powering neopixel strip (& feather) from USB brick

EL Wire/Tape/Panels, LEDs, pixels and strips, LCDs and TFTs, etc products from Adafruit

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aaronaverill
 
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powering neopixel strip (& feather) from USB brick

Post by aaronaverill »

I'm looking to build an outdoor interactive art sculpture from NeoPixels driven by a Feather M0 that stays lit up all night long (dusk to dawn) and doesn't have access to 120V power. I'm able to change batteries during the day, then fire it up again at dusk, and will also be able to recharge batteries from a generator away from the art.

So I'm looking at my 12000 mAh USB brick, which has 5V 2.1 amp output. Assuming I stay under 2 amps for the pixels (about 35 full brightness, 70 half brightness) is there any reason I can't use that to power the Feather + NeoPixels straight off the USB pin on the board. I mean, it's a super simple solution, the USB bricks are a dime a dozen, and if I need more run time I can get a bigger one, and I can just plug the brick into the generator to charge it during the day (or have a few spares, at < $15 a piece)

Am I under thinking this or is it that simple for any project under 2 amps that needs to run less than 10 hours and doesn't have a weight constraint.

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Franklin97355
 
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Re: powering neopixel strip (& feather) from USB brick

Post by Franklin97355 »

Neopixels like to have the data pin voltage near the power voltage but will sometimes run with 5-volt power and 3.3-volt data. Otherwise, l see no reason this should not work.

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happyinmotion
 
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Re: powering neopixel strip (& feather) from USB brick

Post by happyinmotion »

No reason at all - I've done this for several projects. It's a cheap and easy way to get a solid 10 Watts all night.

I did discover one fishhook to watch out for. All the USB batteries will power down after thirty seconds or so of low power use. Then they won't turn back on unless the connected load draws substantial power.

One of my projects was a box with a Feather and internal lighting that only lit when the box was opened. The Feather alone didn't draw enough power to keep the USB battery awake, so the battery would power down, the Feather would stop running, and it wouldn't turn on when the box was opened.

If your LED project is glowing most of the time, then you're fine.

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aaronaverill
 
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Re: powering neopixel strip (& feather) from USB brick

Post by aaronaverill »

oohh.. interesting, and that makes a lot of sense. could that be fixed by also plugging in a lipoly to keep the feather running?

also I found a hack to pulse the battery to fake it into staying away. lol. clever.

https://www.dorkbotpdx.org/blog/paul/battery_pack_load

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happyinmotion
 
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Re: powering neopixel strip (& feather) from USB brick

Post by happyinmotion »

Ah yeah, I remember reading that article when trying to debug my art project.

I also just pulsed the power on for a bit. I could flick the LEDs on, coz they were hidden inside the box. I seem to remember it was one LED for 10 ms every 20 seconds, or thereabouts. That was sufficient to keep the battery awake.

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