The Art Of Nixies Hack Chat

Join us on Wednesday, October 28th at noon Pacific for The Art of Nixies Hack Chat with Dalibor Farný!

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”.

join-hack-chatOur Hack Chats are live community events in the Hack Chat group messaging. This week we’ll be sitting down on Wednesday, October 28 at 12:00 PM Pacific time. If time zones baffle you as much as us, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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State Of The Art For Nixies Gets A Boost From Dalibor Farny’s Supersize Prototype

Never one to pass up on a challenge, artisanal Nixie tube maker [Dalibor Farný] has been undertaking what he calls “Project H”, an enormous array of 121 Nixie tubes for an unnamed client. What’s so special about that? Did we mention that each Nixie is about the size of a sandwich plate?

Actually, we did, back in May when we first noted Project H in our weekly links roundup. At that time [Dalibor] had only just accepted the project, knowing that it would require inventing everything about these outsized Nixies from scratch. At 150 mm in diameter, these will be the largest Nixies ever made. The design of the tube is evocative of the old iconoscope tubes from early television history, or perhaps the CRT from an old oscilloscope.

Since May, [Dalibor] has done most of the design work and worked out the bugs in a lot of the internal components. But as the video below shows, he still has some way to go. Everything about his normal construction process had to be scaled up, so many steps, like the chemical treatment of the anode cup, are somewhat awkward. He also discovered that mounting holes in the cathodes were not the correct diameter, requiring some clench-worthy manual corrections. The work at the glassblower’s lathe was as nerve wracking as it was fascinating; every step of the build appears fraught with some kind of peril.

Sadly, this prototype failed to come together — a crack developed in the glass face of the tube. But ever the pro, [Dalibor] took it in stride and will learn from this attempt. Given that he’s reduced the art of the Nixie to practice, we’re confident these big tubes will come together eventually.

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This Tube Preamp Has A Nixie Volume Display

The pursuit of audiophile hi-fi is one upon which many superlatives and perhaps a little too much money are lavished. But it’s also a field in which the self-builder can produce their own equipment that is as good or often better than that which can be bought, so it provides plenty of interesting projects along the way. [Justin Scott]’s tube preamplifier is a great example, with its novel use of a pair of Nixie tubes to indicate the volume to which it has been set.

The audio side of the preamp comes courtesy of a four-tube kit from tubes 4 hi-fi, in which we notice another tube as power supply rectifier. The case is a beautifully made wooden affair with a professional front panel, but it’s the Nixies which make it a bit special. A high quality motorised potentiometer is used as a volume control, one of its multiple outputs is used as a simple potential divider to provide a voltage. This is read by an Arduino, which in turn drives the Nixies via a BCD-to-decimal decoder. The attention to detail in the whole project is at a very high level, and though he’s not shred any of its audio measurements with us, we’d expect it to sound as good as it looks.

If tube amplifiers interest you, we’ve delved into their design in the past, and it’s worth directing you to Justin’s matching amplifier, as well.

LED Matrix Takes You Down To Nixieland

It’s said that imitation is the sincerest form of flattery. Sure, there are some who might simply sugarcoat blatant plagiarism with fancy quotes, but there are still cases that come from well-intended, genuine admiration. The Nixie tube with its ember-like glow is a component that definitely gets a lot of such admiration, and being a fond LED enthusiast, [tuenhidiy] saw a perfect opportunity to imitate them with a RGB LED Matrix and build a virtual Nixie clock from it.

What may sound like just displaying images of Nixie tubes on a LED matrix, is actually exactly that. Using the UTFT library and converter, [tuenhidiy] turned pictures of individually lit-up Nixie tube digits into arrays of 16bit RGB values, and shows the current time on an ESP32-controlled 64×64 matrix with them. Providing two different image sizes, you can either place two tubes next to each other, or in a 3×2 arrangement, and of course have plenty of flexibility for future extensions. In the demo video after the break, you can see the two options in action while displaying both the full time, and only the seconds.

Unfortunately, it’s always difficult to judge an LED project through the lens of a camera, especially when looking for the characteristic color of a Nixie tube, but we take [tuenhidiy]’s word that it resembles it a lot better in reality. On the other hand, the pixelated look certainly adds its own charm, so you might as well go completely overboard with the colors — something we’ve seen with a different LED-themed Nixie alternative a little while back.

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Nixie Clock Turns Boombox

With all the Nixie Clock projects out there, it is truly difficult to come up with something new and unique. Nevertheless, [TheJBW] managed to do so with his Ultimate Nixie Internet Alarm Clock (UNIAC) which definitely does not skimp on cool features.

Although the device does tell time, it is actually a portable boombox that streams music from Spotify using a Raspberry Pi Zero running Mopidy. The housing made from smoked acrylic, together with the IN-12A Nixie Tubes, an IN-13 VU meter, and illuminated pushbuttons give this boombox kind of a 70s/90s mashup retro look. The acrylic housing is special since it consists of only two plates which were bent into shape, resulting in smooth edges in contrast to the often used finger or T-slot design.

For his project [TheJBW] designed a general-purpose Nixie display that can not only show time and date but also the elapsed or remaining track time. He also came up with a Python generated artificial voice that reads you the current playlist. The only problem [TheJBW] has run into was when trying to design a suitable battery system for the device, as the high current draw during start-up can easily cause brownouts. Due to time constraints, he ended up with a MacGyver-style solution by taping a 12 V battery pack from Amazon to the back of the unit.

Among the large variety of Nixie projects we don’t think we have ever seen them in an audio player before except for some attempts of using them as an amplifier. However, it is known that IN-13 tubes make a great VU meter.

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BCD To I2C: Turning A Nixie Counter Into Whatever You Want It To Be

Whenever a project calls for displaying numbers, a 7-segment display is the classic and straightforward choice. However, if you’re more into a rustic, retro, almost mystical, and steampunky look and feel, it’s hard to beat the warm, orange glow of a Nixie tube. Once doomed as obsolete technology of yesteryear, they have since reclaimed their significance in the hobbyist space, and have become such a frequent and deliberate design choice, that it’s easy to forget that older devices actually used them out of necessity for lack of alternatives. Exhibit A: the impulse counter [soldeerridder] found in the attic that he turned into a general-purpose, I2C controlled display.

Instead of just salvaging the Nixie tubes, [soldeerridder] kept and re-used the original device, with the goal to embed an Intel Edison module and connect it via I2C. Naturally, as the counter is a standalone device containing mainly just a handful of SN74141 drivers and SN7490 BCD counters, there was no I2C connectivity available out of the box. At the same time, the Edison would anyway replace the 7490s functionality, so the solution is simple yet genius: remove the BCD counter ICs and design a custom PCB containing a PCF8574 GPIO expander as drop-in replacement for them, hence allowing to send arbitrary values to the driver ICs via I2C, while keeping everything else in its original shape.

Containing six Nixie tubes, the obvious choice is of course to use it as a clock, but [soldeerridder] wanted more than that. Okay, it does display the time, along with the date, but also some sensor values and even the likes on his project blog. If you want to experiment with Nixie tubes yourself, but lack a matching device, Arduino has you obviously covered. Although, you might as well go the other direction then.

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