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760peewee
01-31-2017, 10:44 PM
I am making a matrix with 650 pixels. I will be injecting power every 100 pixels. I will be using 2 350w power supplies. When using a tee to inject power, when you are not moving to the next controller, and using a tee wired like the one in the picture (from diyledexpress) would I just hook up both positive leads to the same output on my distro board? Thanks!

https://uploads.tapatalk-cdn.com/20170201/967df5a520e1d95e2034bd6e50b55494.jpg


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pmiller
02-01-2017, 12:47 AM
Note that the picture is correct but also is incorrect. The positive led at the injection point is yellow. It's confusing and I'm not a big fan of the wire colors being different but that is the case. The yellow positive wire goes to the positive brown wire. Here's a pic that did did a few months ago to better understand the wire colors and where they go. Yellow data (as you can see that isn't always the case), blue -12v and brown +12v. You may think by connection the browns that you would get power but it won't work. Had me fooled for awhile until I used a meter to check the connections. https://uploads.tapatalk-cdn.com/20170201/836a4d267190bf3761c709eb201ca113.jpg

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760peewee
02-01-2017, 12:49 AM
I think the question is wether or not to back power the previous string... any comments?


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pmiller
02-01-2017, 01:02 AM
I think the question is wether or not to back power the previous string... any comments?


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That depends on your pixel voltage and how many in a string. If your using 100 pixel 5 volt strings then yes, you need to inject at the end. If using 100 pixel strings of 12 volt pixels then no, you don't need too. That's where the yellow wire connected to the brown wire comes in when you need to inject at the beginning of a string. You can use one output to feed a 16 string tree but you need to inject at the beginning for 100 pixels at 12 volts and both ends of a 100 pixel string at 5 volts.

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Kensington
02-01-2017, 07:59 AM
On 12v pixels I always "back power". Cuts my injection points in half, since there's an injection point every 200 pixels rather than 100 pixels.

When you say "connect both positive leads to the same output on my distro board" do you mean connect the V+ leads from the string and the V+ lead from the power injection cable to the same distro board? If yes, the the answer is "it depends". You can back power all day long without any modifications PROVIDED THAT you are using a single power supply. Once you add a second power supply, you need to "isolate" the V+ lines so V+ from PS1 and V+ from PS2 do not connect. To do this on a string controlled by a single controller output, I cut the tee on the side that connects to the upstream pixels (left side, in my case), clip the V+ lead short and double wrap it with shrink tube, then solder and waterproof the ground and data lines and cover the cut with more waterproofing and heat shrink.

If you don't want to cut tees and you have channels to spare, you can simply divide the matrix between two controller ports, disconnect the v+ line for the second string at the controller, and inject power at the beginning of the second string.