Can anyone think of a good way to build a flexible power bus for a wearable?
Tossing around techniques for a led-embedded jacket, using 60 LEDs/m WS2812B strips, laid out in say 32 pixels by 20 strips wide (strips running from collar to hem down the jacket.) How do I get power from my power source (iPhone external battery packs) into the end of each strip?
The suggestion of making a power bus using thick copper braid would work well for a fixed, non-mobile piece, but having bare copper woven about the place in a flexible garment wouldn’t fly unless I could insulate it somehow. You don’t want shorts in your jacket, so to speak 
Anyone got any ideas they want to toss about?
Interesting, I didn’t know stuff like this existed.
As you note, probably not the answer, mostly because of the insulation issue—how do you tee off it every couple of cm without exposing uninsulated wire that’s carrying 5V @ up to 20A?
Use heat shrink to insulate or Kapton tape to cover up the exposed connections?
Eurgh, I can see where you’re going but man it’d be hard to make a neat job of that.
Perhaps, but instead of a T-connection, think of a Y-connection. You can slip heat shrink on the two legs that separate, then a single, larger one over the entire Y to cover it all up, then you bend one of the legs up 90 degrees. Everything’s insulated.
Or, get something like these: http://www.alibaba.com/product-detail/waterproof-T-connector_735641416.html
The other option is to have the two wires of the bus separated a bit, maybe half an inch to an inch apart. Then you can tie into each one without worrying that the exposed joints will touch one another. Just make sure the bus wires are well attached and won’t move.
Separating the bus wires enough to “guarantee” they won’t short just won’t be possible I don’t think. Though I could run the +ve rail across the top and the -ve rail across the bottom (but the whole thing would be flexible enough that this would still be a risk of shorting against the end of the strips.)
I see where you’re going with the “Y” arrangement but this too seems very fiddly, and hard to make running repairs after it’s all put together. I’d want the LED strips to be replaceable as a unit.
Consider the flat T-connectors I linked in my last post then. Especially since you want to be able to replace the strips. If you put the 4-pin headers on the strips themselves, you can plug/unplug them into the connectors very easy.
Will those t-connectors carry enough current though? And will the spacing end up right?
They’re originally designed for LED track lighting. As for spacing, that’s something you’ll have to figure out, I don’t know how far/close together you want them. You can always have two buses and alternate the strips.
Hmm, maybe some flat braid covered in heatshrink, pierced through with screws, using crimped spade connectors to join onto the power wires to the strips?
Putting the nut on the back side of the braid inside the heatshrink might be a good idea, that way it’s clamped against the braid ensuring good contact, then a washer outside the heatshrink, with the spade connector clamped between that washer and the head of the bolt.
I’d have to pre-drill a hole in the braid though. Bit fiddly to keep the nut in place while shrinking the heatshrink.
For my WS2812 matrices I simply run power along an edge, all in strips in parallel. I use a CAT5 24AWG twisted pair for each pole (i.e. 2x 24AWG wires each). On the opposite edge of the matrices I don’t bother running an additional power line as the strips themselves are capable, though I do wire those power lines in parallel the same way (again not directly wiring in a power line). So, for instance, one of my 40x52 matrices gets its power from just a single corner and has no reddening. Are you building in segments or a continuous spiral?
Now this I don’t get: 40 x 52 x 0.06 = 125A. I managed to make the insulation on 16AWG smoke with 35A. Without a bandolier of macho RC car batteries you’re probably not going to be able to produce 125A, but I don’t see how you’re going to get even a tenth of this current into the system on two strands of 24AWG.
Look at a standard computer power supply. There’s a reason there are several tails coming out of it as opposed to one single heavy power pair. You need to distribute the load across several wire pairs.
I get the impression that’s not what Erik is doing though.
I don’t go full white. The panels instantly get too hot! The patterns I show are a moderate overall current draw ~10A very max
Right, I see. I’m currently scaring the crap out of the denizens of http://electronics.stackexchange.com by following through the implications of a wearable project with 2048 .06A LEDs