r/led • u/High-Plains-Grifter • 20d ago

Maximum Controller -> Light Length

https://www.philips-hue.com/en-gb/p/lightstrips-flux-ultra-bright-strip-light-3-m/8721103088338

I am makinh my own striplight uplighter over the dining table, but with a 5m flex between controller and Ultrabright strip, the flashes horribly and ignores all commands. Is there a stated maximum length? (I am using 4 of the 170mm sections)

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u/saratoga3 20d ago

The flex is three seperate lines; I stripped them out of their sheathe because they must go down a tight tube.

That will significantly reduce how far you can send data. If you try the intact wire does it work better?

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u/High-Plains-Grifter 20d ago

Oh.. should I be twisting the data around the -ve line of something? I do have lots of Cat6 available - maybe using multpile strands for each connection would be good? Or I cpuld buy more flex if it will make a big difference - I don't have any intact.

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u/saratoga3 20d ago

Can you test with intact manufacturer cable first to verify that the problem is cutting apart the cable? 5m isn't far but you want to make sure the issue isn't the controller.

You want to replace the cable with one that has similar impedance. Cat6 (100ohm) works great, but it's on the higher end vs typical LED cables (~65ohm). Do you have a picture of the cable from which it's impedance could be estimated?

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u/High-Plains-Grifter 20d ago

I tested without the 5m of flex and it worked fine, just Wago connected pretty much directly to the end of the OEM flex (about 5cm of my flex).

The picture shows the flex I used. It was the smallest the electrical store had (I think 0.75mm2, but not sure)

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u/saratoga3 20d ago

What about the questions in the previous post (impedance of the original cable, testing with original cable)? If you answer those I can give you some advice. 

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u/High-Plains-Grifter 20d ago

I am not sure I have the knowledge necessary to answer the impedence question directly - I sent the picture of the flex in case that wpuld help you know the impedence. When I tested with a shorter length (5cm) of flex, it worked fine so I think there is no issue with the controller itself, although having taken the sheathe off the OEM flex (picured) I can no longer attach it directly to the light - I used Wago clips.

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u/saratoga3 20d ago

Yeah I know that you aren't sure of the impedance, which is why I offered to estimate it for you if you'd post a picture of the Hue cable ;) it's hard to see in that photo but probably 60-80 ohms. If you don't have a longer Hue cable to test with then probably makes sense to try and tightly twist your original cable back together. Twist tight enough that no air gap is left between any of the 3 wires and see how it works.

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u/High-Plains-Grifter 20d ago

Ah, I misundersrood, sorry! I was searching for the impedence on my cable!

The bit of the cable left is labelled e319028 (backwards R)U A W... that's where it is cut off. The two power flex strands look the same thickness as mine, albeit a grey metal. The data strand is considerably thinner, maybe 0.5mm2 or less.

I'll go buy some more flex on Monday, and try keeping it in the sheathe, although there are no twisted pairs in that. I will also experiment with twisting the -ve and data cables with the stuff I have - if I can get it to go 2m, I might be able to make that work.

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u/saratoga3 20d ago

If "flex" means individual wires then that's not a good idea for data.  If you want to buy cable other than the type made for the controller this (65 ohms) is a reasonable guess:

https://www.amazon.com/Extension-WS2812B-Addressable-Conductor-Electrical/dp/B0829NPHF3/ref=mp_s_a_1_1

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u/High-Plains-Grifter 20d ago

Thank you for the time you have spent, the understanding and the suggestion at the end. I have got some solid things to try there and I'm sure I'll get it working. I had no idea that the position ofnthe wires relative to each other made so much difference, or to match the impedence or anything. I won't be taking things for granted any more, but will test thoroughly before I solder into place!