LED-based Nixie tube-esque displays at ESC Minneapolis 2017

August 26, 2017

Max The Magnificent-August 26, 2017

While I certainly appreciate the advantages of the wide range of modern display technologies we can deploy in today's electronic systems -- like liquid crystal displays (LCDs), for example -- I still have a soft spot for many of their predecessors from yesteryear.

Take Nixie tubes for example. These add a certain je ne sais pas to any system. In addition to requiring ~170V to light them up, however, their big downfall is that the larger ones can be really hard to find and -- when you do find them -- their price-tag tends to make your eyes water.

Generally speaking, you have to either salvage your Nixie tubes from old equipment or purchase "New Old Stock" from around the Internet. I know of only one guy -- Dalibor Farny -- who makes fantastic tubes from the ground up (see The Art of Hand-Crafting Nixie Tubes). In fact, I'm using a special custom-built set of Dalibor's Steampunk tubes (bronze bases, copper anodes) in one of my own projects, but that's a story for another day.


(Source: Dalibor Farny)

Recently, I took delivery of something called a Lixie. Created by Connor Nishijima, this is a LED-based interpretation of a Nixie tube. Take a peek at this video, which shows my first experiment with my little Lixie.

I'm afraid my amateur video doesn’t do the Lixie justice; this really is an awesome-looking display. It's formed from 10 thin slices of acrylic, each 2.5" wide and 3.75" tall. Each slice is laser-etched with its own digit from 0 through 9. Initially, Connor used only a single line to represent his digits, but he subsequently opted for a dual-line format as illustrated below.


(Source: Connor Nishijima)

I really like the font used in these displays. It reminds me of my Nixie tubes. It turns out that this isn’t too surprising. When I asked Connor how he came up with this font, he told me that he dismantled a failed Nixie tube, placed its digits on a scanner, scanned them into his computer, scaled them up, and progressed from there.

In order to light his Lixies, Connor employs two WS2812 tri-color LEDs per digit (see Using WS2812-based NeoPixels in embedded systems). Even though these come in teeny-tiny 5mm x 5mm packages, it's still a tight squeeze to fit 20 of the little scamps onto Connor's circuit board, so he staggers them as illustrated below.


(Source: Connor Nishijima)

Another interesting point I hadn’t previously considered is that the RGB LEDs occupy only one half of the WS2812; the other half boasts the controller and package-to-package communications (they can be daisy-chained together). Thus, the slits in the plate mounted at the bottom of the Lixie are artfully arranged to sit directly over the LED portions of the WS2812s.


(Source: Connor Nishijima)

As I always say: "Show me a flashing LED and I'll show you a man drooling." Just one Lixie is entrancing; now imagine a system boasting lots of the little beauties.


(Source: Connor Nishijima)


(Source: Connor Nishijima)

Even better, imagine all the effects that you can achieve by varying the colors from digit-to-digit. I hadn’t even thought about this until I saw the image above.

Ha! I have an idea I bet even Connor hasn’t tried. This just came to me as I was savoring a dual-flavor tic-tac. What would happen if we were to set the pair of LEDs lighting each digit to be two different colors? I'll be trying this as soon as I've posted this column.

Now, I'm not suggesting that we start deploying Lixies in all of our systems (although that would look rather cool), but these large, bright digits may well offer a great solution in certain environments. Also, they cannot fail to add a certain pizzazz to one's hobby projects.

I now have a desire to build a Countdown Clock boasting 12 Lixie digits -- two each for the years, months, days, hours, minutes, and seconds, but -- once again -- that will be a story for another day.

The reason I'm waffling about all of this here is that I will be attending the forthcoming Embedded Systems Conference (ESC), November 8-9, in Minneapolis, and I plan on bringing a Lixie to show to my chums (and anyone else who doesn't get out of the way fast enough).

I'll also be presenting two sessions: Advanced Technologies for 21st Century Embedded Systems and Building an Artificial Brain. Happily, both of these talks will be in the ESC Engineering Theater, which means anyone can attend so long as they are flaunting a Free Expo Pass, but you do have to register. Hopefully I'll see you there. I'll be the one in the Hawaiian shirt. As always, all you have to do is shout "Max, Beer!" or "Max, Bacon!" to be assured of my undivided attention.

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