Fa-la-la display

I thought it would be fun to animate the refrain from "Deck the Halls" and my vision was something like this where each syllable stood on its own so it could be placed anywhere in the yard, could be any color and yet would not require a lot of wiring or require a million channels to control.

As each sign would have RGB capability, I decided it would be efficient to use "dumb RGB bullet" light strings instead of smart pixels (externally they appear to be very similar in shape and size) yet "dumb" RGB strings need only 3 control channels for the entire string whereas smart pixels require 3 channels for each light in the string. "Dumb" bullet lights can easily be mistaken for the "smart" WS2811 pixels, but generally speaking, you'll find that the "smart" pixel has a longer body and may have only 3 wires while the "dumb" style always has 4-wires. (Note that "smart" pixels sometimes also use a 4-wire mechanism, so exercise caution when working with bullet-style lights, pixels or dumb RGB...)

I decided that it would be efficient to use pixel technology because of the convenience of the wiring and structure of the WS2811 auto-addressing mechanism built into "smart" pixels. However, the WS2811 chip can't accommodate the larger current requirements of multiple RGB LEDs connected together such as the dumb RGB bullets, so I devised a "Pixel-SSR" which used a single WS2811 chip that controlled a three-channel DC SSR because there would be many more LEDs to control than just a single RGB LED, which is what the WS2811 chip is designed to do. So the DIGWDF Pixel-SSR was born and a set of 9 assembled, one for each of the nine syllables:

18 pieces of coroplast measuring 16" x 16" were cut from a single 8'x 4' coroplast sheet and 7/32" holes drilled through nine of them to hold the dumb RGB bullets snugly. A master template (drawn freehand) was made so as to position the holes in consistent locations for each of the "la" syllables. The undrilled pieces would form the back sides of each element.

To minimize the wiring, each Pixel-SSR was fitted with a short female input connector and a 6' long wire with a male connector (output) soldered onto the end. The long wire afforded an easy way to space the syllables apart a distance, making each element self-contained and ready to connect to the next one without additional extension cables.

Nine frames were constructed using inexpensive framing-grade 1x3 pine. To form the frames, thirty-six 15-1/2" lengths were cut and assembled using wood glue and sheetrock screws. The finished frames were 16-1/4" square, slightly larger than the coroplast panels, allowing for construction anomalies... (We weren't building furniture and there was no need for all measurements to create a perfectly square frame. We deemed "close" as good enough for our needs...)

Following the setting of the wood glue, 1/4-20 6" bolts were installed in what would be the "bottom" of the each frame -- these would become the built-in stakes that would serve to hold each frame vertical. The frames were also painted white to match the coroplast material. Following that, the coro panels were glued/sealed to the frames on one side using clear silicone glue.

The dumb RGB bullets were inserted into each frame/box and electronics were installed using super-sticky foam tape. Being the first syllable of the refrain, the "fa" box received the DIGWDF MiWiFi controller with ESP module and Pixel-SSR (left photo) while the "la" boxes were fitted with only a Pixel-SSR (right photo).

Prior to gluing/sealing the back sides with another piece of 16"x 16" coro, a running test was made. A single 14A 5vdc power supply, mounted in the 5th box, powers the entire display. The 5th box was preferred as the power distribution would be more even across all 9 boxes if powered from the center. Video test: https://vimeo.com/312800951 The back side of each box has a small access flap cut for accessing the wiring or, in this example, the ESP module in the "fa" box. Other than these small access flaps, the silicone glue completely seals the boxes from any water leaks, and unless we have a flood, it's quite doubtful any water will get in through the access flaps themselves. And even if it did, there are no electronics mounted near the bottoms of the boxes. Interior condensation is a possibility, and after a year of use, we'll see if one or more drain holes drilled along the bottoms are necessary.

To finish the project, short sections of common wooden dowel material were cut and glued at the corners of the backs of each box. These serve as stand-offs so that the boxes can be stacked on top of one another without pressing on the RGB bullets. Total cost of this display piece including all electronics and RGB bullets was <$150. This entire display uses only 27 channels of control -- essentially a "string of 9 pixels" for configuration reasons. Had I actually used "smart pixels" instead of the dumb RGB bullets, the same display would have required 576 channels -- two universes. As it is, this will be much easier to sequence.

-Dirknerkle