In which we meet the weird and the wonderful in vintage display space.
July 21, 2026
At a Glance
- CRT technology evolved far beyond TVs, spawning character generators, storage displays, and miniature numerical readouts.
- Nixie tubes, Dekatrons, and other display oddities demonstrate just how inventive twentieth-century engineers could be.
- Vacuum fluorescent displays combined the charm of vacuum tubes with the practicality that made them electronics superstars.
Over the past four installments in this mini-mega-series, we've wandered through well over a century of display technology (see Parts 1, 2, 3, and 4). We began with elegant analog meters and then progressed through ingenious electromechanical displays driven by gears, springs, relays, and solenoids. We explored scoreboards, split-flaps, flip-cards, flip-dots, and rotating prisms and finally arrived at the electronic era with segmented displays and our first encounter with vacuum fluorescent displays (VFDs).
I can’t help myself. I simply must show an image of a VFD again, as seen below. Their glorious blue-green, retro-futuristic fluorescent glow is like a siren song to me. As I may have mentioned, I’m currently working on a new implementation of my Chronological Contraption, whose purpose is to count the years, months, days, hours, minutes, and seconds to the commencement of my 100th birthday celebrations. Displaying this information will require 14 VFD tubes (YYYY MM DD hh mm ss).
VFD implementation of a 7-segment display. OSKAR (https://display-tubes.org/vfd/reflector-iv-12
Although VFDs have largely disappeared from mass-market consumer products, they have never completely vanished. Companies such as Noritake and Futaba continue to manufacture VFD modules for industrial and specialty applications. Happily, a surprisingly healthy supply of new old stock (NOS) tubes—many originating from Japanese, Soviet, and other Asian manufacturers—remains available to hobbyists.
One of the most popular VFDs among hobbyists is the Soviet-era IV-11, which continues to appear in countless retro clocks and DIY electronic projects. Several months ago, I purchased 20 of these little rascals. The circuit boards for the tubes (one per tube, so others can use as few or as many as they wish) are designed and on my desk, while the board for the power supplies (1.5 V, 5 V, and 25 V) is designed and on its way. I’ll tell you more about these tubes and this project in my next column. For the moment, however…
…no history of display technology would be complete without tipping our hats to some of the stranger branches of the family tree. Some were commercial successes. Some were technological dead ends. All of them remind us that engineers have never lacked imagination.
Meet the CRT oddballs
Most people think of cathode-ray tubes (CRTs) purely as television or computer displays, where an electron beam scans across the screen one pixel at a time. Not all CRTs followed this approach, however. Some of the more exotic members of the family took very different paths.
One of the most fascinating was the Charactron, which was developed in the early 1950s. Instead of drawing every letter from individual dots, a Charactron contained an internal metal stencil carrying the shapes of dozens of alphanumeric characters. By steering the electron beam through the appropriate aperture and then focusing the resulting image onto the screen, the tube could display complete letters and numbers almost instantaneously. Charactrons found homes in early computer terminals, military systems, radar displays, and air-traffic-control equipment long before modern graphics hardware became practical.
Closely related was the Typotron, which pursued a similar goal using a different internal architecture. Neither technology became commonplace—they were complex and expensive—but both represent ingenious attempts to coax ever more capability from the humble CRT.
Engineers also discovered that CRT technology could be miniaturized to produce numerical displays. Small CRT numerical readouts appeared in laboratory instruments, oscilloscopes, and frequency counters during the 1950s and 1960s, providing crisp, bright digits before LEDs became practical.
Perhaps the most charming of these miniature marvels was the Nimo tube. Superficially resembling a Nixie tube, a Nimo was actually a tiny cathode-ray tube. Rather than containing ten stacked metal cathodes, it used electrostatic deflection to steer an electron beam onto one of ten phosphor-coated numerals formed inside the envelope. The result was a brilliantly sharp, glowing digit that looked vaguely familiar while working in an entirely different way. Like so many technologies we've encountered in this series, Nimo tubes were ingenious, beautifully engineered, and ultimately overtaken by cheaper alternatives. For your edification and delight, you may wish to spend a few minutes watching a YouTube video titled The Nimo Tube: The Rarest and Most Dangerous Digital Display of All Time.
Another remarkable CRT-based invention was the Storage Tube, especially the Direct-View Storage Tube (DVST). Tektronix called its implementation the Direct-View Bistable Storage Tube (DVBST), which became by far the best-known commercial version.
Unlike a conventional CRT, which must redraw the entire image many times each second, a DVST stored the image within the tube itself, allowing it to remain visible indefinitely without refreshing (provided power was maintained). This made the technology particularly attractive for early computer-aided design (CAD) systems and scientific graphics terminals, where it produced exceptionally sharp, flicker-free line drawings. The downside was that modifying even a small part of the image usually meant erasing the entire screen and redrawing everything.
A cabinet of curiosities
Not every display technology fits neatly into a family tree. Some seem almost to have appeared from nowhere, cheerfully ignoring whatever everyone else was doing.
One interesting example is a lightguide display, also known as an edge-lit display. Instead of illuminating a character's face directly, these devices injected light along the edge of an acrylic or glass numeral. Internal reflections carried the light through the material until it escaped from carefully engraved surfaces, causing the entire digit to glow with surprising uniformity. The effect was elegant, almost magical, and remains popular today in decorative clocks and signs. Modern hobbyist examples include Jürgen Grau’s dotted numeric displays and Connor Nishijima’s Lixie Displays.
Then there were Dekatrons. Strictly speaking, these weren't designed as displays at all, but as decade-counting tubes. A glowing gas discharge stepped around a ring of ten cathodes under electronic control, visibly advancing from one position to the next as pulses arrived. Engineers quickly realized that what made an excellent counter also made a wonderfully animated numerical indicator. Watching a Dekatron count is oddly hypnotic—rather like observing a tiny neon merry-go-round.
The magic of Nixie tubes
Few vintage displays inspire as much affection today as the Nixie tube. Introduced in the 1950s, a Nixie contains ten intricately shaped wire cathodes stacked one behind another inside a neon-filled glass envelope. Applying around 170 volts to the selected cathode strikes the gas discharge, while the voltage can then be reduced to roughly 140 volts to keep the digit glowing. The result is one of the most beautiful displays ever created: warm orange numerals that appear to float in space.
Nixie tubes come in all sorts of shapes and sizes. Arguably, the most beautiful incarnation was the German Z568M. Manufactured by companies like Siemens/Telefunken/RFT in the 1970s, this bodacious beauty was approximately 2 in. (50 mm) in diameter and 4 in. (100 mm) tall.
Most surviving Nixie tubes are available only as NOS or salvaged from old equipment. However, my friend Dalibor Farny and his team in the Czech Republic have revived the art of Nixie manufacture, handcrafting around 50 tubes each week. Their flagship product, the R|Z568M (the ‘R’ stands for “Resurrection”), is pin-compatible with the original Z568M.
The image below shows my ongoing Nixie tube clock project fitted with bespoke tubes created by Dalibor. To the best of my knowledge, it features one of only two sets of steampunk R|Z568M tubes in the world, proudly flaunting their copper anode cages and shiny bronze bases.
Steampunk Nixie tubes are the best of all. CLIVE “MAX” MAXFIELD
Nixies have enjoyed an extraordinary renaissance among hobbyists, artists, and collectors. There is something almost magical about those floating digits that no photograph quite manages to capture. Unfortunately, their beauty came at a price. Their relatively high operating voltages, delicate glass envelopes, and comparatively expensive manufacturing processes made them increasingly difficult to justify as electronic technology advanced.
And then came VFDs
Although vacuum fluorescent displays also employed vacuum-tube technology, they solved many of the problems that plagued their Nixie cousins. Instead of requiring around 170 volts to strike a gas discharge, most VFDs operate with an anode and grid supply of only about 20 to 30 volts (plus a low-voltage filament supply). They are substantially brighter, making them much easier to read in daylight, and their segmented construction allows engineers to create not only numeric displays, but also alphanumeric characters, icons, bar graphs, and almost any custom geometry they can imagine.
VFDs also proved easier to manufacture and generally less expensive than comparable Nixie displays. Consequently, they rapidly found their way into everything from microwave ovens and video cassette recorders to hi-fi systems, cash registers, automotive dashboards, and laboratory instruments. By the 1970s and 1980s, the distinctive blue-green glow of a VFD had become one of the defining visual signatures of consumer electronics.
Even VFDs, however, could not escape the relentless march of progress. As high-brightness LEDs became less expensive and LCDs matured, these newer technologies offered lower operating voltages, lower power consumption, greater ruggedness, and lower manufacturing costs. By the 1990s, they had displaced VFDs from most mass-market products, leaving them to continue their lives in industrial equipment, specialty applications, and—much to my delight—the workshops of hobbyists and retro-computing enthusiasts like your humble narrator (I pride myself on my humility).
Next time
In my next column, I’ll introduce you to VFDs in sufficient detail that you’ll hopefully be enthused to start using them in your own projects. Until then, as always, please feel free to email me at [email protected] with any comments, questions, or suggestions.