Christmas 2012

Cinderella’s Castle

In the fall of 2011, we were lucky enough to visit Walt Disney World in Orlando.  We spent the day and evening there, and were gathered around Cinderella’s castle for the evening lighting ceremony.  It was a magical moment, and the shaky cell phone photo taken above became the inspiration for our decorations this year.

(All photos in this post may be enlarged with a single click.)

Cool Lights w/ Green.
2012 House + Lights. 
Green + Warm Walls


Our goal this time was to create something beautiful, classy and memorable.  We wanted still images which could stand on their own, plus  sequences which could gracefully flow and be complemented by music.

I think we succeeded in grand style.

A couple of still photos are included above, and the boring technical details below.  I’ll post some video and more stills in a week or two.


  • The stone face of the house is covered with warm and cool white LED panels.  We lost track of the exact number installed.  The CAD guy in our builder’s office claims that there’s about 944 square feet of stone which need to be covered.  Each panel of lights measures 2 meters x 1 meter.  Total LED count here is somewhere in the 22,000 – 24,000 range.
  • 240 watts of LED floodlight.
  • ~4,100 discretely controlled RGB bulbs on the 25′ tree.
  • ~150 ‘sparkle’ lights (higher power, 3 x RGB emitters in a single package), also on the façade.
  • More RGB bulbs on the rooflines.  Maybe 250 – 300?
  • 28 (?) universes of DMX over ethernet, totaling ~ 5 megabits per second of data throughput.
  • Custom designed DC dimmers and Art-Net–> DMX bridge interfaces.
  • Lighting computer jam syncs to time code generated by audio computer, which keeps things nicely locked together.
  • Small radio transmitter broadcasting in stereo on 87.7 MHz.


A huge challenge was figuring out how to attach the lights to the house’s stone walls.  It’s done in ‘dry stack’ style, which means that most of the stone sections stick out 1/2″ to 3/4″  in front of the mortar.  So there’s lots of area to grab on to, but the shapes are very irregular, with often non-parallel sides.

I considered C clamps (too much money, didn’t want scratched rock) and plastic alligator work clamps (didn’t open wide enough, except for the super expensive ones).  At 200-300 pieces required, cost starts to increase in a hurry.

Plastic Conduit – 2.5″ and 3″ sections

While trolling through Lowes I found a perfect solution.  Plastic gray PVC electrical conduit is available in many diameters.  I bought 10′ sections of 3″ and 2.5″ pipe to test.  Using a chop saw, I cut a section of pipe in narrow bracelet-sized pieces, with widths varying between 3/16″ and 1/4″.  Then, I used the same saw, I cut about 50 degrees out from each circle, leaving me with a section of plastic which looked a bit like PacMan.

These sections were both very flexible and very strong.  They easily stretch to the width of a stone section, but also grab tightly when released.

Pipe Clamp Grabbing the Rock

For $40 in pipe (and a lot of annoying plastic powder kerf), I’m absolutely thrilled with the results.


I designed a daughtercard which, through a short section of ribbon cable, mates with Parallax’s Spinneret ethernet module.  And thus, a two universe Art-Net to DMX bridge was born.  Parts cost for the daughtercard was just a few dollars.  It works beautifully, running at an easy 44 frames per second on both outputs.  If I get some time in January, and if there’s any interest, I’ll release the .spin code I used..  Size of the card is only about 1″ x 3″, which is nice and compact.

In this case, the panel lights use one universe and the floodlights are on the other.

Art-Net Bridge Card for Parallax Ethernet Module
Art-Net bridge module, mates with Parallax’s ethernet / Propeller development board, the Spinneret. Includes 2 x XLR5 output jacks and proper RS485 drive stages.

2 universe Art-Net bridge. Not shown is the ribbon cable which connects the two.

The house face lights use 120 channels of  one universe and the flood lights 12 of another.  Crazy that it’s easier – at least in this case – to add a universe than to run more cable between here and there.

The stone face lights are controlled by five DC DMX dimmers I designed.  Each drives 24 discrete outputs or 12 warm/cool pairs.  Everything except the 24v/2.5A power supply fits on a 3″ x 5″ PCB card, which is nice and compact.  The drive stages are rated at 2A each, but the panels only draw about 80 mA each.  That leaves plenty of headroom, and no noticeable heat is generated anywhere on the card.  Connectors on the left are for Neutrik’s Ethercon series.

Earlier this summer I previewed some different styles of net light.  I was concerned because all of the AC-driven ones flickered annoyingly when I glanced my eyes back and forth across them.  The flicker was at either 60 or 120 Hz, and it bothered me.  It’d be easier, I reasoned, to go with custom panels which could be directly DC powered.

So I asked the factory to modify an existing design for +24v DC operation, which they did nicely.  The dimming engine runs at a 5 KHz refresh cycle, which means the light output is both camera- and eyeball friendly.

Power Draw: 4 LED wash lights + 24 channels of house panel light.

Power Draw – 4,080 RGB nodes on tree

Total data rate is ~ 5 megabits per second sustained.

Questions?  Comments?  It’s truly beautiful to see at night.




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