Demystifying power injection for a newbie

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by ievolve, Nov 11, 2013.

  1. ievolve

    ievolve New Elf

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    Hey Guys, total newbie here. Trying to learn as much as possible and wrap my head around this stuff.


    With regards to power injection, I have seem videos online demonstrating what happens when you do not have sufficient power to feed the strand, IE, dim/nonfunctional lights on the end of the chain.


    I have also seen it mentioned that you should plan on power injection every 40 to 70 pixels.


    Here is where I am drawing a disconnect. I found a cool 5m of strip lights, problem is there are 300 pixels on the strip. If my math is right, I would need to inject power about 6 or 7 different places along that 5m strip?? Seems pretty excessive. I know there is something I must be missing because I have seen videos of people plugging that whole reel in without any troubles (or power injection) Can some clarify this for me?


    FYI, I've got my eye on the SanDevices E682 package that has the power supply and everything, hoping to make my first jump into this stuff as pain free and expandable as possible. But the thought of having to re-inject power every meter has me scared. At that rate I'd have more power lines than lights!
     
  2. AAH

    AAH I love blinky lights :) Community Project Designer

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    Have you got a link to that specific strip as 300 pixels in 5m is a mega high number. Depending on how it is specified and whether it is 5V or 12V strip there can be a number of leds per pixel. As a super general rule of thumb you can get away with 5m of pretty well any strip without needing to do anything. You may need to inject power at the far end if things look a bit pink when all the pixels are on white.
     
  3. kane

    kane Dedicated Elf

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    I'm guessing it's a 60led/metre strip, like this one:
    http://www.aliexpress.com/store/product/4m-WS2811-LED-digital-strip-60leds-m-with-60pcs-WS2811-built-in-the-5050-smd-rgb/701799_638374848.html

    I've used some of these in my spinners, but can easily inject power every 1.2m, so this is what I've done - I don't think it'd be necessary though.

    If it's supplied as a 5m strip, you would think it should be fine, but you'll never know until you hook it up and check it out! (maybe someone here has tried it out?)
     
  4. neilric99

    neilric99 Full Time Elf

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    with the 5V pixels in the strip (I use the rigid strip) I found that it is necessary to power inject very couple of meters (or both ends on a 4M strip) and that was only 32 leds/meter. I am using 4 * 42 node lengths and into the 2nd section I notice color issues when mixing colours, especially white. So I am injecting every 2 sections right now to be sure.
    Power Injection is just a fact of life when using 5V strip.
     
  5. OP
    OP
    ievolve

    ievolve New Elf

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    I'm just trying to plan a little before I go an buy a bunch of supplies. Perhaps the first order will just be a bunch of various different types to play with. I certainly don't need something as dense as 60/meter, that was just the one I ran into first (see the ali express link above) I do like the lower profile strip form factor, wish they had less density per meter so I just would have no concern about power injection.


    Perhaps I am over reacting on the power injection thing. Is there some way to daisy chain it? I imagine there are some diagrams or pics of how people have done it, are they just all home runs from a central box? If a guy had a hundred meters of lights and needed a hundred different power injection points where in the world would be plug them all in?
     
  6. mborg10

    mborg10 Michael Borg

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    If your worried about too much power injection have a look at 12v. Voltage drop is more forgiving than 5v.
     
  7. AlexB

    AlexB New Elf

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    I have this year taken my first dive into RGB strip this year - and have just finished installing 25 metres of 12v WS2811 'dream' strip.


    I chose 12v because of the reduced concerns about voltage drop. When they arrived, I connected all 5 strips (5 metres each) and didn't have any loss in colour or detail until strip number 4.


    As I was wiring them up to conduit in 5 metre lengths anyway, I was advised (i think by AAH) that running two lines of 14/020 power injection would be the best bet.
    Since I was wiring it up anyway, I just ran 2 x 5 metre lengths inside the conduit, soldered them onto the pigtail connector, and joined it with the power cables from the strip, and heat shrinked it all together... so I'm basically injecting at the beginning and end of every strip, and there is absolutely no issue with voltage drop anywhere along the 25 metre length.


    The advice to stick with 12v is sound advice... I'd stick with it.
     

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