2 Pixel Strip Power Amount

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

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donbeu
 
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Joined: Thu Dec 19, 2013 11:55 am

2 Pixel Strip Power Amount

Post by donbeu »

Hey,
I am using two sets of 25 pixels (50 in total) for a project. Both sets of pixels will display the same set of colors, so I do not want to connect them end to end, but instead connect both on different ports in the arduino(so in the arduino I will set one using pins 2 and 3, and another using pins 4 and 5, with the same output conditions). I will be using this for a portable project, so the arduino will be powered through a power supply, and not the computer.

I need to know what to do about powering the pixel strips and the arduino, since I will be using two strips that are not connected end to end.
Do I just power the arduino with the normal 5 V, and the pixels will be fine? Or do I need to power the arduino, and both pixel strips, each with their own power supply of 5 V, or less? Also, for this case, I assume I don't use the dc jack on the arduino, but plug the power wires into the ground and 5 V pins?

Thanks anyone for the help!

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adafruit_support_mike
 
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Joined: Thu Feb 11, 2010 2:51 pm

Re: 2 Pixel Strip Power Amount

Post by adafruit_support_mike »

Each NeoPixel can use up to 60mA, so running a 25 pixel strip flat-out will require 1.25A.

You rarely use that much current though. The human eye responds to light in terms of ratios, not absolute values, so we see "twice as much light" as the same amount of change whether it's a step from 1 photon to 2 (yes, we can see single photons) or 1,000,000 to 2,000,000. A 2:1 change isn't all that noticable though, so you can almost always cut your current consumption 50% without having any major effect on how the LEDs look.

In general, you can drop your actual current consumption to 30% of the max without having to work too hard.

In your case, a 4-AA battery pack should deliver more than enough power to keep everything running (AA batteries can deliver 2A), and we have a whole tutorial on powering LED strips with batteries here: http://learn.adafruit.com/battery-power ... s/overview

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