Has anyone reverse engineered how LED curtain hooks work?

Hardware
33

Just to add to this…

There seems to be 4 types of LED curtains we’ve identified in the wild: (“we” being the WLED MoonModules core team)

  1. Simple LED curtains with a return data wire. You can buy these “pebble” strands on AliExpress if you know where to look. Just solder the last pixel data-out to the return wire and pick it back up at the top.
  2. Curtains with fixed address pixels. These pixels are 3-wire but they don’t have a data-out. Installation is simple, but repair of a broken is difficult without a donor curtain as the strands are all permanently addressed at the factory. I personally use these extensively for large displays.
  3. Curtains with active T-connectors at the top. Those are detailed above. They seem to strip off X LEDs of output for the curtain strand (often 40 pixels) before sending the data stream to the rest of the curtain on data-out. 40 pixels may be simply reuse for some curtains I’ve seen with 40x40 pixels and they just reuse the same active T-connectors.
  4. Same as #3, except the circuitry required is now integrated into a WS281x-like LED at the top of the chain, inside the T-Connector. These are kinda weird in my opinion because they mix physical LED types (flat strip vs pebble). The ones we have for testing are also configured for 40 pixels but only use 20.

(And there’s possibly other variants as we haven’t seen any of the ones mentioned at the top of the thread with specifically numbered PCBs.)

#4 PCB detail:

IMG-20250105-WA0007
IMG-20250105-WA0007692×629 70.1 KB

Looking at #4 there’s 2 capacitors and 2 resistors. Data-in is connected directly to the strip that’s hanging down. This is curious because WS2812b only specify a 100nF decoupling capacitor per pixel, so I’m curious if the extra components in some way influence how long the strands are - is it possible to change the components and skip/split more or less pixels?

(I’ve also seen some on random Instagram reels that are around 60x60 curtains, so it would make sense that the chips are customizable in some way - but it was a very scammy advertisement so I don’t have info on the curtain they used in promo, which wasn’t what they were actually selling!)

There’s also some “prior art” here where someone was doing a similar thing several years back:

If anyone has some knowledge of the addressable pixel in the image above, I’d love to hear about it.

2 Likes