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I am interested in creating a string of ~80 RGB LEDs run on an Arduino Uno. Each LED is to have its own on/off timing and color and the distance from one LED to the next about 4-5 feet.

Since I want to program each LED separately can I do that with strings like the Adafruit Pixels (https://www.adafruit.com/product/322) or do I have to set it up with separate RGB LEDs and daisy chain them?

Thanks for your help with this.

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  • Because of the distances, I'm tempted to suggest going with DotsStars instead of NeoPixels. Those have a separate clock line, so you could run them slower, if there's too much interference.
    – Gerben
    Commented Feb 17, 2020 at 16:33
  • Since you'd have to change the wires anyway, adafruit.com/product/4356 might be better than the ones you linked.
    – Gerben
    Commented Feb 17, 2020 at 16:34
  • Good recommendation Gerben. I will definitely consider that and would probably be cheaper then the ones I was looking at given the fact that I need 80 ish.
    – China Blue
    Commented Feb 17, 2020 at 23:34

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do I have to set it up with separate RGB LEDs and daisy chain them?

That's exactly, what the string of Neopixels, that you linked, is: Separate WS2801 RGB LED chips, which are daisy chained together. Since the distance of the LEDs on the string is not 4-5 feet, you cannot use the string directly.

You can either cut the string and extent the cables, as you need to. Or you can buy single LEDs and use completely your own cables. That's up to you; technically it is completely the same.

But since 80 LEDs, each 4 feet apart, will give you about 100m/330feet, you get a problem with the resistance of the wire. First about power supply:

You whole strip would need up to 4.8A of power, with every pixel at full white. You need to transport that current from your source, down to the very last LED. Make sure, that the used wire has very low resistance and is rated for such a current. If the resistance is to high, you will loose voltage over every meter of the cable and the last LEDs might be off color or not working.

I think the signal lines will be fine despite the distance, since every LED outputs them again to the next LED, so the signal should be kind of refined on every LED (though I don't know, how the WS2801 chips work internally).

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    Re “I think [...] the signal should be kind of refined on every LED”: this has indeed been observed.
    – Edgar Bonet
    Commented Feb 17, 2020 at 8:41
  • It wasn't clear to me that that is what the neopixels do. That is super! Can you point me to code that illustrates how to manage each pixel separately? The only examples I have seen create overall patterns. I want one pattern that loops per pixel and separate from the group. Thanks also for the power and signal comments they are good to bear in mind.
    – China Blue
    Commented Feb 17, 2020 at 23:23
  • @ChinaBlue The code for iterating over each pixel depends on the library used. I've had success using FastLED with a Neopixel WS2811. Here's a code example setting each LED in a loop.
    – sfmiller940
    Commented Feb 19, 2020 at 23:24

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