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

[Dan Cote]

I have a few pixelpusher installations out, and some open software that can
drive any pixel tech. You wanna locate your pixels close to the power
supply or else you end up with ridiculous thick wire gauges. Don't use atx
power supplies.

Diffusion is key. If you don't diffuse, the light is coming from points.
They hurt to look at. With diffusion, the light is spread out and better
looking.

Here is a low res (40*12) video wall with wax on acrylic that we made with
36mm pixels. They are 12v, and you can use server power bricks (12v only)
to run them. It was around $500 for the pixels. They use 2801 chips.

https://www.youtube.com/watch?v=a0-NG26shxg
https://www.youtube.com/watch?v=GTs0EQAq1_c

http://www.alibaba.com/product-detail/36mm-2801-led-pixel-wall-light_664267133.html

On Wed, Oct 22, 2014 at 12:14 PM, Henner Zeller <h.zeller at acm.org> wrote:

> 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!
>
> +1.
>
> (Though I am biased and would suggest to use the RPi version
>    https://github.com/hzeller/rpi-rgb-led-matrix
>  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.
>
> -h
>
> >
> > -andy
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