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Thread: Thoughts on injection needs for 5v bullet runs

  1. #1
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    Default Thoughts on injection needs for 5v bullet runs

    So, this isn't a post asking how to power inject, but rather, seeking feedback from your collective experiences from a design and appearance viewpoint. Up front, I already have all 5v ws2811 bullets and power supplies for stock, so at least for this year, I'm not going to switch to 12v unless necessary. I already did a display last year with 5v pixels, and discovered all the extra power injection work and considerations involved. But it worked where I used them, because a mega tree with mounting strips, I can power inject behind the strips so it's not ugly. Mini trees, injection points more visible, but not too many, so it looks ok. This year, I'm also doing 4 windows (4' x 30" ea), 2 door frames, and I was planning on running a line on the face of my roof peak, which then follows the trim and then goes down to ground outlining the house corner. Easier to visualize, I'll attach a pic. I'll be running 3" spacing, so would certainly need Injection. With these clean outlines, it would look like crap to have a bunch of extra wires randomly cutting across the siding to connect on the windows and doors, but it's the gable and trim that concerns me more. It's quite high, not a great work area, and I'm not entirely sure how to avoid it being an eyesore but also placement of power source and cable runs.... Any suggestions? Of course 12v would allow longer runs without injection, but all my stock is currently 5v. See below

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    Default Re: Thoughts on injection needs for 5v bullet runs


  3. #3
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    Default Re: Thoughts on injection needs for 5v bullet runs

    Daytime view (picture no leaves blocking house). The peak is actually pretty difficult to reach safely tooScreenshot_20190912-002005_Gallery.jpg

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    Default Re: Thoughts on injection needs for 5v bullet runs

    What I commonly see here is a strict adherence to "I must power inject every 'put your number here' pixels". Take another look at your windows and think "If I run a power line up the left side of the window then I can inject at the start of every horizontal string and not worry about exactly how many pixels are in that horizontal string. Since all of the strings on a given window are powered by a single PSU, I don't need to cut the V+ wires anywhere on the window (you can but I don't). This does result in power loops but I have not had a single instance of power loops over such short distances causing any sort of issues. In essence, A window with top/mid/bottom/left/right strings has three injection points on the left side that provide enough power to run the entire window. The left side is over injected but that does not hurt anything.

    As for runs between windows, those get tucked into the space between the gutters and the house and drop down to the window with the data line at a single point. I also tend to run 14V in my main feed lines with buck converters at each injection point.


    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  5. #5
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    Default Re: Thoughts on injection needs for 5v bullet runs

    Quote Originally Posted by MartinMueller2003 View Post
    What I commonly see here is a strict adherence to "I must power inject every 'put your number here' pixels". Take another look at your windows and think "If I run a power line up the left side of the window then I can inject at the start of every horizontal string and not worry about exactly how many pixels are in that horizontal string. Since all of the strings on a given window are powered by a single PSU, I don't need to cut the V+ wires anywhere on the window (you can but I don't). This does result in power loops but I have not had a single instance of power loops over such short distances causing any sort of issues. In essence, A window with top/mid/bottom/left/right strings has three injection points on the left side that provide enough power to run the entire window. The left side is over injected but that does not hurt anything.

    As for runs between windows, those get tucked into the space between the gutters and the house and drop down to the window with the data line at a single point. I also tend to run 14V in my main feed lines with buck converters at each injection point.
    Just for my own curiosity, do you use 3a or 5a buck converters?
    Phil

  6. #6
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    Default Re: Thoughts on injection needs for 5v bullet runs

    Mostly 3A. I also inject every 25 pixels (or less). I am way over engineered.


    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  7. #7
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    Default Re: Thoughts on injection needs for 5v bullet runs

    Quote Originally Posted by MartinMueller2003 View Post
    What I commonly see here is a strict adherence to "I must power inject every 'put your number here' pixels". Take another look at your windows and think "If I run a power line up the left side of the window then I can inject at the start of every horizontal string and not worry about exactly how many pixels are in that horizontal string. Since all of the strings on a given window are powered by a single PSU, I don't need to cut the V+ wires anywhere on the window (you can but I don't). This does result in power loops but I have not had a single instance of power loops over such short distances causing any sort of issues. In essence, A window with top/mid/bottom/left/right strings has three injection points on the left side that provide enough power to run the entire window. The left side is over injected but that does not hurt anything.

    As for runs between windows, those get tucked into the space between the gutters and the house and drop down to the window with the data line at a single point. I also tend to run 14V in my main feed lines with buck converters at each injection point.
    That's some good thinking Martin. How about that high line that runs along the roof peak and then left before dropping and outlining the left edge?

  8. #8
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    Default Re: Thoughts on injection needs for 5v bullet runs

    Cut the V+ in the corner and power the left edge from a different supply or snake a big fat cable from the power supply (I assume on the balcony) down the post and over to the bottom corner.

  9. #9
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    Default Re: Thoughts on injection needs for 5v bullet runs

    By my count, you don’t really “need” to power inject anywhere other than the start or end of the windows. You’re at 52 pixels on each window, so you don’t have to cut your lines to add power on each window. If you’re daisy chaining the windows to other props, you’d just zip tie a power feed to the same anchor point as your data wire.

    As for the roofline, I’d probably run the power lines over the top of the gable to the right side, then inject at the end of the left side of the gable where the roofline goes back toward the house, then inject at the bottom of the left vertical outline. If that whole line is 50 feet, that’s only 200 pixels at 3” spacing. You can pull that off with three injection points of the same PSU—beginning of the strand gets you 50-ish, middle of the strand gets you 50-ish in both directions (100 pixels powered total), and the end of the strand gets you another 50. No one is going to see the cables running on the top of the roof, and the one drop in the middle of the strand will hardly be noticeable.

    Or just run cables wherever you want and paint them to match the house.

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