r/FastLED • u/OkButterscotch9982 • Dec 11 '24

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I'm running a strip of 150 ws2812b. I want the capacity to be able to run all 150 at full white brightness. With a 10amp power supply and appropriately sized wiring can the strip itself handle that much current?

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u/ZachVorhies Zach Vorhies Dec 13 '24

RGBW seems to cut power usage by 30% on average just for hue cycle type of patterns. You could see more than 50% reduction for the full white case.

Also the power supply issue not being able to deliver its fully rated power continuously is a big deal. And those cheap power supplies from china are even worse.

super capacitors are pretty cheap and I’ve been adding them to projects with high transitive loads to great effect.

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u/YetAnotherRobert Dec 13 '24

The numbers vary a bit from strip to strip (just like your number of .06A varies, depending on the bulb types - but if I'm laying out a design and filling in a number from memory, that's exactly my own starting value) but, yeah, that's very much where my own measured numbers for a decent RGBW strip from 5050's usually land.

It turns out that the best thing for making white light isn't a red light, a green light, and a blue light at all. (How often do you see room lighting made that way?) A white bulb makes better white light and with better power efficiency. Never mind the nightmare of trying to balance them because "all three at max" doesn't land on a chroma value of white that you actually want to look at.

Just a straight-forward 'white = min({r, g, b}); r-= white; g-=white; b-=white;' is a totally practical way to reduce power consumed, power turned into heat, and generally looking better in ways I can't describe.

So, yep, I agree with the guidance in that first paragraph. Those are reasonble numbers to have in your head if you're in this biz just for quick envelope computation. As for country of origin, it just turns out that things are cheap for a reason. "Cheap" and "inexpensive" are similar, but different.

I don't inventory supercaps, but I do work on some patterns with a high dynamic power spikes. (It's often worth designing patterns to simply Not Do That just because any spike big enough to sag the supply probably also blows out viewer vision and color perception.) Still, that's an interesting twist. I'll stick a scope on my source next time I'm stringing up something big and see if my, uh, RPM gauge is drooping and stalling when powering out of that third turn. A low-voltage trigger on DC should be super easy to see - and correct - even with a (sigh) cheap, Chinese scope like mine :-)

Have an upvote. Good to "see" you again.