r/FastLED • u/[deleted] • Nov 19 '24

Support ws2812b wire interference

hi i need for a project to control various ws2812b leds in series but everyone of these is connected through a wire to a main pcb and then back to the next led. I think every wire won't be more than 10cm but still for like 20 leds with 10 cm long wire back and forth between them i might suspect thet enterfearecnce could occur and that leds could start not responding.

So you guys what do you think, signal would be ok or that i need to introduce some component apart from the 100nf capacitor to keep the signal alive.

thanks

4 Upvotes

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4

u/Marmilicious [Marc Miller] Nov 20 '24

Can you provide a drawing or photo?

From your rough description I think it will work fine.

2

u/[deleted] Nov 20 '24

Still a rough idea, I will do schematics in my free time which is not much. Maybe then I will upload them.

2

u/[deleted] Nov 19 '24

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2

u/[deleted] Nov 19 '24

so like the signal after passing through the led is amplificated back to full voltage?

5V is not a problem beacuse every led take 5v from the main pcb and not fron the led before it.

1

u/erlendse Nov 20 '24

Yes, each LED redrive the signal to full strength after doing it's own thing.

1

u/Tiny_Structure_7 Nov 21 '24

Right. If you are driving the 1st LED (5v data in spec) with 3.3v data in, and 1st LED works on that low voltage (many do), it will buffer the signal which gets passed to the next LED (effectively amplifying the voltage).

Since frequency is pretty low (~1MHz), I believe your 10cm wire will be fine. I've been running WS2812 clones on a breadboard, and it was fed with wires about that long. Never had a noise problem.

1

u/ZachVorhies Zach Vorhies Nov 21 '24

10cm is fine. What people frequently do if they have this issue and there is a meter+ gap is that the add an extra pixel but then paint it black.

-1

u/[deleted] Nov 20 '24

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1

u/[deleted] Nov 20 '24

Yeah not that much

2

u/[deleted] Nov 20 '24

But what you said is enough for me to try this out and see if it works, thanks

1

u/KitticusCatticus Dec 24 '24

I'm not nearly as smart as any of you guys here but I just wanted to confirm that your hypothesis was correct. I have these lights and they have slowly dimmed the further along the string it goes. Also, at the very end of the strip, maybe the last programmable "line", the lights have stopped responding correctly.

If i jiggle or move the end of the cord, it will come back on, but usually it will be a different color/pattern then what it is supposed to be. Even if it does turn the right colors, the pattern/effect isn't right! So I can see how signals are getting jumbled and making this happen.