When they were invented in the 1950s, Nixie tubes were a huge leap forward in display technology. In the days before affordable LEDs made seven-segment displays a commodity, there were few alternatives to the charming glow of the clear and legible characters inside Nixies. Sturdy and reliable, the cold-cathode displays found their way into everything from scientific instruments to test equipment, and even some of the earliest computers and the equipment that formed the foundation of the Space Race sported the venerable tubes.
But time marches on, and a display that requires high voltage and special driver circuits isn’t long for a world where LEDs are cheap and easy to design with. Nixies fell from favor through the late 1960s and 1970s, to the point where new tubes were only being made by the Russians, until that supply dried up as well. Rediscovered by hobbyists for use in quirky clocks and other displays, any stock left over from the Nixie’s heyday are quickly being snapped up, putting the tubes on the fast track to unobtainium status.
That’s not to say that you can’t get brand new Nixie tubes, of course. Artisanal manufacturers like Dalibor Farný have taken the Nixie to a whole new level, with big, beautiful tubes that are handcrafted from the best materials. Reviving the somewhat lost art of Nixie manufacturing wasn’t easy, but the tubes that Dalibor makes in a castle in the Czech Republic now find their way into cool clocks and other builds around the world. He’ll join us on the Hack Chat to dive into the art and science of Nixies, and what’s going on with his mysterious “Project H”.
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The project consists of an 8×48 matrix display constructed out of INS-1 (ИНC-1) tubes. These tiny neon tubes are 6.5 mm in diameter, showing a bright orange dot of light when powered up. Requiring just 100 V and 0.5 mA to light, they’re a touch easier to drive than the famous Nixie.
[Pierre] decided to go all out, wishing to replicate the capabilities of smart LEDs like the WS2812. These contain a microcontroller built in to each LED, so [Pierre] would have to do the same. Each of the 384 neon tubes got its own bespoke PCB, containing a PIC16F15313 microcontroller, step up voltage circuitry, and a 6-pin connector. (Whoah!) When each bulb was soldered to its PCB, they were then plugged into a backplane. An ESP32 was then employed to drive the display as a whole.
Creating a display in this fashion takes a huge amount of work, with most of it being soldering the 384 individual bulb PCBs containing 11 components each. We have a lot of respect for [Pierre]’s work ethic to get this done during lockdown, and the final result is a gloriously retro neon matrix display. We’ve featured other neon matrixes recently, too. Video after the break. Continue reading “384 Neon Bulbs Become Attractive Display”→
The low-cost LED has changed the way we approach lighting in all its forms, allowing complex addressable displays and all sorts of lighting goodness. But what did we do before we had cheap LED arrays? Use neon bulbs, perhaps? That’s exactly what [Manawyrm] has done with his chainable 8×8 neon matrix boards, taking 64 neon indicator bulbs and driving each from mains potential with an individual triac. A line of 74HC595s handle the data transfer, floating at mains voltage while their ESP32 driver is kept safe by a set of isolators.
Neons have generally featured here as novelties rather than as significant displays in their own right. They’re interesting components that everyone should have a play with, not least because the possess negative resistance, and can be made to oscillate.
No matter what you think about Nixie tubes, you’ve got to admit that having a Nixie custom made for you would be pretty cool. The cost of such a vanity project is probably prohibitive, but our friends at Keysight managed to convince none other than [Dalibor Farný] to immortalize their logo in glass, metal, and neon, and the results are beautiful.
Nixie aficionados and lovers of fine craftsmanship will no doubt be familiar with [Dalibor]’s high-end, hand-built Nixie tubes, the creation of which we’ve covered before. He’s carved out a niche in this limited market by turning the quality far above what you can find on the surplus Nixie market, and his custom tubes grace sleek, distinctive clocks that really make a statement. Bespoke tubes are not a normal offering, but he decided to tackle the build because it gave him a chance to experiment with new methods and materials. Chief among these are the mesh cathodes seen in the video below. Most Nixies have thin cathodes for each character cut from solid sheet metal. The elements of the Keysight logo were skeletonized, with a solid border and a hexagonal mesh infill. We’d have loved to see the process used to create those pieces — laser cutting, perhaps?
The bulk of the video is watching the painstaking assembly process, which centers around the glassblower’s lathe. It’s fascinating to watch, and the finished, somewhat out-sized tube is a work of art, although part of the display seems a little dark. Even though, [Dalibor] needs to be careful — plenty of outfits would love to see their logo Nixie-fied. Wouldn’t a Jolly Wrencher tube look amazing?
Joule thief are small, fun circuits which exploit a few characteristics of electronics and LEDs in order to “steal” virtually all of the energy stored in a battery. They can operate at incredibly small voltages and are fairly simple to make. With a few modifications to this basic circuit it’s possible to drive other things than an LED, though, like this joule thief that lights up a neon bulb.
The circuit from [suedbunker] aka [fuselage] is based on a pin from the Chaos Communication Camp which had a standard LED. To get a neon light to illuminate a few modifications to the standard joule thief are needed.
First, the windings have to be changed from 10:10 to 10:80 to increase the voltage across the bulb. Second, a transistor with slightly different characteristics was used than the original design. The capacitor was also replaced with a larger one.
While it might seem simple, the physics of how a joule thief works are anything but, and modifying the delicate circuit to work with something other than an LED is commendable. It also has a steampunk vibe which is a cool look even in projects that don’t involve steam at all.
Everyone knows that one of the coolest things to do with a Tesla coil is to light up neon or fluorescent tubes at a distance. It’s an easy and very visual way to conceptualize how much energy is being pumped out, making it a favorite trick at science museums all over the world. But what would it look like if you took that same concept and increased the resolution? Replace that single large tube with an array of smaller ones. That’s exactly what [Jay Bowles] did in his latest video, and the results are impressive to say the least.
From a hardware standpoint, it doesn’t get much simpler. [Jay] knew from experience that if you bring a small neon indicator close to a Tesla coil, it will start to glow when approximately 80 volts is going through it. The higher the voltage, the brighter the glow. So he took 100 of these little neon bulbs and arranged them in a 10×10 grid on a piece of perfboard. There’s nothing fancy around the backside either, just all the legs wired up in parallel.
When [Jay] brings the device close to his various high-voltage toys, the neon bulbs still glow like they did before. But the trick is, they don’t all glow at the same brightness or time. As the panel is moved around, the user can actually see the shape and relative strength of the field by looking at the “picture” created by the neon bulbs.
The device isn’t just a cool visual either, it has legitimate applications. In the video, [Jay] explains how it allowed him to observe an anomalous energy field that collapsed when he touched the base of his recently completed Tesla coil; an indication that there was a grounding issue. He’s also observed some dead spots while using what he’s come to call his “High-Voltage Lite-Bright” and is interested in hearing possible explanations for what he’s seeing.
With the popularity of Nixie clocks, we’d be forgiven for thinking that the glowing tubes are only good for applications with a stately pace of change. But we forget that before they became the must-have hobbyist accessory, Nixies were used in all kinds of scientific instruments, from frequency counters to precision multimeters. In such applications, update rates in the hundreds or thousands of Hertz aren’t uncommon, and the humble Nixie handled display refreshes with ease.
If you ever wanted to know about the physics of gas-discharge displays like the Nixie, the fifteen minutes starting at about 5:13 will give you everything you need. That basic problem boils down to the half-life of excited neon, or how long it takes for half the population of excited molecules to return to the ground state. That, in turn, dictates how long a given cathode will continue to visibly glow after it’s turned off, which determines how many digits will appear illuminated at once.
To answer that, they engaged a company in Prague with a camera capable of a mind-blowing 900,000 frames per second. Even though they found a significant afterglow period for each cathode, even at 100 kHz it’s clear which digit is the one that’s currently illuminated. They also looked at the startup of digits in a cold Nixie versus one that’s warmed up, leading to some fascinating footage at around 26:30.
We appreciate [Dalibor]’s attention to detail, not only in the craftsmanship of his custom tubes but in making sure they’re going to do their job. He recently did a failure analysis on some of his high-end clocks that showed the same care for his product and his brand.