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Thread: Pixel power calculator and associated power injection article

  1. #11
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    Default Re: Pixel power calculator and associated power injection article

    One other thing I would like to add (I clicked 'reply' too quickly) is that... I did calculate the equivalent wire gauge for these pixel strings. Again, they are 6" spacing 18 AWG but I understand that the 18 AWG part is a bit notional. I connected six strings of the 6", 50 count pixel strings together and measured the resistance of both the +V and -V wires with my multimeter. I measured 3.2 ohms. Assuming 25 feet per pixel string + another roughly 1 foot for each pixel string for input and output pigtail, that is 156 feet.
    (1000 / 156) x 3.2 ohms = 20.8 ohms. Referencing tables found on the internet, that equates to an effective wire gauge of around 23 AWG. Now, to be fair, if I punch that wire gauge into the RGB Pixel Calculator, the 50% intensity voltage for pixel 50 is showing up correctly as 4.3 V, so maybe that is the answer I was looking for... but the 100% intensity is still not lining up with what I'm measuring.

    Thanks again for reading

  2. #12
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    Default Re: Pixel power calculator and associated power injection article

    Woah man, that is really insane! That kind of a calculator is really great actually, and you know what, I have never seen anything similar to this one! The RGB Pixel Light Power Calculator has to be the best one in this field, that is for sure. I was also looking to start such a project, however I was not sure if it would have any kind of success. Actually, the closest variation of a calculator has to be the one on rocknets.com. They are actually having a hell a lot of great calculators and converters.
    Last edited by Sondiana; 04-18-2021 at 06:27 PM.

  3. #13
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    Default Re: Pixel power calculator and associated power injection article

    Can you provide the link to these?
    Quote Originally Posted by nutz4lights View Post
    I am blaming Bill Porter's awesome YouTube videos for making me question the way I have historically performed some "limit pushing" power injection...

  4. #14
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    Default Re: Pixel power calculator and associated power injection article

    Quote Originally Posted by nutz4lights View Post
    One other thing I would like to add (I clicked 'reply' too quickly) is that... I did calculate the equivalent wire gauge for these pixel strings. Again, they are 6" spacing 18 AWG but I understand that the 18 AWG part is a bit notional. I connected six strings of the 6", 50 count pixel strings together and measured the resistance of both the +V and -V wires with my multimeter. I measured 3.2 ohms. Assuming 25 feet per pixel string + another roughly 1 foot for each pixel string for input and output pigtail, that is 156 feet.
    (1000 / 156) x 3.2 ohms = 20.8 ohms. Referencing tables found on the internet, that equates to an effective wire gauge of around 23 AWG. Now, to be fair, if I punch that wire gauge into the RGB Pixel Calculator, the 50% intensity voltage for pixel 50 is showing up correctly as 4.3 V, so maybe that is the answer I was looking for... but the 100% intensity is still not lining up with what I'm measuring.

    Thanks again for reading
    I agree. I don't get anywhere near the voltage drops he's getting, but then I'm not using the same canned controllers others are, either. I assume people already know not to be hyper-literal about it. I mean, we model the system as an 18AWG wire, and so you solve the problem by connecting the other end of the string to the same power supply with...what...18AWG? If I took it exactly literally, I might think I have to run all my power through 10AWG or something like that. But I know in practice, just follow these principles, and if it works, go have lunch. If it doesn't, play around with the numbers some.

  5. #15
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    Default Re: Pixel power calculator and associated power injection article

    The fact is that many vendors claim 18AWG when in reality you are lucky to get 22AWG (as your calculations have shown). I do power injection all the time. I inject at every 25 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

  6. #16
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    Default Re: Pixel power calculator and associated power injection article

    Quote Originally Posted by ukewarrior View Post
    Can you provide the link to these?
    This is probably the best one.

    https://www.youtube.com/watch?v=eR3QbzjpZy8&t=1416s

  7. #17
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    Default Re: Pixel power calculator and associated power injection article

    Quote Originally Posted by 1pet2_9 View Post
    I agree. I don't get anywhere near the voltage drops he's getting, but then I'm not using the same canned controllers others are, either. I assume people already know not to be hyper-literal about it. I mean, we model the system as an 18AWG wire, and so you solve the problem by connecting the other end of the string to the same power supply with...what...18AWG? If I took it exactly literally, I might think I have to run all my power through 10AWG or something like that. But I know in practice, just follow these principles, and if it works, go have lunch. If it doesn't, play around with the numbers some.
    Glad to hear someone say that they are not getting same numbers... I like the suggestion "if it works, go have lunch" and I have been sort of doing that for the last 7-8 years. However, this oak tree is much different than the way the rest of our props and I really need a better solution. That is what is driving this. I am not interested in changing what we do for the other xx,xxx pixels in the display, just the oak tree, soon to be oak trees when we light up our neighbor's oak as well. I think I am going to move forward with the plan to run single power injection runs with 12 AWG landscape cords that will pop out 18 AWG pigtails to tees every xx feet based on the average branch... I can always have a 5' short cord around if the pop out points don't line up perfectly...

    Thanks for all the replies!

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