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Thread: String length, amps and power injection

  1. #31
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    Default Re: String length, amps and power injection

    Thanks! A scope I do not have nor know how to use... But good to know that if I am happy w/ the 70% brightness level, then I should be able to plan power according to the amperage measured.

    I should also mention that I don't know if there is a standard way to set brightness percentage, or if it is device specific. I say this because I've seen indication from posts on this forum that it is common set brightness to maybe 50% on a roofline, or 30% on a megatree or other dense props. At 50', I think my roofline would be better served at 70-80%, and I'd find it hard to imagine the 30% level of light that I saw being sufficient for a megatree (but I'll know for sure next year when I build one . Mentioning this b/c I'm not sure how much my brightness percentages should be taken with.

    Regards,
    - pc

  2. #32
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    Default Re: String length, amps and power injection

    Quote Originally Posted by puppycrack View Post
    Thanks! A scope I do not have nor know how to use... But good to know that if I am happy w/ the 70% brightness level, then I should be able to plan power according to the amperage measured.

    I should also mention that I don't know if there is a standard way to set brightness percentage, or if it is device specific. I say this because I've seen indication from posts on this forum that it is common set brightness to maybe 50% on a roofline, or 30% on a megatree or other dense props. At 50', I think my roofline would be better served at 70-80%, and I'd find it hard to imagine the 30% level of light that I saw being sufficient for a megatree (but I'll know for sure next year when I build one . Mentioning this b/c I'm not sure how much my brightness percentages should be taken with.

    Regards,
    - pc
    This video is from. The road at 40', both the matrix and tree are at 35%, the mini trees are at 40% as well as the windows and props on the wall.
    https://fb.watch/30RL1qKh8T/

  3. #33
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    Default Re: String length, amps and power injection

    FYI: post #29 was just edited. Not sure why, but additional testing cast suspicion on my original amperage numbers. Subsequent testing (ran twice this time, each on a freshly booted ESPixelStick) showed different results. The data has been updated.

    Regards,
    - pc

  4. #34
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    Default Re: String length, amps and power injection

    You are showing a linear relationship between brightness setting and power usage which is not what my usage of PWM driven LEDs has shown (OK I did my tests 20 years ago so...).


    2021 New Tune-to sign. New 40x27 matrix at the house. Retiring the Strip based matrix. Updating some of the old window frames to the new house. Adding two new songs.
    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/user/MartinMueller2003

  5. #35
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    Default Re: String length, amps and power injection

    Quote Originally Posted by dim bulb View Post
    This video is from. The road at 40', both the matrix and tree are at 35%, the mini trees are at 40% as well as the windows and props on the wall.
    https://fb.watch/30RL1qKh8T/
    Thanks for the link, but I don't have FB.

    As I've now come to realize, not all pixels are created equal (or even close). After testing some other pixels I got from Amazon, I see that the amperage / pixel, and therefore brightness, can vary by quite a lot. So my 30% may not be the same as your 30%, depending on where the LEDs came from.

    I'm also seeing what looks like some different efficiencies between different pixels. The square node from diyledexpress seem to be emitting ~10% more light per amp compared to the bullet nodes from Nova Bright. Not sure if this is due to better LEDs, or the form factor at this point though.

    Regards,
    - pc

  6. #36
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    Default Re: String length, amps and power injection

    Quote Originally Posted by MartinMueller2003 View Post
    You are showing a linear relationship between brightness setting and power usage which is not what my usage of PWM driven LEDs has shown (OK I did my tests 20 years ago so...).
    I'll admit I was quite surprised as to the results based on what I've been reading on this forum. But I did the test 2x, each on a freshly booted ESPixelStick. Perhaps my testing is flawed by using a simple Innova 3220 Multimeter for measurements as opposed to a scope?

    I also tested the 12v 50-node bullet pixels from Nova Bright (Amazon), and had slightly different findings (again, tested 2x):

    Code:
    % white	amps	amps %’age of 100 brightness	amps/pixel
    100     1.8                                     0.036
    90      1.68    93.33%                          0.034
    80      1.54    85.56%                          0.031
    70      1.38    76.67%                          0.028
    60      1.23    68.33%                          0.025
    50      1.06    58.89%                          0.021
    40      0.9     50.00%                          0.018
    30      0.73    40.56%                          0.015
    Regards,
    - pc

  7. #37
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    Default Re: String length, amps and power injection

    You need to add another control to your testing. That is, light intensity. Different pixels may have different LED's and different current. So, light intensity will be different and this should be measured. Then, you will need to normalize results by light intensity.

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