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Threshold point on when to eject power?

CLD Kevin

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Just curious at what point do you inject power? For me, anything below 10V DC if using 12V source. I believe the LEDs will work as low as 9V, but don’t let it get that low.


I ran a test today using 2811 string with 4in spacing using 20awg wire. 16ft of pixels or 25ft total length from end-2-end. From the controller to the first pixel was about 8ft. Going in was 12.08V DC….coming out after 50 pixels was 11.30V DC. Not bad…loss of only 0.78V DC. I then added another 2811 50ft string in series. They all worked but coming out the far end after 100 pixels was 9.20V DC. The 2nd string lost 2.1V DC. I’m sure the longer distance itself (50ft total) played a good part for the higher loss.


I was planning out a 30ft mega tree and usually would inject power on the second string because its below my set threshold, but wondering if anyone ran something like this with no issues? Would save me time and $$ if I didn’t have to inject the top half of the tree. Maybe 100 pixels is too much and no more than say 75 pixels would work?



Here is another question related to power….


The 2811 strings I tested with all 50 pixels at 100% on was 2.7A DC. Using all 16 outputs on an E682 would require 43.2A if using 50ft pixels per leg. Now with that said…..my plan based for a 30ft tall and 12ft diameter base was to use 128 50ct strings. 64 strings around the base and each sting are doubled in length. Based off calculations, the spacing between each string would be 7in. About 19K channels.  So using 4 E682 will get me there channels wise with extra….no problem. But 2.7A X 128 = 345A?? Am I over thinking this? This would be the max power required if I turned on every pixel white. Honestly don’t know the chances of that happening but better to be safe. I can cut in half and go with 32 strings around the base. This would cut the power requirement to 172A but the spacing would be 14in. Still seems like a whole lot of 30A power supplies to run 1 mega tree. And it does have to be a 360 tree. Viewing is from all around.



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Damn, that's a lot of pixels!  My math agrees with yours.  One thing you did not mention is total current for each E682.  Assuming you are feeding a 100 pixel string for each output, the total current for each E682 would be 86.4 amps in a worst case situation.  That exceeds the total current rating for an E682.  That might be a reason to inject current.


That is what I am planning - assuming I do as planned for 2015 and take my pixel tree from 12 to 16 strings, and from 50 to 100 pixels per string.


I realize that we're talking about the worst case situation.  However in 2014, I did have one spot where all 600 pixels were full white - although only full for one second before it started ramping down over the next 5.

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The passed 2 years I've ran a 16 string x 50 pixel mega tree, plus 270 dumb nodes from a single 60 amp power supply. This one is 5v but in reality, that's about what a 30 amp, 12v supply is. I have had no problems for 2 years. Then again I'm only running 16 strings. You may want to contact Jim at Sandevices and see what he thinks of running that through the boards. My thinking would be, run data and ground out of the board and power and ground from the PS to the injection points. That's just one point of view.

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  • 3 weeks later...

I just noticed the title and just wanted to say


Never eject power. Always inject!


I hope that was a typo, or you have some strange pixels.

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