Power and Wiring 2812b: Multiple Power Supplies; Grounding; Power Injection

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I know there are multiple threads here on these topics but I wanted to address a specific interest I have.

I’ve now read quite a bit about powering these 5V systems, proper grounding and indeed ground loops.

It seems to me that power injection itself introduces a kind of ground-looping. Anyway, I need a super stable system with minimum possibility for downtime. So here is a proposed schematic. I’d be super happy to hear your thoughts. Liberal application of red ink is welcome!

Wiring Schematic 1.pdf (200.4 KB)

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Everything definitely needs a common ground.

I like the idea of a common +5V but I suspect that there could be some heat as a result of imbalance. So keeping the power for the strips and PBs separate makes sense to me.

Where did you read about proper grounding and ground loops? I’d love to be able to actually understand it instead of imagining it’s a bunch of garden hoses and where is the water flowing!

(I’m injecting power at 4 points from 3 different 2-prong wall sockets which may or may not be on the same house circuit. The middle two points are fed from the same 10A supply, with one on a long extension cord. It’s a complex setup so I’m wondering whether I should expect a potential difference across the strips. They’re not hot when off … but maybe I should get a multimeter and actually check :relaxed:)

As for the multiple PB question, that’s a question of how complex your patterns are, what rate you want, and the slight extra complexity of syncing the PBs.

Also have you fed it into Pixel Light Power Calculator ?

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The 5V+ common is, I think suspect as long as there is ample power to each dependent set of strings. Leaving it out offers lower, but still high, potential for overamping if there is a short. So, I don’t really see an advantage to adding it. Maybe some kind of “balancing” thing.

Basically, it seems all neutrals should at best home run back to the PS… which make for a god awful mess of wiring that I am trying to hide in tubing… :frowning:

But there’s the neutral that’s supposed to follow along with the data line… best, I hear, as a shielded or twisted pair… That can be considered ??? as a neutral completely separate from the others, if the PB is isolated??? Dunno.

Basic principles would have it that we do NOT want any appreciable current returning to the OE and PB, but running back to the Power supplies… So how do we avoid this built-in ground loop? Is that what the resistors are for in the OE?

And… the thing is that none of this really goes to ground, its a DC circuit after all.

So, and in a related topic, how does one design a DC/LED system for static dissipation?

Anyway lots of Qs here. I, know we’re meant to fiddle with it ‘till w3e get some spits und sparks und out-gepoofiin’! (Been there done that!)

In any case here are some references I dug up including discussions here -

https://electronics.stackexchange.com/questions/192550/ground-loop-explained

https://electronics.stackexchange.com/questions/127626/does-the-ground-line-in-a-dc-circuit-carries-current

And these great discussions here -

https://forum.electromage.com/search?q=common%20ground

Finally, I have fed measured data into that Pixel Light Power Calculator and found the results strongly depend on messing with the total intensity (pretty far from actual) to get the results to get close to approaching observed. Please see These results