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How to power my LED Strips? Answered

Q: How can/should I power my LEDs?

Info: I am using 3m of adafruits 144 LED strips and 4m of the 60 LED strips.

144 LEDs             https://www.adafruit.com/products/1507
60  LEDs             https://www.adafruit.com/products/1138
My Power Supply http://www.newegg.com/Product/Product.aspx?Item=N82E16817151110
Micro Controller   http://www.newegg.com/Product/Product.aspx?Item=286-0002-00003

I would love if I could somehow use my computers power supply to help power these lights, however I doubt this is possible with the amount of wattage/amps these guys will pull since I am using so much. So should I pick up a dedicated power supply? If so from where?

Whats the best way to do this as well?



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Jack A Lopez
Jack A Lopez

7 years ago

You read the manual, right?



Well, I didn't read it either, not in its entirety, because I just learned about these neopixel(r) thingies just now, but I think the relevant technical details are as follows:

Each neopixel(r) has four pins: +5V, ground=0V, data_in, and data_out.

As far as power is concerned, all your neopixel modules, are wired in parallel, so the combined current draw from all of them is just the algebraic sum over all the individual currents drawn by each module.

The maximum current draw of a single neopixel is 60 mA, and corresponds to all three channels, {R,G,B} at full current, which corresponds to blinding bright white.

So the maximum possible current draw for a set of N neopixels, is N multiplied by 60 mA. E.g. if you had N=100 of them, then the maximum current draw, corresponding to all 100 turned on bright white, would be 100*60 mA

= 6000 mA = 6 A. Since everything is drawing from the same 5 volt bus, this is a power draw of 5V*6A = 30 W.

Anyway, that's how the power calculations work out, for calculating the maxium power draw.

By the way: (3*144+4*60)×0.060 A = 40.32 A

In terms of power that's 5V*40.32 A = 201.6 W, which seems to me like a sick amount of power.

If you think the assumptions for maximum power draw are unrealistic, because you are certain there will be no circumstance in which all of your pixels are driven bright white at the same time, well then maybe you need a different estimate for the sort of "average" current draw seen by your pixels. There was some discussion of this on page 21, of that uberguide pdf I linked to above. I think the author of that was saying an estimate of 20 mA per neopixel module was more realistic for a typical multicolored sequence. That's 13.44 A in the case of 672 pixels all with an instantaneous average current of 20 mA.

And that might be a good assumption, as long as you're confident that your code is not going to screw up and turn all the pixels bright white for some reason.

Regarding the data pins. I think these are chained from one neopixel
module to the next. That is: your microprocessor drives data_in, on
module 1.

Then module 1's data_out drives module 2's data_in.

Then module 2's data_out drives module 3's data_in.

... and so on and so forth, until module (N-1)'s data_out drives module N's data_in.

So the (i+1)th module sort of "inherits" its color from the ith module that is upstream from it. So the color on each pixel changes every, period, however much time it takes to clock 24 bits down a serial line, or however they're doing it.

I am guessing that's how these things do their thing.


7 years ago

Adafruit sell suitable power supplies for Neopixel strips. Though with that many you might need a bigger one.