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Specifics of powering long neopixel strips
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Specifics of powering long neopixel strips

by dgnuff on Sun Jun 13, 2021 4:12 am

I'm starting to work on a Christmas tree light setup using a Pi Zero W and three strands of these babies: https://www.adafruit.com/product/3631 plus two of these little gems: https://www.open-electronics.org/a-chri ... ixel-leds/ for a grand total of 172 neopixels. With some of the display patterns I have in mind, I can see the whole lot being on with each individual neopixel drawing maybe 30 Ma. That's pushing five amps all together. Can I send that much current through the entire lot, or should I have a second feed point part way up?

If I do run a second power feed, obviously I don't need to connect the two +5 wires together at the break just below the second feed, but do I run the ground the whole way along the strip or break it as well?. In audio design, you'd never run it the whole way. because that would introduce a ground loop which can cause an awful hum. However digital is a very different animal, and I'm concerned about passing data between two neopixels with grounds that are connected to each other, but by a very circuitous path.

Yes, I did read the sticky at the top of the forum, all it had to say was:

> 1. Make sure you have adequate power. Longer strips may require power fed to multiple positions on the strip.

with no details on how long is a "Longer" strip, and how exactly to handle the ground wire.

dgnuff
 
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Re: Specifics of powering long neopixel strips

by adafruit_support_bill on Sun Jun 13, 2021 6:16 am

Can I send that much current through the entire lot, or should I have a second feed point part way up?

The wires in those 'dot' strands are rather thin. I'd go with multiple feed points.

If I do run a second power feed, obviously I don't need to connect the two +5 wires together at the break just below the second feed,

If you are using a single supply with multiple feed wires, then it is best to keep both 5v and ground wires contiguous through the strand.

If you are feeding from two separate supplies, you would want to keep the 5v power sections separate, but still keep the ground contiguous.

adafruit_support_bill
 
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Re: Specifics of powering long neopixel strips

by dgnuff on Sun Jun 13, 2021 9:08 pm

Thank you for the reply.

I should have stated that I will be running everything from a common 5v power supply: https://www.adafruit.com/product/658 . So your information that I should have both +5 and Gnd contiguous up the entire strip is exactly what I need to know.

dgnuff
 
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Joined: Wed Dec 30, 2015 6:16 pm

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