1. New to Christmas lighting? Get started with the AusChristmasLighting 101 Manual:
    auschristmaslighting.com/wiki/AusChristmasLighting-101

power injection confusion

Discussion in 'Backyard BBQ' started by lizardking, May 9, 2015.

  1. lizardking

    lizardking IT IS STILL ALL BENS FAULT

    Joined:
    Dec 26, 2014
    Messages:
    416
    Likes Received:
    0
    Location:
    Gold Coast
    Find Me On:
    hi all I am using the P12S with 2 universes per output and will be running 6 strings of 50 pixels per output which will be 18 amps per output i am running 24 strings so 4 outputs, do i have to run the strings 2 strings from one side of the board and 2 strings from the other side of the board i have 1 psu per side of the p12s at 350w @60amps plus one more psu for power injection so running 100 pixels of power out of each output of the p12s will be 6 amps at full white so if i power the strings this way will i be correct
    1. data and power to the strings 1 and 2
    2. data to strings 3,4,5,6,
    3. power to strings 3,4,5,6 from the 3rd psu which will be 12 amps over all the 4 strings
    4.can i run just data from the p12s or do i need to run power and data to the first string at least from the p12s


    really confused
     
  2. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    775
    Likes Received:
    6
    You can get the data from the controller without powering anything via the controller if you want to. All that needs to be continuous along the entire length of the strings is the data line(s) and the negative. You don't have to connect the positive output from the controller if you don't want to.

    The pixels will be powered from whichever supply their positive is connected to and that can be through the controller. Never connect the positive between two or more power supplies and don't create a connection between a power supply and a positive output of the controller (you might get away with this if you use the same power supply for the first injection point and to power the controller but I don't see a good reason to try).

    Basically you just need to cut the positive line of the pixels somewhere between each power supply and between the first injection point and controller.

    I presume you know the p12S can handle that current because I don't know.

    Remember to actually measure the current draw because it might not match the value stated on the seller's listing.
     
  3. damo1271

    damo1271 Full Time Elf Generous Elf

    Joined:
    Oct 12, 2011
    Messages:
    193
    Likes Received:
    3
    Location:
    Adelaide
    Find Me On:
    I currently use 9 outputs on the P12, each output driving 160 pixels (approx 1 universe).

    I use 9x 40A@5V power supplies, one for each output/universe.
    (I find the cheap Chinese power supplies I have will NEVER drive their stated current/voltage capacity and I always halve it to be safe. It also gives me some spare capacity if a PSU dies.)

    One PSU supplies power to the P12 in addition to the pixels.
    I operate the P12 with the 5V power supplied to the P12X board (both power connectors) and the terminals on K1 bridged: +V to +5V.
    The P12 does not supply any power to my pixel strings, only data and ground signals are connected from the P12 to the pixel strings.

    All the PSU grounds are connected together. With each power supply, the power cable (ground and +5V) runs from the PSU to a single pixel string. Power is injected along the pixel string every 50 pixels from the same power supply. Ie PSU1 supplies power to string 1 and the injection points along that string. PSU supplies string2 and the injection points along that string, and so on.

    The data signals (Data and ground) run from the P12 to the pixel string.
    The grounds from the data cable and the PSU cable are connected together at the pixel string.

    No connections are made in any positive leads between power supplies.

    Hopefully the attached pic shows more detail.
     

    Attached Files:

  4. i13

    i13 Senior Elf

    Joined:
    Jul 5, 2013
    Messages:
    775
    Likes Received:
    6
    damo1271 thanks for the clear drawing. Doesn't it still work fine without the direct connection you've drawn between the negative power supply outputs? Lizardking you'll find you don't need this if you power one string from multiple supplies because the negatives are already connected through the pixel strings. Always cut the positive line in the strings between each power supply.
     
  5. damo1271

    damo1271 Full Time Elf Generous Elf

    Joined:
    Oct 12, 2011
    Messages:
    193
    Likes Received:
    3
    Location:
    Adelaide
    Find Me On:
    I use lighter cables for the data (alarm cable) vs the power (24/0.20) so there would be a significant voltage drop in the alarm cable given the current being carried.
    The power cables are figure 8 so I simply use both wires.

    Admittedly I don't connect the data ground to the pixels on every string, so yes it works without the second connection. By tying the grounds at the pixel string I can be sure that the ground references are the same in both the data and the power cables. The ground loop created doesn't seem to affect the operation, and I actually think I get less flickering of pixels with the grounds tied together at the pixel end as well.

    Bottom line, as you have pointed out, is to never connect the positive power wires between different supplies.
     

Share This Page