Point Source Pixels Remixed



Pixel String T Driver
Pixel String T Driver
Point Source Pixel
Point Source Pixel
Point Source Pixel
Point Source Pixel

The point source pixel design I came up with last fall has a lot of advantages: Small size, low power & good color mixing in a 10mm package. The hardest part was finding a way to chain multiple boards together. I’d done lots of tests by hand and found that building the wiring harness often took much, much longer than the actual board assembly. 


Life’s too short to spend days and days building a wiring harness.

So I redid the design… It ended up costing a few pennies more in components, but the time saved making wiring harnesses more than compensates.

Since each pixel has an on-board voltage regulator – and since the LED is driven from the processor directly – voltage drop within the cable is less of an issue than otherwise expected.

It’s based on a ‘backplane’ of 10-conductor ribbon cable. 4 conductors each for power and ground, plus a pair for DMX data.

It’s easy to lay out the cable, mark it every 6″ or 12″ and install IDC female headers as needed.

Since I was concerned that the high-speed data would be corrupted over long lengths of flat cable, I also designed a tiny DMX repeater / splitter board. It has connections for DMX in & through, plus an RS-485 receiver. Then, two RS-485 transmitters feed data to two separate 10-pin headers.

Each header connects to a female ribbon cable jack. So in essence, a string of lights can be driven from the center.

I expect to drive 16-18 pixels on each side of the ‘T,’ with each arm being 8-10 feet long.

Each splitter board will be connected to the control equipment two cables: a shielded, twisted pair for data and a heavy gauge pair for power.

~600 of these are being assembled by a shop here in town… Will post some video clips when it’s all installed.

 After taking the picture of the board + heat shrink tubing, I used a razor blade to trim the tubing back to the junction between the LED’s wider ‘neck’ and main bulb. This way most of the 10mm bulb is visible but the water resistant seal remains reasonably sound.

These are being mounted in the eaves, under the raingutter and near the soffit. It’s not designed to be fully submersible, just resistant to the occasional sideways-blowing blizzard.