Uplights & Backlights

Today’s project is a daunting one. This is the beautiful 1:6 scale desk hand built by Mihail, my carpenter friend in Ukraine. Check out his Furniture for Dolls side gig on Etsy for some amazing craftsmanship. I’m expecting there to be a wealth of 1:1 scale carpentry work there, once Putin is defeated. 🇺🇦

The idea here is to light up a bunch of props sitting atop the desk. So to make room for 12mm diameter LED Pixel Bulbs, I need to drill 1/2” holes in the desktop at strategic places, so as not to obstruct the drawers with the back ends of the bulbs, plus all the wiring.

Why use 12mm bulbs and not 5mm? Well, 12mm is the smallest LED bulb available today that has an IC built in. That chip enables it to be individually addressable as a pixel. The smaller bulbs can only be controlled in groups on a string or in a strip.

In the case of these little phones, the bulbs need to poke through at an angle, and the wires are stiff. So drilling holes through thin plastic, through pot metal, through 1/8” clear acrylic, and through a 3/8” basswood desktop is a rather delicate operation. Especially with dull bits and no drill press. Ace Hardware, by the way, charges way too much for drill bits.

Here’s proof of concept with none of the wires cut, routed and jacked yet. That beer stein only has water in it. The amber hue comes solely from its uplight. The cash register is subtle, but in the dark its translucent features glow nicely. The fake ice under the glass caviar dish is my favorite. The caviar is actually tiny translucent pink glass beads.

I spent the next day cutting and splicing wires using dozens of heat shrink butt splices and three-wire JST connectors, for modularity and to make installation even possible while leaving the drawers functional. No easy trick there, in such tight quarters. There’s got to be an easier way…

The design wound up with six lights up top, and two spares strategically tucked away for possible expansion. Then each of the six large drawers has a bulb mounted into its back panel on 12mm retaining clips, so that I can open the drawers and light up stashes of gold or diamonds or whatever.

So that’s 12-14 bulbs total, consuming 36-42 DMX channels given that each bulb has individually addressable data channels for RGB.

So how does DMX control these LED Pixel Bulbs? Well, to make white light, you send 100% to the red, green and blue channels, using the bulb’s assigned channel range (3 channels per bulb, in sequential RGB order). If you want, say, a shade of yellow, you send equal values to red and green, and set blue to zero.

When a couple more parts arrive today, I’ll daisy chain the desk’s DMX group after the drum kit’s group, which consumes 27-36 channels for nine bulbs and three spares.

So my DMX-512 universe will look like this:

  • Channels 1-35: Chauvet GigBar Move
  • Channels 36-71: Custom nine-piece drum kit
  • Channels 72-113: Custom uplit/backlit desk
  • Channel 114: Chauvet Hurricane haze machine
  • Channels 115-512: Unused for now

Dragonframe, my stop motion animation software, allows you to program DMX lighting sequences that sync with your animation frame-by-frame. So yes, this “power desk” will be pulsing with musical energy, along with my custom drum kit. And that’s the magic — the special effect no one will expect.

And here’s the final product with all the wires routed and jacked. Level of Difficulty compared to other things I’ve done? 7.5

Can’t wait to see it in the next test shot!