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Thread: 3400+ LED display - Wiring question..

  1. #1
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    3400+ LED display - Wiring question..

    Hello

    I'm building a custom video display using a Teensy 3.1 + OctoWS2811 adapter to control 24 strips of 145 WS2812B LEDs,

    Total LEDs - 3480

    Each 3 strips are daisy-chained together to form one group, and each group is connected to one of the eight LED outputs on the Octo adapter.

    On my first attempt, the first strip of each output worked OK but the second and third strips go haywire and blink uncontrollably.
    I posted a diagram of the wiring i'm using, I have a feeling this has something to do with the ground wires somewhere..

    As shown in my wiring diagram, i didn't chain the grounds at the end of each strip to the next (like i did with the data cables), each strip gets a ground at the beginning only.
    I also didn't connect a ground or +5V power directly to the Octo, it's powered and controlled using the USB jack and it's connected to the LEDs using the two CAT 6 jacks.


    Anyways, what should i change / do ? What are the 'rules' for wiring ground wires with addressable LEDs?
    Thanks!
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  2. #2
    Senior Member PaulStoffregen's Avatar
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    You probably need to feed power to both sides of each LED strip.

    Of course, try with just one group of 3 strips first, to see if it makes a big difference.

  3. #3
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    Thanks!
    What about the grounds? I didn't chain the grounds at the end of each strip to the next (like i did with the data cables), Should I?
    What about adding a +5V and ground directly to the Octo?

  4. #4
    The system works !
    https://www.youtube.com/watch?v=G5PR7MRMI7M

    short story:
    Use wide wires to avoid voltage drop across them. Follow AWG standard.
    The LEDs did not receive enough Volts when the animation is bright. Reducing video brightness stabled the system.

    long story:
    We measured the voltage across the wires (which should have been wider based on AWG calculations) and ran few tests programs (Black, Red, Green, Blue and White).
    The system wires took some of the voltage and apparently much more than it should.
    When running 1200 leds in bright colors the leds started to go crazy and blink randomly.
    When running 1200 leds in a less bright colors the leds were stable and the animation was smooth.
    solution:
    1. Replace some of the wiring to wider cables.
    2. Increased the PSU output voltage from 5 to its maximum which was 5.4 (using its internal Adjust screw button).
    3. Reduce the brightness of the video output. Above certain brightness, the system becomes unstable and leds blinks randomly.

  5. #5
    Senior Member PaulStoffregen's Avatar
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    Yup, delivering so much power to so many LEDs is tough. Glad you got it working.

    It's always awesome seeing thousands of LEDs!
    Last edited by PaulStoffregen; 04-07-2015 at 10:39 PM.

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