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How many 12v LED bullets can effectively be strung together


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Q: As a best practice, how many LED pixels (Nodes/bullets) can I properly string together on a single data run from my controller for a large RGB prop before I start to see data signal latency?       Power isn't an issue as we're re-injecting 12vdc every 75 nodes.   (Using 12v WS2811's.)

 

We've been dark for quite a while, and now we're digging our stuff back out to go live this fall.   We made a lot of newbie errors over the years and now we're trying to rewire, reorganize and fix our errors of the past when we were a little more in the rushed "See what works" mode.   Due to lack of experience, we were very inefficient with our controller planning, and now we're trying to consolidate a lot of very underutilized controllers and runs to minimize hardware, cords and setup time.  i.e. Not knowing better at the time, we ran a line back to the controller for every 50 pixels which doesn't seem to be the most effective idea.

  Thanks!

  

https://www.youtube.com/watch?v=vjjKuEPe8Cw&list=PLyi_DAPKiGs1gnQGcCGFeDERISv0L-I2H&index=4

  

Edited by Bizywk
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That largely depends on the controllers.  Different controllers have different possible pixel counts.  Also with high counts, the refresh rate goes down.

The longest strings I am currently running is 100 pixels.  However I don't like running long strings because WHEN (not IF) a pixel fails in a mode where it leave the remainder of that string dark (or worse, full white), far less of the display is affected.  BTW, my shortest strings are eight and nine pixels (OK, they are each grouped of 11 pixels, so it is really 88 and 99 pixels, but logically, it is eight and nine pixels).

 

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5 minutes ago, KYHI said:

Question - Is that not what a Null Pixel does (Boost the Data Signal) ??

Yes, a null pixel is used when there is a long distance between pixels. The data signal deteriorates the longer it has to travel between pixels, a null pixel or any other pixel will regenerate the signal and send it down the line to the next pixel. The next pixel reads the data, takes what belongs to it, regenerates the signal and sends it along. As long as there are pixels it could possibly keep going that is why voltage drop is usually the main concern in long runs and why PI is needed.

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48 minutes ago, KYHI said:

Question - Is that not what a Null Pixel does (Boost the Data Signal) ??

Repeats, as in squares it back up. Data is a square wave (1 or 0 ). Voltage drop ON THE SIGNAL (data) line is not usually the issue.

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Every controller like a pixie does not support a null pixel.

Also a pixie controller can push 170 and in most cases as in what my friend Jim said it will depend on the situation will not need PI

Sounds cool though, doesn’t it? 
 

With all of the pixels controllers I run I have 0- none power injection. My pixie controllers all test at 170 since that was what they were first touted to run even during beta they tested good.

After beta my longest run is 156 with 120’ of extension between controller and first pixel.

BLUF- test based on your scenario to find out for sure. Pixel types and mfgs fit in to the equation as well.

JR

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Thanks for the input guys!    It really is nice to have a great group of experienced guys to reach out to for a fast response when needed.

I guess you guys gave me a lot to think about as we head back to the drawing board. 

Biz

 

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20 hours ago, dibblejr said:

Every controller like a pixie does not support a null pixel.

Sure it will - but you have to sequence it - as opposed to telling the controller to insert it for you.

Let's say for the discussion, you have 150 pixels evenly divided on three windows and because of distance you need a null pixel after pixel 100 (after the second window - so you will actually need 151 pixels when you include the null pixel).  When you set up your preview (in S5) or channel config (earlier versions), window 1 becomes channels 1 - 150 (pixels 1 - 50), window 2 becomes channels 151 - 300 (pixels 51 - 100), the "null pixel" becomes channels 301 - 303 (pixel 101), and window 3 becomes channels 304 - 453 (pixels 102 - 151).

 

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4 hours ago, k6ccc said:

Have your tried the therory? 
Originally the pixies did not recognize a hard wired null pixel. I have a bunch I have tried.

However other than just not sequencing certain pixels when not needed I have not attempted to wast my time on sequencing one in S5
 

I simply don’t needed extra data boost, never had But did try it during beta and in S4 since we beta tested before s5.

JR

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Sure.  A null pixel is no different than any other pixel.  The fact that we will never send any lighting commands does not matter.

OK, maybe the pixel used is one that has a dead color that was pulled out of some other string...

 

 

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