Where to power inject

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by neo8820, Nov 27, 2013.

  1. neo8820

    neo8820 New Elf

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    Hi all,


    I'm doing a 180 degree pixel tree this year with 4 strings of ws2811 made into 4 strands each for a total of 16 strands. Each strand will have 36 pixels. The pixels would be arranged like this


    n36 n37 n108
    nx
    n1 n72 n73




    and so on...


    Where should I power inject? Should it be every 50 or should I just inject at the bottom of each stand. When I inject power in the middle of the string do I just splice the wire with the power into the +12v & grnd? Should I cut the wire in the string or leave it intact?


    I hope my question make sense. It's hard to explain this well when I'm not sure the correct terminology.
     
  2. kane

    kane Dedicated Elf

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    There's a bit of variance in pixel types, so there's no hard and fast rule - the best thing to do is to hook it up and give it a go, and see if you get any fading towards the end (or middle) of the string.. You'll find that it also depends on what you're doing with the strings - if you're never planning on having them on "full white", then it's not as much of an issue. That is usually how we would test - turn the string on all white, and then compare the light output from pixel #1 to the pixel furtherest away from your voltage input (which may be the middle of the string if injecting at the end, or would be the end of the string if not doing voltage injection) You'll find it starts to go faint or pink if it's not getting enough juice.

    I have some 12V 1804 strings that are 100 pixels long, and I find I don't need to inject power at all - I just power at the start of the string.

    But others say that they need to inject every 50 pixels for certain pixel types (probably more likely to be 5v pixels).

    In terms of how you inject - the fundamentals are that you just need to get a wire connected to the +ve and -ve wires where you are injecting (don't touch the data wire). There's no need to cut the wire, you can certainly splice, it just depends on how you'd prefer to do it. Many of us actually connect waterproof connectors at the point of injection, rather than permanently wiring the wires, as this makes things much cleaner at packup time.

    Hope that makes sense!
     
  3. garyjac1

    garyjac1 Apprentice Elf

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    I agree. I'm currently running a 180 degree ten strand tree, with folded strings of 100 pixels and powering each of the five strings of 100 with no issues (12 V). That is, five 100 pixel strings folded in halves to make 10 50 pixel strings.
     
  4. cscool36

    cscool36 Full Time Elf

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    I have a 360 dec mega tree this year with ws2801 5volt pixels folded in half.
    I inject at the start and at the end. The last 5 or so are starting to go pink and my power supply is about 3 meters away.
    Hope this helps
    Colin
     
  5. OP
    OP
    neo8820

    neo8820 New Elf

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    Thanks, this was helpful. My biggest concern though is safety. The wire on my pixels is only 20 awg. How many pixels can I safely run between injection points? My pixels are ws2811 12v .3watts per pixel.
     
  6. Robert

    Robert Apprentice Elf

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    Check out Eddies post

    http://auschristmaslighting.com/forums/index.php/topic,3668.msg31574.html?PHPSESSID=d771833f58b7873ecc2134a9c0c10a60#msg31574
     

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