The ZM1040 is a large Nixie tube produced by various European manufacturers, with this particular unit made by Valvo. Tesla, a Czechoslovakian manufacturer, produced a version of the ZM1040 that featured a square anode grid, setting it apart from the one shown here. To enhance contrast and filter out blue light emitted by the included mercury vapor, the tube is covered with a red filter. A variant without this filter was also available under the designation ZM1042.

The DGM01 is a modern Nixie tube produced by Sadudu and his company iNixie LAB in China, comparable in size to the Soviet IN-18. Like the R|Z568M by Dalibor Farný, the DGM01 is assembled by hand in small quantities. Each digit in the tube has a distinctive design, with the numbers one and five standing out in particular. Notably, the DGM01 features a right decimal point which is unusual for tubes of this size and was specifically incorporated for use in replicas of the Divergence Meter from the popular anime series Steins;Gate. Unlike the R|Z568M and tubes made by Millclock, which have a large metal bases, the DGM01 utilizes proper pin-to-glass seals, enhancing its authentic appearance. The glow discharge exhibits the characteristic blue tint seen in tubes containing mercury vapor, which is indicative of long-life Nixie tubes.

The CD66A, produced by NEC in Japan, is a medium-sized Nixie tube capable of displaying all ten digits along with a right decimal point. It features a distinctive anode design made up of multiple horizontal wires, differing from the typical hexagonal or square grids stamped from sheet metal in most Nixie tubes. A variant of the CD66 with a left decimal point was also available. Additionally, the CD66A is pin-compatible with the European ZM1242, which has a more conventional design.

The B-7971 is a very large alphanumeric display tube developed by Burroughs, originally designed for use in stock tickers. Unlike regular Nixie tubes with numerals arranged on a stack, the B-7971 contains 14 individual segments that can be combined to display every letter of the English alphabet as well as the digits 0 through 9. An additional segment in the bottom can be used to display an underscore.

Known for its exceptional longevity, with later models—distinguished by an “antenna” on the anode cage—supposedly lasting even longer, the B-7971’s has become a popular choice among collectors for creating large Nixie clocks. Since the tube’s total current draw varies with the number of segments lit, a single anode resistor cannot effectively limit the current. Instead, each cathode must be connected to its own resistor. The datasheet suggests using different resistor values for different segments to ensure uniform brightness. The most frequent failure mode of a B-7971 appears to be two or more cathodes shorting together. This may occur due to physical impact or the tube being overdriven for prolonged periodes of time. New old stock of B-7971 tubes is virtually nonexistent, as nearly all units available today have been salvaged from the aforementioned stock tickers.

The N4 is a neon-filled decadic counting tube produced by the German company DGL Pressler (Deutsche Glimmlampen GmbH), mostly known for their special tubes. It functions in a unidirectional, single-pulse mode, with each of its ten stable cathodes accessible via separate pins. According to its datasheet, the tube is capable of up to 25,000 counts per second, making it exceptionally fast for a neon-filled Dekatron.

This unit’s glass envelope is covered with a silver coating likely intended to reduce light bleeding in from the sides affecting readability. Unlike the tiny pins typically used as cathodes in Dekatrons, the N4 features small plates, which give the discharge a noticeably wider appearance. Images of a transparent version, available here, reveal that the tube’s interior is almost empty, explaining its unusually light weight. A variant of the tube featuring a smaller phenolic base was also produced under the designation N3.

The GC12/4B is a neon-filled counting tube manufactured by ETL in Great Britain, capable of bi-directional operation and up to 4,000 counts per second. It features twelve stable cathodes, unlike the usual ten found in most Dekatrons, allowing it to count in base-12. Four of these cathodes are connected to output pins, enabling them to trigger actions such as advancing another Dekatron when active. Divide-by-12 Dekatrons like the GC12/4B were ideal for timekeeping applications since the division of hours, minutes, and seconds in a day aligns with multiples of twelve.

This document released by Mullard explains the operating principles of glow discharge tubes and their internal construction. Additionally, it includes schematics for various applications, beginning with a simple static display and progressing to two different approaches for implementing a multiplexed display. In addition to describing the anode-scanning method, which is the most widely used approach today, it also presents an alternative cathode-scanning technique and discusses the various drawbacks associated with this method.

The XN1 is an early Nixie tube produced by Hivac in Great Britain and Lorenz in Germany. The earliest documentation referencing this tube I could find is dated September 9, 1961, shortly after the invention of Nixie tubes. This particular unit features an evaporative getter at the top, giving it a distinctive appearance typically associated with vacuum tubes (often seen in VFDs). However, versions with a getter located behind the anode cage were also manufactured. The tube’s anode cage is notably restrictive, limiting visibility to mostly straight-on angles. Unlike many other tubes of similar size, the XN1 does not include any decimal points.

The E1T is a decadic counting tube developed by Philips, predating the invention of gas-filled Dekatrons. Each pulse advances the tube’s internal count by one and generates a voltage spike, which can be used to trigger specific actions. Internally, the E1T operates as a small cathode ray tube with a ribbon-shaped electron beam that occupies one of ten stable positions. The current position of the beam is indicated as a glowing strip, with each position marked with its corresponding value on a piece of film affixed to the tube’s glass envelope. The tube’s envelope is coated with a transparent protective layer, which is prone to cracking over time, particularly in damp environments. Consequently, E1Ts in pristine condition have become increasingly rare.

The DR2010 is a Numitron developed by RCA, with units sold under the Apollo brand by IEE bearing the same model numbers but substituting “DR” with “DA”. The DR2010 is identical with the DR2000 except for the latter lacking a decimal point. As shown below, some units feature a flat top, while others have a convex top. This seems to be a manufacturing variation and does not necessarily correspond to different model numbers.

With its 40mm digits, the IN-18 (“NH-18”) is the largest Nixie tube mass-manufactured in the Soviet Union. It shares the same envelope diameter with smaller Nixie tubes, such as the ZM1040 and Z566M, which gives the IN-18’s digits a slightly elongated appearance. Today, the IN-18 is among the most popular Nixie tubes, often used in large Nixie clocks. Although vast quantities were manufactured and remain readily available on online marketplaces like eBay, IN-18 tubes have become quite expensive. Unlike many Soviet Nixie tubes, the IN-18 features a proper cathode for the number five rather than an inverted two. Its gas mixture includes trace amounts of mercury vapor, which significantly extends the tube’s lifespan and imparts a faint bluish tint to its glow.

The IN-1 (“NH-1”) is the first generation of Nixie tube mass-produced in the Soviet Union by Anod. Like many other Soviet Nixie tubes, the IN-1 utilizes an inverted two to represent the number five, although at least some earlier models featured a proper five. This tube is notable for its large phenolic base, with each pin conveniently numbered. As is typical of early Nixie tube designs, the IN-1’s gas mixture lacks mercury vapor, which results in reduced longevity. It is, however, pin-compatible with and visually very similar to the Dolam LC-516, which could be considered as a longer-lasting alternative for those who appreciate the IN-1’s UFO-like design. Original U11 sockets are notoriously difficult to come by so building a device using either of them would likely require coming up with a custom made socket design.

The GN-2 is a large Nixie tube produced by STC as part of their ‘Nodistron’ line of display tubes. It is pin-compatible with and the direct successor to the GN-1 and already shows notable advancements in Nixie tube manufacturing. Unlike its predecessor, the GN-2 features digits stamped from sheet metal instead of ones made from bent wire. These digits are arranged in a more compact stack, separated by insulating rings. The thick wires previously used to connect the numerals to their corresponding pins have been replaced with the thinner leads seen in most later top-viewing Nixie tubes. Additionally, the GN-2 no longer employs evaporative getters and the pin connected to the anode meant for operation with rectified AC voltage on the GN-1 is now marked as NC in the tube’s datasheet. The tube’s numerals emit the same distinctive orange glow seen in the GN-1, indicative of a mercury-free production process suggesting a relatively short operational lifespan.

The IV-17 (“NB-17”) is a medium-sized sixteen-plus-two segment VFD tube manufactured in the Soviet Union by Reflector, known today as Sovtek. Unlike the IV-12 seven-segment tube, the IV-17 can display all letters of the English alphabet in addition to the numbers zero through nine. Sixteen segments are dedicated to displaying characters, while the remaining two are used for the left and right decimal points. The character set used in the photos below is based on the one suggested by the datasheet of the Burroughs B-7971 sixteen-segment Nixie tube.

The IV-12 (“NB-12”) is a large seven segment VFD tube produced in Soviet Union by Reflector (known today as Sovtek). It closely resembles the IV-11 but lacks a decimal point and has solid pins instead of flying leads. This allows the tube to be installed in a common 10-pin socket still being produced in China. Like most VFD tubes, the IV-12 includes a grid that can be negatively charged to interrupt electron flow without disabling the filament. This capability allows for multiplexed operation (see schematic shown below) and effectively turns the tube into a triode.

The 6E5 is one of the earliest examples of a magic eye tube, invented in 1932 by American electrical engineer Alan DuMont. Designed as a cost-effective alternative to expensive needle indicators, it was intended for use in devices like radios that required user tuning without high precision. The first commercially available 6E5 tubes, sold by RCA starting in 1935, featured a coke-bottle-shaped glass envelope common in early vacuum tubes.

Unlike more modern magic eye tubes, the 6E5 has a relatively simple display characteristic, consisting of a single shadow that expands or contracts based on the supplied input voltage.

The GR-211 is a large Nixie tube produced by Rodan-Okaya in Japan. It ranks as the third-largest Nixie tube made by Rodan and succeeded the short-lived GR-11. Later models were rebranded as CD94. Notably, the GR-211 includes a left decimal point, which is uncommon for tubes of its size. In devices using larger Nixie tubes, a separate neon bulb typically represented the comma instead. Interestingly, the datasheet marks the decimal point’s pin as “not connected.”

The Tesla 11TU7 is an early neon-filled Nomotron counting tube allowing for up to 20,000 counts/second. It operates in a unidirectional, single-pulse mode, advancing the discharge by one position with each pulse and featuring ten stable positions. Unlike conventional decadic counting tubes (Dekatrons), its guiding electrodes are concealed behind a metal shell. Only the stable cathodes are visible through circular openings, each marked with its corresponding value on a transparent mica shield.

The R|Z568M is a massive modern Nixie tube produced by Dalibor Farný and his company. Each tube is manufactured by hand in the Czech Republic. As the name suggests, its design is meant to be reminiscent of the Z568M, the largest Nixie tube produced in the GDR. A picture below shows a comparison between the R|Z568M, an original Z568M, and a Z566M. Despite being the smallest of the three, the Z566M, with its 30mm digit height, is still considered a large tube. This makes the impressive scale of the R|Z568M, featuring 50mm digits, even more striking. The manufacturing process of an R|Z568M tube is documented in this video.

The DTF104B is a Numitron display tube produced by RCA. Internally, it is nearly identical to the more common DR2000 and similar to the DR2010, but it is designed to be read from the top rather than the side. A spot exists on the backplate where a left decimal point could have been included, but it lacks filaments and is therefore non-functional on this model. Its flat top gives the DTF104B a distinct look and helps reducing reflections from adjacent tubes.

This document provides information on STC’s GN-1 Nixie tube. It includes a datasheet outlining the electrical specifications for both DC and rectified AC operation, as well as mechanical details such as tube dimensions and digit height. Additionally, it features circuit diagrams illustrating how the tube can be used in conjunction with the G10/241E counting tube. This document describes a very early version of the GN-1 without an anode grid. Later units included one, likely to achieve more even illumination.

When the Nixie tube was introduced in the 1950s, it faced a significant drawback: its driving circuitry required transistors with relatively high breakdown voltages capable of handling the elevated operating voltages. At the time, such transistors were not widely available. This limitation created a demand for an alternative display technology that could operate with low-voltage, low-current logic circuitry. The solution was the Pixie tube, initially designated as the Z550M and later renamed the ZM1050.

The Z566M is a large Nixie tube manufactured by RFT. It is pin compatible with the ZM1040 but differs in design, featuring a flatter top and a top-evacuation design, though some earlier units were evacuated from the bottom. In some instances, Z566Ms have even been rebranded and sold as ZM1040s (see picture at the end of this page). A variant without the pre-applied red filter was marketed as the Z5660M.

The Z566M was primarily utilized in laboratory equipment such as voltmeters and frequency counters. Its large size also made it well-suited for devices designed for use in educational settings, such as schools. A Nixie tube featuring various symbols, designed to complement the Z566M/Z5660M, was marketed under the names Z567M and Z5670M.

The MG-19B is a tiny, segmented neon-filled display tube produced by Rodan and marketed under the Elfin brand, designed for use in small electronic instruments. It features two additional diagonal segments, enabling it to display the digits ‘1’ and ‘7’ more naturally, as well as certain other alphanumeric characters. The tube also includes a right decimal point. Unlike Nixie tubes, each cathode in the MG-19B requires an individual resistor, as the current needed varies with the number of illuminated segments. With a 180V breakdown voltage and a recommended 230V anode voltage, the tube operates at significantly higher voltages than most Nixie tubes. This made driving the MG-19B more complex, as affordable high-voltage transistors were not readily available when the tube was introduced.

This document details the design, functionality, and application of the STC G10-241E Nomotron, a unidirectional single pulse counting and display tube. It describes its operation and highlights its applications in areas such as tachometry, counting and batching, and frequency and time measurement. Besides a general overview over its mechanism of operation, it also contains detailed diagrams of the tube and example circuits for many of its aforementioned use cases.

Detail pictures of the G10/241E can be found here.

The LC-516, produced by Polish tube manufacturer Dolam (later known as Unitra Dolam), is pin-compatible with and visually similar to the Soviet IN-1 Nixie tube. However, unlike the IN-1—an early model with a relatively short lifespan—the LC-516 is mercury-doped, significantly enhancing its durability and giving its glow a subtle bluish tint. The LC-516 features a slightly smaller glass envelope and digits compared to the IN-1; a comparison between the two is shown below. Additionally, Dolam manufactured a version without the phenolic base, designated as the LC-513.

The National Union GI-10 is likely the first Nixie tube ever produced, belonging to National Union’s Inditron series of display tubes. Patented applied for in 1954 (and granted in 1956), it predates the original “NIXI” tube developed by Haydu Brothers and later Burroughs by at least a few months. Similar to other early Nixie tubes, such as the STC GN-1, its digits are not stamped from sheet metal but are crafted from wire. These digits are connected to the tube’s 10 pins via long rods covered in an insulating layer of ceramic that also serve to hold them in place. In contrast to more modern Nixie tubes, where the digits are arranged to minimize obstruction of each other, the digits in the GI-10 are organized in a straightforward, sequential manner. The zero digit is positioned at the very front, while the one is located at the farthest point in the stack. Unlike most later Nixie designs, the GI-10 lacks a dedicated anode; instead, activating a specific digit requires all other electrodes to be held at anode potential, which complicates the driving circuitry and makes it difficult to achieve uniform brightness across all digits. The tube uses a standard Noval 9-pin socket with an additional central pin.

English title: Notes on the use of indicator tubes

This document contains information on various East German display tubes and examines their respective areas of application as well as their advantages and disadvantages. In particular, the different operating modes of Nixie tubes are discussed. At the end of the document the technical data of some common Nixie tubes can be found.

The content of the booklet differs from that of the similarly titled “Hinweise zur Anwendung von Anzeigeröhren - Sonderausgabe 3/1968”.

English title: Notes on the use of indicator tubes - Special issue 3/1968

This document contains an excerpt from the magazine “radio und fernsehen” (“radio and television”), published in the GDR, which discusses the use of various East German display tubes, with a particular focus on the Z570M and Z870M. It was released by RFT in March 1968.

The content of the booklet differs from that of the similarly titled “Hinweise zur Anwendung von Anzeigeröhren”.

The GR10H is an early Nixie tube produced by ETL, featuring digits visible through a small viewing window, with the majority of its envelope coated in black paint—likely intended to enhance contrast and minimize light bleed from adjacent tubes. Shown at the end of this page is a transparent GR10H revealing that, like in the STC GN-1, the digits are connected to the tube’s pins via thick wires and an evaporative getter was used.

The STC G10/241E is an early neon-filled Nomotron counting tube allowing for up to 20,000 counts/second. It operates in a unidirectional, single-pulse mode, advancing the discharge by one position with each pulse and featuring ten stable positions. Unlike conventional decadic counting tubes (Dekatrons), its guiding electrodes are concealed behind a metal shell. Only the stable cathodes are visible through circular openings, each marked with its corresponding value on a transparent mica shield.

The OmniRay SAO M 40 is a so-called Sphericular Optic Display. While similar in both appereance and operation to projection displays like the IEE one-plane readout, the theory behind the M 40 is vastly different. It employs the principle of geometric optics to produce a character on a flat viewing screen. The screen area is subdivided into more than a thousand tiny convex lenses, each focusing light from its specific focal plane. Characters are displayed by illuminating only certain sections of the screen from different angles, which selectively allows light to pass through areas, producing a character composed of many tiny dots. A comprehensive explanation of the operational theory behind this device is available in the description of a similar model manufactured by Burroughs, accessible via the link provided below.

The GN-1, manufactured by STC and sold under the name ‘Nodistron’, was among the earliest commercially available Nixie tubes. The oldest documentation I could locate dates back to December 1959 (referenced below). The tube’s design reflects its age, with the digits being formed from wire rather than stamped from sheet metal like in most later Nixies. The GN-1 emits a distinctly orange glow, indicative of a mercury-free design, which likely results in a shorter lifespan compared to later models. Unlike more modern Nixie tubes, the GN-1 includes two evaporative getters, clearly visible on the left and right sides of the glass envelope. Additionally, its numerals are not mounted on a metal pin insulated by spacers but are instead secured between two mica plates and connected to the tube’s pins via thick wires. Interestingly, according to the datasheet, the tube has two anodes for use with direct and alternating currrent respectively.