[Noisebridge-discuss] Massive LED Project at Noisebridge needs your help!

Henner Zeller h.zeller at acm.org
Wed Oct 22 19:14:21 UTC 2014

On 22 October 2014 11:32, Andy Isaacson <adi at hexapodia.org> wrote:
> On Wed, Oct 22, 2014 at 11:04:52AM -0700, James Sundquist wrote:
>> Dana and I have a grand idea for setting up easily programmable LED
>> displays at Noisebridge in a massive matrix. What we need are donations of
>> panels, which will be purchased and shipped by Mitch on his China trip. See
>> our nicely organized wiki page for details, source code, and more info.
>> https://noisebridge.net/wiki/LED
> Awesome idea, awesome project!


(Though I am biased and would suggest to use the RPi version
 it has one realtime challenge right now that I'd like to fix using DMA,
 but it would have the advantage that it would be a thing made by a local
 Noisebridger. The DMA thing is on my list as soon as the access control
is finished)

> A few suggestions, note that this is totally not backseat driving and
> y'all should totally do the thing whatever way works for you. :)
> 1. Consider getting WS2812 pixels rather than cheaper knockoffs, and
> driving them with Fadecandy http://www.adafruit.com/products/1689 rather
> than other solutions.  Fadecandy has truly incredibly beautiful
> dithering, giving much much nicer subtle color gradients compared to
> straight PWM systems.  Micah (aka @scanlime, creator of Fadecandy) has a
> really nice installation of Fadecandy open to the public sidewalk at 80
> Turk St in the Tenderloin, and if you check it out at evening and then
> walk over to Yerba Buena Gardens and check out their currently installed
> non-Fadecandy LED art you can really tell the difference.

The WS2812 are way more expensive per pixel than the $20 32x32 RGB matrices

> However I see you're aiming at doing video, which I don't know if that
> is very well supported with fadecandy; would require additional
> research.

There is also PixelPusher.

> 2. Don't use an ATX power supply, get an appropriate 5V power supply
> that's properly sized for the application.  It'll be cheaper, overall,
> and easier, and save power.

+1. The Panels use a _lot_ of current. A 32x32 panel needs 3.4A tops, and there
are already  40A+ 5V power supplies readily made for these kind of
things (on ebay
in the $20-30 range). ATX power supplies typically only have 20-25A on
the 5V rail, and
useless 12V and -12V rails.

> 3. the LED wall panels are somewhat expensive per pixel, last I looked.
> It can be cheaper to get the flex-pcb strips and mount them to panels
> yourself, then mount diffuser panels appropriately.

Not sure about that.


> -andy
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