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Thread: Will this work well for fusing and distributing power injection?

  1. #11
    Join Date
    Nov 2016
    North Vancouver, BC, Canada
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    Default Re: Will this work well for fusing and distributing power injection?

    Quote Originally Posted by DrNeutron View Post
    If you are using a PC power supply for 5V, I would be careful and read the ratings.
    PC power supplies are great for 12V power but don't usually supply much amperage for 5V.
    Almost everything on the PC that requires power uses 12V, like hard drives/dvd/fans etc etc.
    See! That's exactly why I ask this stuff I didn't decide to use it by choice. Was going with 2 x 60amp, 350 watt meanwell's to run the pixels, but I was told recently that may be pushing it a bit close. As you know (fellow Canuck), these lovely Canada Post strikes have made things annoying, and I am supposed to go live for Dec 1st. Not much time to get a new one. I have capacity on my second PSU for the injection, with the downside being a fairly long run from the 2nd floor deck down to my mini trees x 8 trees. pretty much exactly the opposite best of the best practices I've read to try and keep your PSU to delivery point as thick and short as possible. So this PC power supply was all I had on hand, tested and holds 5v voltage without turning off. To be fair, that's without load, but still, multimeter reading 5v =/- 0,1V after 10 minutes. The supply case states 5v capacity at 22amps, and the supply at 250 max. I'm a rookie with injection, but I hoped that would be able to handle 4 injection points + initial power to the first 70 pixels provided from the controller output. First 2 trees powered by e682 output, last 6 @ 35 pixels per, juiced/injected by this PC supply (if it works). Thoughts?

  2. #12
    Join Date
    Nov 2014
    Fox Valley Area, Wisconsin
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    Default Re: Will this work well for fusing and distributing power injection?

    Most folks follow the basic rule for injection: 5v ... every 50 pixels. 12v ... every 100 pixels.

    My personal experience is the variance in distribution points. I use 5v pixels everywhere except for the mega tree which is 12v. Based on my props, using 5v, some strips are more than 50 pixels and less than 100. I inject at the end of a 74 pixel run and pick up the next run ... which might only be 40 pixels.

    The idea is to keep the voltage reasonable - 4.0 to 5.0 volts ... pretty much anything in between is good. You will not see any discernible degradation in color or light level.

    I "WHITE TEST" my props to see if I can detect any significant color changing. Some strips lean a bit more blue @ full white. As long as they all appear to have the same coloring, I consider it good to go. If there are any significant differences, it is time to investigate - usually inject some power to clear that portion up.

    One thing to keep in mind ... WHITE is "ALL ON" at about 60ma per pixel. If you use a tremendous amount of white, your power supplies have to be up to the task.

    I do notice a voltage drop as the power supplies approach 80-90% of full output. I use Meanwell and Cosel units (paralleled, when necessary) with REMOTE VOLTAGE sensing in the distribution blocks.

    Also reference your "Environment". I leverage the COLD here in my area against heating. It does give me the opportunity to drive things to the maximum without too much concern for any sort of thermal runaway.

    Just like wire, the cold affects things like power supplies. Some units can be driven allot harder in very cold conditions. My tests prove this with PC power supplies also.

    I was bored one day - Put a 650 watt PC power supply into a 4 sq/ft container, NO FAN, outside and pretty much 110% FULL LOAD (5v and 12v) for 8 hours. It survived. The charted temperature results yielded @ 24F outside the container reached about 34F inside. The only air exchange was a single 2" PVC connector where the wires came through. No, I never loaded the 3.3v output because I never use it outside.

    Where I am going with all this is simply this: If your eyes cannot tell the difference at FULL WHITE, then you are good to go. The math involved is, for most, engineering for a modest application. The ONLY time I can see is for major displays where we will TEST light levels with a sophisticated meter which can detect minor output differences in a major display application.

    And --- NO --- there are no LED Police running around handing out citations for violations ;)

    The missus wants to ride!

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