Results 1 to 7 of 7

Thread: Power Supply Equation

  1. #1
    Join Date
    Jan 2019
    Location
    Honokaa, HI
    Posts
    14
    Post Thanks / Like

    Default Power Supply Equation

    Aloha,
    I have been looking (and failing) for the equations to figure out how many pixels can be powered per power supply. I see people saying it's like 530 pixels for a 350W PS, but I want to understand where that number comes from. Does it change based on brightness? I'm sure this has been asked before so sorry that I couldn't find it.
    Also I realize this is really general with no specifics and that's because I'm looking for the generalities. I plan on running 5V and 12V in my designs in the future.
    Do we need to account for current draw from a controller board as well or are they generally negligible.
    If you really want my specifics I have a single 12V 350W PS, 350 12V bullets, 18ga wire.
    Mahalo,
    Sam

  2. #2
    Join Date
    Dec 2017
    Location
    Canton, OH
    Posts
    4
    Post Thanks / Like

    Default Re: Power Supply Equation

    The general rule of thumb is 0.3 watts per pixel at full white brightness... multiply that by number of pixels and voltage to get the required watts at max load... and then factor in about 20% more for overhead and controller power...

    There are other factors that apply.. but that should get you in the ballpark/a basic understanding of it

    Sent from my SM-G975U using Tapatalk
    CantonSouthChristmas

  3. #3
    Join Date
    Jan 2017
    Posts
    84
    Post Thanks / Like

    Default Power Supply Equation

    Yes power does correlate to brightness. The controller itself draws minimal power if not powering pixels through it. As for 350 pixels the power supply should do that. You’re getting close if 12v. But are all 350 hooked together in a string or multiple strings equaling 350. That will make a difference on how you approach it.


    Sent from my iPhone using Tapatalk

  4. #4
    Join Date
    Sep 2007
    Location
    Valley Center, Ks
    Posts
    410
    Post Thanks / Like

    Default Power Supply Equation

    From a purely electrical design standpoint. You would calculate the power supply capacity as follows:

    Current (amps) = Power (watts) / Voltage

    350/12 = 29.17 amps

    So assuming you have typical pixels like DIYLEDExpress sells then each pixel will draw 50mA at full brightness and white color. 50mA = 0.05A

    So for 10% spare capacity

    29.17*0.9/0.05 = 525 pixels

    Find out the current draw of your pixels and you can make these calculations for your installation.

    Lot of people will go for 20% spare. I typically keep my pixels at 70-80% brightness so that gives more safety margin.

    Sent from my iPhone using Tapatalk
    Dave-1200Px-20KLts

  5. #5
    Join Date
    Dec 2012
    Location
    Hudson MA
    Posts
    3,892
    Post Thanks / Like

    Default Re: Power Supply Equation

    I use 20% and I use 0.06a / pixel


    2019 - Just moved into a new home (yet another change of plans). Will be dim but not dark. Too much to do at the new place to leave time for a show.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  6. #6
    Join Date
    Jan 2016
    Location
    West Bloomfield, MI
    Posts
    660
    Post Thanks / Like

    Default Re: Power Supply Equation

    As a 5 V pixel user with limited power availability, note that with a 350 watt power supply, you can run more than twice as many pixels. Owning an old home with limited outside outlets made this a perfect option for me. My whole show runs from one 20 Amp outlet. 2400 watts available, six 300 watt power supplies running pixels at 50% brightness. Plenty of safety factor even at full brightness.
    Ed
    Happily retired

  7. #7
    Join Date
    Jan 2019
    Location
    Honokaa, HI
    Posts
    14
    Post Thanks / Like

    Default Re: Power Supply Equation

    Aloha,
    Thanks all. I guess I'd seen the equation for fuses when I was researching power injection but didn't really push that knowledge into the next realm.
    Mahalo,
    Sam

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •