pixelboard64, try 2
In 2010, I worked on a project that required both flame effect controllers and very low resolution LED panels. The Heart Machine had 20 interactivity stations with touch-sensitive panels, requiring multiple participants at different stations to activate the flame effects. The panels were LED boards and a piece of metal screen behind acrylic; the screen was the line for a QTouch input, and the LEDs were controlled by three TLC5940 chips.
This was my first LED project, and I decided I wanted to make similar LED boards. However, the resolution was too low, so I decided to up the pixels from 4x4 to 8x8 in the same 6" square board.
The LEDs are Piranha/Superflux 5mm square RGB LEDs, chosen because they are very bright at a wide viewing angle.
The pixelboard64 worked out ok, for the most part. Due to a simple math error, the power regulator wasn't enough to power the entire board when all the LEDs were fully lit up. The TLC5940 chips were also very picky, and often weren't grounded well enough, causing them to burn out. Having 12 per board (at about $3.50 each) made these pretty expensive to play with and test, so progress kept on stalling.
This is what happens when you try to pull about 4A through a LM323 regulator that doesn't have a large enough heat sink on it:
Recently, I started working with WS2812 LEDs. Their low cost was enough to make me think about the pixelboard64 again - at $0.15/LED with no additional chips, instead of $0.50/LED with every 16 LEDs needing $10.50 worth of TLC5940 chips, it was worth another try. The board was shrunk to 4" square (half inch pixel density), and instead of using one big power regulator, I split it out to 4 UA7805 regulators.
The end result is a board where I can use a solder paste stencil and hot plate to quickly assemble the LED side, and then hand solder the power supply components to the back. 64 LEDs, super bright, and relatively cheap to make. For power, the board has a header for an Anderson Powerpole connector, to avoid the trouble of screw terminals.
Populated, the prototype looks like this. The camera can't really capture how bright the LEDs are - 64 of them all on at once is surprisingly bright.
Would you be interested in one of these boards? Depending on interest, I may organize a bulk order through Tindie or IndieGogo in order to cut down on costs, and maybe have them professionally assembled.