Just checking my P2 setup to avoid the magic smoke

Discussion in 'EthConGateway by Joshua 1 Systems' started by logandc99, May 29, 2014.

  1. logandc99

    logandc99 Dedicated Elf

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    Just setting up my P2s and wanted to make sure I'm jumpered up properly for power.
    I'll be running 12v Ws2811 pixels with it.
    From the videos and PDFs I've looked at I presume I just put the jumpers on k3 as 1-2,3-4 and leave the jumpers off the J1, J2 and k2 as per the photo below.
    Presume then it's safe to connect my 12v power supply to the P2 without causing any damage.

    The other thing I want to check is that I presume I should not try to power the pixels via the board ( hence leaving J1 and J2 un-jumpered ( or open) as the board can only handle 1amp and a 5m strip light on White would pull 3amps and damage the board ( right?... I hope). Therefore I would power the pixel strips via power injection direct from the power supply.
    If this is correct do I power inject at the beginning of the first strip and then between every subsequent strip? If so is it fine to use one of Rays 3pin T shaped cords where the middle is two core for power injection and put this between the P2 and the first pixel strip or is there a risk of back feeding power back to the P2 and damaging it ( or is this a nonsense notion and too much will not back feed into the P2)?

    Sorry if the questions sound dumb to the educated but this is my first time using a p2 and I really don't want to blow it up. I used the p12s last year but that board can feed power directly from the board to the pixels and has fuses etc for protection which the P2 does not.

    [​IMG]
     
  2. Benschristmaslights

    Benschristmaslights Dedicated Elf Global Moderator Generous Elf

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    logan your correct in what your saying I never run power for the pixels off my p2. I always run power direct to the pixels with a fuse inline. I also put a fuse inline for the p2 power.if the pixel power is not connected to your p2 you have no worry of feedback.
     
  3. ShellNZ

    ShellNZ Senior Elf

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    Um yeh, highly recommend that and double checking +/- lines :p

    Assuming you are using the 3led per IC 2811 strip, I only power injected at the start, then between 2/3 strip then at the end (or if I was carrying on attaching more rolls then every 2nd roll).
     
  4. OP
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    logandc99

    logandc99 Dedicated Elf

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    Yes primarily I will be using 3led per IC 2811 strip with the P2 but also some of Ray's Stars.
    http://www.aliexpress.com/item/DC12V-WS2811-star-type-pixel-module-6pcs-5050-SMD-rgb-led-inside-1-44W-IP68-ONE/1602954057.html

    Ok, so I guess then I shouldn't use Rays T shaped cable with the two pin power in the centre between the P2 and strip as that will flow power back to the P2. So just to confirm, do I just run just the one data line from the P2 out to the pixels and feed the V+ and V- direct to the pixels from the power supply to ensure that there is no power to feed back from the pixels.
    [​IMG]

    Or does the ground also need to be connected between the P2 and pixels?
    I have left the in line fuses out of the diagram for simplicity.
     
  5. mborg10

    mborg10 Michael Borg

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    Last year with the stars I had 96. I injected at star 30 and at the end, my stars are 12v ws2811
     
  6. BundyRoy

    BundyRoy Senior Elf

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    I asked that question the other day and if my understanding is correct then you should connect the ground from the lights back to the P2 as well. I would wait to get confirmation from someone more knowledgeable though before doing anything.
     
  7. OP
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    logandc99

    logandc99 Dedicated Elf

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    Yes I was wondering if that was the case as there has been much talk about flickering lights and other odd pixel behaviour if grounds are not connected up. Although I had thought that was primarily to do with using more than one power supply to feed pixel runs that are connected and that the grounds of the power supplies needed to be made common ...... so wasn't sure if that also applied to the P2.
    Thanks. I will await confirmation as you suggest.
     
  8. BundyRoy

    BundyRoy Senior Elf

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    One other thing I just thought of. Do you need in line fuses in the power lines to both the lights and the controller. I don't know much about the P2. Does it have/need a fuse to protect the board circuit. Again I am a greenhorn. You're probably all over this issue, just asking as much for my benefit as anything.
     
  9. OP
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    logandc99

    logandc99 Dedicated Elf

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    It doesn't have any fuses. As Ben ( Yagoona Lights) suggested, putting an in line fuse between the board and P2 would be a good idea to protect the board. Also between the power supply and lights to protect the lights.

    Hopefully someone can give confirmation that my wiring diagram is correct (or wrong as the case may be).
     
  10. OP
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    logandc99

    logandc99 Dedicated Elf

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    Thanks. Good to know that I don't need to inject as often as I thought.
     
  11. OP
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    logandc99

    logandc99 Dedicated Elf

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    Ok, so looking at the video again on how to setup the P2 that Andy Harrison did ( extremely helpful by the way) it looks like my wiring setup is close but I do need to hook the ground from the p2 output end back to the ground of the power supply. In the video he says he is not sure if that is a must or not but it works anyway. Is it a must or does it work ok without?

    Here is my revised setup drawing based in the video

    [​IMG]

    Oh and two more dumb questions
    1), do I use a 1or 2 amp fuse between the power supply and the P2. I understand the p2 is only supposed to take a max of 1amp so presume 1 amp would be best?
    And
    2) between the power supply and lights, a 3amp fuse or slightly higher since a 5 m strip will pull 3amps when on full white. I don't want the fuse to blow every time I go white so presume it should be higher than 3 but how much higher to ensure the lights are protected.
     
  12. BundyRoy

    BundyRoy Senior Elf

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    Your diagram matches my understanding. From my understanding you could also take the v- from the P2 to the grd on the strip if this is shorter/easier to do as it ends up being exactly the same circuit as you have drawn as all the v- is linked anyway.

    I am also interested in what size fuses to use.
     
  13. ԆцряєсϮ

    ԆцряєсϮ Senior Elf

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    Your fuse size between your power supply and strip will depend on a few things.
    The fuses are there to protect the cable supplying the strip so you need to know:
    1) the current carrying capacity of the cable your using
    2) the current that will be travelling along that cable
    Your fuse size needs to be somewhere between the 2.
    ie lower than no 1 and Higher than No 2.


    For no 1 you can get that from google or the wiki
    For no 2 you'll have to work that out as you haven't said how many strips etc. you intend to run.
    Also how you intend on feeding them.
    an example - If your only running 1 strip then No 2 = 3A, if your running 3 strips end to end with only 1 feed then No 2 = 9A (Add Currents together in a series circuit)


    If your running say 4 strips (with injection after the second strip)
    Then assuming you use the same size feed cable and the feeds are roughly the same length then each cable will carry roughly the same load (6A)
    so as you can see there are a few variables that you need to consider.


    Hope that makes sense
     
  14. OP
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    logandc99

    logandc99 Dedicated Elf

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    Yes that all makes sense and has been a lot of help, thanks.
     
  15. davrus

    davrus Silent Elf

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    Just remember that the capacity of the -V cable equals that of the +V cable. If you are doing power injection (thus multiple cables), you need equal capacity on the -V cable(s) to get the power back.
     

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