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Thread: Basic questions about my setup

  1. #1
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    Default Basic questions about my setup

    I am setting up my first mega tree this year. It is a 16x50 setup. I am just using 8 channels with 100(12v) pixels each. I have attached a picture of the setup below.

    First question, am I correct in figuring that for 800 pixels, I will need 48Amps so 2 power supplies?

    Second question, do I need a jumper between the GND and V- on my power supply?

    Third question, what is the proper fuse to use between my power supply and controller?

    Last question, if I end up needing to power inject do I just need run one pigtail off of the power supply(with only V+ and V-) and then use one Tee to go to the end of each strand? I found a bunch of documentation on why you need Tees but not how to physically connect them. See the (terrible)drawing below for what I am thinking.

    Controller setup


    Power injection setup?


    Thank you!

  2. #2
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    Default Re: Basic questions about my setup

    Quote Originally Posted by pmkoch View Post
    First question, am I correct in figuring that for 800 pixels, I will need 48 Amps so 2 power supplies?
    At 12v an unregulated pixel uses 0.72w. Each string of 50 will use 0.72w * 50 = 36w A 12v 360W supply can drive 8 legs: 8*36w = 288w The rest (20%) is reserved for overhead. You should be able to make this work with two supplies

    Quote Originally Posted by pmkoch View Post
    Second question, do I need a jumper between the GND and V- on my power supply?
    NO. THE GND is Chassis ground and has nothing to do with Signal ground aka V-. The Line/Neutral/GND connections should be coming from your mains supply.

    Quote Originally Posted by pmkoch View Post
    Third question, what is the proper fuse to use between my power supply and controller?
    I would use a fuse per leg. Each pixel draws 0.06a * 50 = 3a. I would use a 5a fuse. HOWEVER, this is the wrong way to perform this calculation. The fuse is there to protect the wire. You need to determine the max current the wire in a leg can handle and pick a fuse that protects the wire.

    Quote Originally Posted by pmkoch View Post
    Last question, if I end up needing to power inject do I just need run one pigtail off of the power supply(with only V+ and V-) and then use one Tee to go to the end of each strand? I found a bunch of documentation on why you need Tees but not how to physically connect them. See the (terrible)drawing below for what I am thinking.
    For 12v pixels in a 50 pixel string you would only need to power inject at one end (start/end is your choice). If you provide power from the controller then you need to keep the distance from controller to first pixel pretty short (how short depends on the wire you are using). I rarely ever provide power from my controller and prefer to use 16AWG wire from the PSU to each leg. One wire for each leg (the legs on my tree are 100 pixels).


    2020 Full sized show reworked for the new location. Only adding (famous last words) 13 RBLs that I finally got converted to using pixels
    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. Dim show (3000 pixels) had regular visits most nights.
    https://www.youtube.com/channel/UCyX...ttrsZNARkUce0Q

  3. #3
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    Default Re: Basic questions about my setup

    Quote Originally Posted by MartinMueller2003 View Post
    NO. THE GND is Chassis ground and has nothing to do with Signal ground aka V-. The Line/Neutral/GND connections should be coming from your mains supply.
    Okay, I read it in the wiki and this was the discussion that mentioned it so that is why I asked: http://doityourselfchristmas.com/for...715#post282715

    Quote Originally Posted by MartinMueller2003 View Post
    I would use a fuse per leg. Each pixel draws 0.06a * 50 = 3a. I would use a 5a fuse. HOWEVER, this is the wrong way to perform this calculation. The fuse is there to protect the wire. You need to determine the max current the wire in a leg can handle and pick a fuse that protects the wire.
    Each leg is 100 pixels so wouldn’t I need a 6+ Amp fuse?

    Quote Originally Posted by MartinMueller2003 View Post
    For 12v pixels in a 50 pixel string you would only need to power inject at one end (start/end is your choice). If you provide power from the controller then you need to keep the distance from controller to first pixel pretty short (how short depends on the wire you are using). I rarely ever provide power from my controller and prefer to use 16AWG wire from the PSU to each leg. One wire for each leg (the legs on my tree are 100 pixels).
    Each leg is actually 100 pixels(50 up and 50 down) so that is why I asked about power injecting on the end of each strand. I have read quite a few people having success powering 100 pixel strands with no power injection but does that count for strands that are getting power from the controller?

  4. #4
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    Default Re: Basic questions about my setup

    i have been using 128 pixel 12 volt 18 gauge wire with a 7 foot lead from the controler (falconv3) for over 6 year and i did used injection at the end but i am running 100 % power ,,,and when i disconnect the injection i can see a little of pinkins (on full white ) at the end of the 128 pixel .... then i test 200 pixel at 40 % and barely see pinking so i am sure if you are using 100 pixel (instead of 128 ) you wont see no need of injection ..just try it and you will be amaze ,, as for fuse ..i also never used them but my show is outside under below freezing point ... this year i will try to used them as i am going bigger lol
    also looking at your picture if you are not using any of the other pixel bank i would separated then... 4 on each side that way the board does not work as hard (power) so 1.2.3.4 then /// 9..10 ..11..12
    Last edited by barbotte; 06-24-2020 at 11:02 PM.

  5. #5
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    Default Re: Basic questions about my setup

    Quote Originally Posted by pmkoch View Post
    Each leg is actually 100 pixels(50 up and 50 down) so that is why I asked about power injecting on the end of each strand. I have read quite a few people having success powering 100 pixel strands with no power injection but does that count for strands that are getting power from the controller?
    Running 100 pixels per leg/string on 1 output from the controller at 12V DC should not require power injection on both ends, just the end that is physically connected to the controller. I run 18ga wire from my E682 to each of my 12 legs/strings with a connector wire that is about 5` long, and run all 1200 pixels on my mega tree with just 2 12V PSUs. Now, before you gasp and tell me it's all wrong, I only run my mega tree at 50% power (that is set on the E682 for each output), and later in the season this last year, when I was trying to capture video of my display I cut that output down to 25% because I was getting too much saturation in my video. I also found that doing so didn't alter the display all that much and left it there for the remainder of the season. If you *are* planning on running your tree at full 100% power, the advice Martin gave you above should be followed.

  6. #6
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    Default Re: Basic questions about my setup

    Those are my thoughts too. I run mostly led traditional christmas lights so last year I think I had my pixels at like 30% for them to blend in. I obviously want the tree to stand out a bit but I don't see me pushing over like 60% brightness on it.

    I hooked everything up last night and ran some test cycles and everything was looking good so I am just going to try without power injection first but I have the cables/tees just incase I need to.

    I ended up running the 5A fuses on the legs between the PSU and controller and haven't blown them yet.

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