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Noob Questions

Discussion in '101 Display Basics' started by Cathelest, Jun 11, 2018.

  1. Cathelest

    Cathelest New Elf Generous Elf

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    Hello, I am sorry for the noob questions,

    I currently have a rasp pi with smartalec's pi hat,
    I got this as a entry level controller to play with, but will likely get a falcon f16 eventually,

    Last year i just put a 5 meter strip up, just as a test, and had a 3 meter run of cable running to the start,
    I did not have a cable connected to the end, and as such ofcorse it glitched on full power due to needing power at the end
    i presume,

    This year i am looking to
    I am looking to do just a gutter outline on the front of a house, and possibly some leaping arches,
    I have bought a bunch of pigtails and have some a roll 5 core security wire,

    The front of the house is about 18 meters wide, and i am only looking to do the guttering for the moment,

    Am i best to put the controller in the middle of the house, and then have about 10 meters to each end of the house,
    And i presume i am best to run the same length cable to all injection points in between, even knowing theyre closer,

    I guess i can use the 5 core security cable and pigtails, or maybe i should buy a bunch of the premade ray wu extensions, Thoughts?

    Many thanks
    Ben
     
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    Cathelest

    Cathelest New Elf Generous Elf

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  3. djgra79

    djgra79 My name is Graham & I love flashing lights! Generous Elf

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    HI Ben.
    Data for pixels needs to travel in 1 direction and in series. The Pi-hat only has 2 outputs of data, so if you have the pi and pihat in the centre, then you could have 1 output per side going in opposite directions to the ends of the gutters.
    Otherwise if you have the pihat at one end, the entire length of gutters can be 1 output, freeing up the 2nd output for possibly another element.

    Then there is power to consider. The basic rule of thumb is that 5v lights need power injection every 50(ish) pixles, and 12v every 100(ish) pixels.
    5core security cable cable be used for both data and power - I use 4 core myself and have a separate cable for power injection, twisting 2 cores together for pos and 2 for neg. I also use it for data with 1 core for data and 2-3 cores for ground/neg as this ensures a stronger signal.
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    Ok great, many thanks for the reply,

    I am using 12v strip, which I beleive is 300 led/5m (60led per metre)

    But the pixels are in groups of 3 I think,
    Should I be ok to just inject between strips? Or do you think I will need to cut it up?
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    Does anyone have wiring layouts they use for the shows, so I can get an idea of how long people's runs are and where they position their controller and PSU/(s)

    Many thanks
     
  6. djgra79

    djgra79 My name is Graham & I love flashing lights! Generous Elf

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    That sounds like the same strip I have on my roof and gutters. Every meter is 10 pixels (a group of 3 LEDs is considered 1 pixel - more info HERE)
    SO if the controller is in the middle and extending approx 10m either direction, I think you could power them at the start of each string and they could be enough. Worst case if the ends look a little dull or discoloured, particularly on white, then just power inject at the ends also.
     
  7. djgra79

    djgra79 My name is Graham & I love flashing lights! Generous Elf

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    Here's what my roof strip and garage outline looks like.

    View: https://www.dropbox.com/s/k42xqgye2myitsx/Roof%20PI.jpg?dl=0

    The roof strip start in the far right corner and goes along the gutters, up towards the peak on the left, across the top then back down the right hand side.
    The yellow boxes indicate the power injection point and length of cable going to that point. For example, the first box says "5M PI, A 2M" which translates to 5meter power injection cable, then section A which is 2M of strip.
     
  8. keithsw1111

    keithsw1111 Full Time Elf

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    Don’t cut your strip. Just power inject at both ends.
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    Many thanks Graham, your awesome, exactly what I needed, helps alot,

    With the different lengths of power, from 5m to upto 19m, how to you combat voltage drop on the 19m run? Is it an issue?
     
  10. djgra79

    djgra79 My name is Graham & I love flashing lights! Generous Elf

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    Its not an issue, probably because I have slightly "over-injected" which is not a bad thing. If you count I've injected around every 80 pixels, I could possibly have gone more pixels as power runs both directions, so if you inject at the start and at the end of 100 pixels it will be fine.
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    Many thanks, guess I shall grab some more strips and start,

    Do you use pigtails?
    If so do u just put a second pigtail in between strips to power inject or do u use the t connector pigtail, or do you hard wire, or ?
     
  12. djgra79

    djgra79 My name is Graham & I love flashing lights! Generous Elf

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    Go to 1min 5secs in my behind the scenes video:
    https://auschristmaslighting.com/media/evans-central-2017-behind-the-scenes.507/
    You can see the black T-Piece that I use for power injection. Data comes in from controller 3 pin side through to strip, then the 2 pin underneath is the power from PSU.
    https://www.aliexpress.com/store/pr...215.html?spm=2114.12010615.0.0.562a29d6wKpgWU
    Make sure to check polarity on the pins first before use, as some people have had some pins swapped which will cause issues.
    I use these all over my display for my power injection.
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    Oh wow, penny just dropped lol, I have seen that video recently a few times, and a bunch of your show ones, very impressive,
    (I actually found your first video when searching for air seeder hose to make arches lol,_
    I shal start making a shopping list i think, many thanks, Ben
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    I am getting my shopping list together,

    With the wiring,
    I already have a roll of 6 core security cable,

    The strands are quite thin, not sure of the awg,
    And I know I could use 3 for 12v and 3 for ground (for injections) but should I bother with it or am I better to buy a bunch of the ray Wu pigtail extension cables,
    It seems to be the norm now?
     
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    Cathelest

    Cathelest New Elf Generous Elf

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    I have received a bunch of things today,

    I am still using a rasbpi3 with smartalecs 2 channel pi hat,

    I have connected 2 of raywu pigtails to a 12v PSU (one at start, and second at end just for power and ground, data not connected at end obviously)
    When I run the lights (bunch of 100 nodes) strait off the pigtails they work fine,

    If i put in a 3 meter extension they start glitching out,
    (Brightness is fine but just start glitching)
    I am presuming I need to grab some null pixels or ???
    Advice??
    Does data normally degrade that much over a 3 meter run or is the pi hats output perhaps too week and a null needs to be added before extension?

    Thanks Ben
     

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