I’m constantly amazed by the ingenuity of early electrical, electronic, and mechanical engineers, especially in the context of the weird and wonderful display technologies they conceived and created. I have to admit to having a soft spot for electromechanical constructions, such as split flap displays (see Roll Your Own Split Flap Displays), but my true love is displays that light up in one form or another. As I always say, “Show me a flashing LED, and I’ll show you a man drooling.” Sometime circa 2014, I was working on an Arduino screw terminal shield Kickstarter project with my chum Duane Benson when I received an email from Steve Manley in the UK. Although Steve was originally reaching out about the shield, we soon discovered that we shared a common interest in light effects and LED displays. In a series of articles and YouTube videos, Steve ended up documenting the design and construction of an 8 x 8 x 8 tricolor LED cube and of an amazing LED-based clock. Also circa 2014, I ran across the steampunk Nixie tube clocks created by Paul Parry at Bad Dog Designs. In turn, Paul introduced me to Pete Virica at PV Electronics who creates the circuit boards for these clocks, Dalibor Farny who handcrafts Nixie tubes in the Czech Republic, and Andy and Mandy Blackett at Engraving Studios who create the brass panels Paul uses in his designs. As I noted in my World’s First Nixie Tube Clock? column, I found a short History of Nixie Tubes offering on the Steampunk Alchemy website along with a very interesting The Nixie Tube Story article on the IEEE Spectrum website. Until reading these articles, I was under the impression that Nixie tubes originated in the 1950s — I was unaware that precursor Nixie tube technologies were around as early as the 1930s.
A LED-based Lixie display (Click image to see a larger version — Image source: Connor Nishijima)
In the summer of 2017, I ran across the tricolor LED-based Lixie displays created by Connor Nishijima. A Lixie display comprises ten thin acrylic sheets, each of which is laser-etched with a numeral. Conner told me that he dismantled a defunct Nixie tube to obtain the font he used for his numerals (he started with a single line, but soon moved to the dual line version shown here). Slotted mounting plates on the top and the bottom hold everything together, A circuit board containing 20 NeoPixels (two per digit) is located under the lower mounting plate. With a display area of around 2.5” wide by 4” tall, these really do look rather amazing. In fact, as you can see in this video, I decided to use 12 of these little beauties to implement my Countdown Timer, whose job it is to display the years (YY), months (MM), days (DD), hours (HH), minutes (MM), and seconds (SS) remaining until the commencement of my 100th birthday celebrations in May 2057 (mark your calendar now). When I saw my first Lixie display, my knee-jerk reaction was that these little rascals were 21st century reincarnations of Nixie tubes. But then my chum Steve Leibson pointed me at a rather interesting article regarding the First Digital Voltmeter (DVM), which was introduced to the market in 1953. The reason I mention this here is that this unit employed a new type of display based on thin slices of Lucite that were etched and illuminated by tiny incandescent bulbs located on their edges. When you discover stuff like this, it’s hard not to be reminded of Ecclesiastes 1:9, which informs us: “That which has been is what will be, that which is done is what will be done, and there is nothing new under the sun.” Whoever wrote Ecclesiastes, one gets the strong impression that he wasn’t a party animal and probably didn’t receive invitations to too many celebrations, but we digress… Whenever I hear mention of a seven-segment display, I cannot help but think of LED-based implementations (see also nine-segment, fourteen-segment, and sixteen-segment displays). (I also think of the Awesome Clock implemented using 144 seven-segment displays, but we don’t have the time to talk about that here.) According to Wikipedia, however, “Seven-segment representation of figures can be found in patents as early as 1903, when Carl Kinsley invented a method of telegraphically transmitting letters and numbers and having them printed on tape in a segmented format.”
Image from George Lafayette Mason’s patent (Click image to see a larger version)
“Ah,” you say, “but that was a printed form.” “Ah Ha,” I respond, “but I haven’t finished yet.” A few days ago, I was touching base with Steve Manly (who we met earlier) when he told me he was part of a group working on a rather interesting project regarding a modern tricolor LED implementation (a resurrection, if you will) of 21-segment Victorian displays. Well, color me intrigued (no pun intended). It turns out that Paul Parry (who we also met earlier) and Steve are part of the Smartsockets Group on Groups.io Chris Barron started the Smartsockets group in 2006. It wasn’t long before Chris was joined by John Smout, and together they act as co-moderators for the group. Chris told me that he wanted to use some Nixie tubes as the basis for his own clock/data display. He also wanted to include some effects, like fading individual digits, but this wasn’t easy with his existing multiplexed display. Due to the issues he was running into, Chris came up with the Smartsockets concept, which is based on a separate driver for each digit. Through the use of simple ASCII-type instructions and industry-standard protocols — coupled with built-in fonts and transition effects — it is possible to use Smartsockets to produce arrays comprising many display devices of similar and different types. There are many different aspects to this group, which I immediately joined. For example, John and Chris are currently creating RGB LED Smartsockets using a PIC microcontroller on the back of each display. Meanwhile, Richard Scales is creating a much larger Neon version, also using PICs in a similar way. For myself, the facet of this group that intrigues me the most is their current interest in 21-segment displays. It seems that someone called George Lafayette Mason filed his patent for these displays in 1898. The original versions of these bodacious beauties involved 21 small incandescent bulbs (one per segment) all controlled by a complicated mechanical switch that could activate various groups of segments as required to represent the different characters.
Renderings of 3D printed shell and PCB for 21-segment display (Click image to see a larger version — Image source: Steve Manley)
When John ran across this 21-segment concept, he decided to add an RGB LED version of this display to the Smartsockets portfolio. As part of this, John created the original DXF drawings along with the STL model for 3D printing the shell, which he kindly shared with other members of the group, including Steve. John also created a printed circuit board (PCB) design that includes a PIC in addition to the LEDs and supporting components. Now, I think the Smartsockets concept is a great idea, but I’ve never really been a PIC man myself. Like Steve and Paul, most of my designs involve a single Arduino (or similar) microcontroller development board driving a bunch of WS2812B tricolor LEDs, so that’s the way we’re going to go. Steve has a black belt creating circuit boards using the EasyEDA PCB design software and 3D models using Autodesk’s Fusion 360 integrated CAD, CAM, and CAE suite. The bottom line is that Steve has created his own PCB and 3D-printed shell designs for the 21-segment displays. Each character, which is 50 mm wide by 64 mm tall, has 35 tricolor WS2812B-2020 LEDs — one each for the seven smaller segments and two each for the fourteen larger segments.
A fully illuminated 21-segment digit from the Aresluna.org tool (Click image to see a larger version)
Steve also pointed me toward the Aresluna.org website where they have an incredible online tool that you can use to view existing fonts and design your own fonts for different displays. There are two main pages: “Produced” and “Expr’tal” (which I assume stands for “Experimental,” but I could be wrong). Whichever page you are on, select one of the display types to receive a small description, then start typing on your keyboard to see that character displayed. But wait, there’s more, because as you move your mouse cursor over different segments, they turn white. Clicking on a segment will toggle it on and off, thereby allowing you to see what your own characters will look like. When you are ready, make sure you are on the “Expr’tal” page and select the 21-segment display option. This is the Victorian display we are talking about here. What? You want to see what they look like “in the flesh,” as it were? Well, Steve is currently experimenting with different techniques to prevent light bleeding across adjacent segments. Take a look at this video showing three 21-segment digits running a FastLED library example.  
Personally, I prefer the implementation in the middle with the wider segments. That’s the style I’m planning on using myself. Initially, I wanted to create a 12-column by 6-row array of these characters, but I simply don’t have the funds at the moment. Instead, I’m going for a single row of 10 characters. The PCBs are being manufactured as we speak (I’m desperately trying not to squeak in excitement). What can you do with 10 characters? Well, as a starting point, we can display the time in a HH.MM.SS format with two characters left spare (we could use one to display ‘A’ or ‘P’ and the other as a space). I have a bunch more ideas, but we will save those for another day. I have to say that the members of the Smartsockets group have been incredibly gracious. Right from the beginning, Steve asked them if they minded him telling me what was going on and they replied that there wasn’t a problem. Later, when I joined the group, they said they were happy for me to write this column and spread the good word. They’ve also shared all sorts of useful information. For example, I originally thought of these displays as being Edwardian on the basis that George Mason’s patent was finally granted in September 1901, by which time King Edward VII had ascended to the throne (Queen Victoria passed away in January 1901). However, John explained that since Mason filed his patent in 1898, their conception was firmly placed in Victorian times. Similarly, in addition to telling me the history of Smartsockets, Chris pointed me at an interesting article and video from 2007 showing a piece of word art created by Matt Gorbett that was based on a V1 Smartsocket implementation.  
Observe that there are 10 characters (including the two spaces) in Matt’s piece. “Good Golly Miss Molly,” this will fit on my own 10-character display (when I build it). In my case, however, I’m going to include a potentiometer with an antique knob under every one of my characters (“just in case”). I must admit that I’m rather excited to see these displays in action. I know from my own videos of my 12 x 12 ping pong ball array that these things look so much better when you are looking at them with your own eyes. I will, of course, be reporting further in future columns. In the meantime, as always, I appreciate you comments, questions, and suggestions.