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Power injection approach with 5V WS2811 strings

Discussion in 'RGB Lights - Intelligent Pixels and 3-Channel RGB' started by nutz4lights, May 9, 2013.

  1. nutz4lights

    nutz4lights Full Time Elf

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    Hey all,

    Please reference the picture below... based on some of my recent testing, I would like to do some 100 pixel WS2811 strings out of an ECG-P12R and would like to only monkey around with the beginning of the string and the end of the string (think MEGATREE where I don't want to have any wires at pixel 50 because it is up in the air 6m). I have heard people reference injecting power at the end of the string of 100 pixels. My question is, can I just order a 100 count 5V WS2811 pixel string and do as shown in the top line of the picture below? I figure, since I would be interconnecting the two 50 count strings to make a 100 count string, why not just order a 100 count string? Am I missing something? When folks have referenced taking two 50 count 5V WS2811 pixel strings and injecting power at the end, would they have done it as shown in the middle of the picture below or the bottom section of the picture below?

    [attachimg=1]

    Thanks.
     

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  2. lithgowlights

    lithgowlights Senior Elf

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    Middle picture (or in reality the first one too - same thing), but 2 things.
    1 - 5V PSU is the same one as connected to the P12R
    2 - You fuse the +5v going to the injection point at the far end.
     
  3. fasteddy

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

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    Option 1 or 2 if using the same power supply for both 50 count strings
    Option 2 if using different power supplies for each string

    Im sure you can order them as 100 if you ask Ray, issue is you may have to wait a little longer for them as they will be custom strings
     
  4. candlelight

    candlelight New Elf

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    hey eddy, when you say option 2, are you referring to the third picture (the one at the bottom?)

    and am I understanding correctly, that if your only using one power supply, its ok to connect power at both ends and leave them connected in the middle?
    In the past, regardless of how many psu's, I've always attached power at both ends and cut the power in the middle...
     
  5. fasteddy

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

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    The first 2 drawings are effectively the same thing. The last drawing does not have the +V connected together and would be used if he was supplying both strings with a different power supplies
     
  6. kane

    kane Dedicated Elf

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    Eddy, I think he's referring to the following - where I assume you meant to say "Option 3 if using different power supplies for each string"


     
  7. OP
    OP
    nutz4lights

    nutz4lights Full Time Elf

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    Thanks everybody! In my mind, option 1 and 2 were the same thing (I am using the same power supply), but my mind is off from reality sometimes... I wanted to make sure there wasn't an issue leaving the voltage wire connected in the middle.. I guess because those pixels are all in parallel between the +V and ground, it doesn't matter if the voltage its connected at both ends.

    In regards to the strings taking longer to arrive, I am planning on ordering them with connectors. In other words, they're already going to be custom.

    Instead of separate fusing, is there any reason that I can't have the end of string +V and ground screwed into the appropriate output of the P12R as long as I don't draw to much current from that output?
     
  8. rvenegas

    rvenegas Apprentice Elf

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    Nice topic, I was having same doubts. However the PSU has 3 outputs, that means I can power inject 3x100 strings with same PSU..right?
     
  9. kane

    kane Dedicated Elf

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    PSUs don't tend to have three "outputs" as such, they may have three screw terminals, but the number of these doesn't dictate how many you can connect - you could connect 5 items to a single pair of terminals.

    The key thing to look at is the power draw of the lights, compared to your PSU. So if your strings are consuming 15w per 50, then it's only 90w for your 3 strings of 100.

    Most of us seem to only load up to 80-90%, so if you have a 350w PSU, you may only want to load up to 270w, but this would give you 900 lights (18 strings of 50)

    hope that make sense!
     
  10. rvenegas

    rvenegas Apprentice Elf

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    Of course it does!!!! i get it now.
     

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