiple panels together. These then needed to be placed in a 3D-printed enclosure with minimal exposed bezels, and while the controller from his earlier LED cube could be re-used it needed to be redesigned for a more compact form factor in order to squeeze into the icosahedron's smaller volume.
Design and assembly wasn't straightforward: An early error in the panel design required a second production run, while a footprint error meant that bodge wires were required for SOT-883-packaged MOSFETS. "That’s why I started using the saying 'this project has 300 bodge wires inside,'" Davill notes. "I’m not sure on exactly how long it took me to complete all the rework, but I did make it through a 60hr audio book that week."
Davill's full write-up is available on his personal blog.