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Power injection for WS2811 strip tree

Discussion in 'Power Supplies' started by Jimbo, Aug 16, 2014.

  1. Jimbo

    Jimbo Full Time Elf

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    Hi,

    I have a 4 metre high WS2811 pixel strip 2d ray tree this year. It will have 12 x4 metre strips.

    I am also using a P2. With power injection, I am intending on doing it at the bottom of the tree, so that 2 strips are connected to each other (up and then down for a total of 8 metres). SO power injection will be on strips 1,3,5,7,9 and 11 (I will be using fuses and separate power feed direct from power supply).

    Just wanting to check that this will be sufficient?
     
  2. AAH

    AAH I love blinky lights :) Community Project Designer

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    The "done" thing is 5m between injection points but it depends whether they are 5V or 12V strips and how many pixels per metre. If they are 5V then I'd be tempted to say you have no hope in hell of getting good results. With 5V pixels varying between 30 and 144 pixels per metre it depends on how many per metre you'll have as to how bad things are.
     
  3. Superman

    Superman I Have C.L.A.P and its very infectious Global Moderator

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    I would agree with Alan on that one. you have power going past the rest just do them all.
     
  4. mborg10

    mborg10 Michael Borg

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    You can never have too much power. Well sometimes you can. My first year I tried to get away with minimum power injection because I guess I didn't fully understand it. Now I plan for the worst case. I also try and use 12v because it's more forgiving with voltage drop.

    So in saying all that I'd plan to power inject at the top and it will save on headaches later.
     
  5. OP
    OP
    Jimbo

    Jimbo Full Time Elf

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    These are 12volt, 30 led per metre.

    If possible prefer to have all at bottom as didn't want them up in the air as well (aesthetically).
     
  6. Benschristmaslights

    Benschristmaslights Dedicated Elf Global Moderator Generous Elf

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    if you tape to the middle pole they will not even notice the cables
     
  7. arw01

    arw01 Full Time Elf

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    I have off an E682 17 .5m strips of 30leds a meter ink1003 with 30" of rays 4 conductor wire between each on and then another jst connector.


    With the e682 test pattern I can get 16 before the 17th will flake it out. All white would likely be shorter.


    Putting power on the end of the very last one solves all my issues instantly with strip 17.


    So in my experience, power at the end of every other one (the bottom in otherwords) with 12v strips will be hunky doree. Now I did see on one of Ray's strips he recommended against back feeding so do post what kind of strips you are using.
     
  8. ShellNZ

    ShellNZ Senior Elf

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    My tree is only 2.5m high, which is 25px (1ic per 3led) 12v stuff, same as yours I think, WS2811.

    I have 24 x 25 lengths, so I inject at the bottom of every 4th strip.
     
  9. Habbosrus

    Habbosrus New house (again) 2017

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    I have a 3mtr (1ic, 3 led) 2d ray tree x 12 strips. I have power injection at the base as you have suggested and it worked fine. You have an extra 2mtr between your injection points though. I used t type splitters for my injection points, so I was back feeding power to 2,4,6, etc. Is this what you intend to do? If so, I think it might be ok.
     
  10. fasteddy

    fasteddy I have C.L.A.P Global Moderator Generous Elf

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    Injecting at the bottom of each Z of the tree should work as long as the cable used for injection is large enough to take the current of 2 strips because you will be back feeding every even numbered strip whilst also forward feeding every odd numbered strip. You may need to use 2 power supplies for the tree and if you do just ensure the +V is not connected between the 2 supplies.
     
  11. OP
    OP
    Jimbo

    Jimbo Full Time Elf

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    Thanks everyone,

    Fast Eddy, when you say make sure you don't cross the 2 positives of the 2 power supplies, do you mean directly at the actual units?

    Based upon my calculations, (using 3 amps per strip or 0.6 Amps per metre ) the amperage of 2 strips at 4 metres will be 4.8 Amps, so figuring using 5 Amp fuses should be sufficient.

    My strips came yesterday, and already have the 2 wires on them for power injection. Am I correct is using the 3 pin connectors to connect between the strips and putting the 2 pin connectors on the power injection to run from the power supply?

    Also can I confirm that the P2 needs to have its ground wire connected the ground of the power supply? And whetehr I need to put a wire between th negatives of both power supplies?
     
  12. i13

    i13 Senior Elf

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    You don't need a wire directly connecting the negatives of the power supplies. The positives shouldn't be connected in any way. For example if you power a strip with a different power supply at each end, cut the positive line in the strip half way between them.

    Measure the current draw too. It might not be 0.6 amps per metre but remember that your measured value will be slightly under because of voltage drop across the multimeter and within the strip.
     
  13. davrus

    davrus Silent Elf

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    No !!!!!! DO NOT CONNECT the "ground" of your DC power system to the "Earth" (or "ground") of the AC Input.


    The DC power side does NOT have an "earth". The potential problems of an earth short on the AC side are why you have an RCD unit on your connection plug there.
     
  14. plasmadrive

    plasmadrive Full Time Elf

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    Couple of things..

    First off, what is an "RCD unit"?

    Secondly, Many good DC power supplies that are isolated allow for earth grounding of the neg on the DC side of the supply without issue. Some do not. Some also tell you that if you do that it may affect the EMI. Meanwell is a good example of this.
     
  15. Ɠαяєтн

    Ɠαяєтн Mae gen i C.L.A.P ei heintus iawn

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    An RCD stands for Residual Current Devices or sometimes called a safety switch. It interrupts the supply when it detects a differential between the active and neutral current of the AC supply. e.g. a ground fault. They are used to protect against electrocution.


    These are similar to the Ground Fault Interrupts GFI used in USA.


    http://en.wikipedia.org/wiki/Residual-current_device
     

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