“Nixie” Tubes Sound Good

A tube is a tube is a tube. If one side emits electrons, another collects them, and a further terminal can block them, you just know that someone’s going to use it as an amplifier. And so when [Asa] had a bunch of odd Russian Numitron tubes on hand, an amplifier was pretty much a foregone conclusion.

A Numitron is a “low-voltage Nixie”, or more correctly a single-digit VFD in a Nixiesque form factor. So you could quibble that there’s nothing new here. But if you dig into the PDF writeup, you’ll find that the tubes have been very nicely characterised, situating this project halfway between dirty hack and quality lab work.

It’s been a while since we’ve run a VFD-based amplifier project, but it’s by no means the first time. Indeed, we seem to run one every couple years. For instance, here is a writeup from 2010, and the next in 2013. Extrapolating forward, you’re going to have to wait until 2019 before you see this topic again.

Hot Russian Tubes

On the heels of our post on retro-Soviet transistor teardowns and die-shots, [nikitas] wrote in to tell us about a huge thread on rare vacuum devices of all varieties: oddball cathode-ray tubes, obscure Nixies, and strange Soviet valves. We thought the other forum post was overwhelming at just over 110 pages, but how about 391 pages (and counting) of blown-glass electronics?

If you read through the decaptholon, we mentioned that a particularly enthusiastic poster, [lalka], looked to be cataloguing every Soviet oscillator circuit. It turns out that he’s also the one behind this incredible (random) compendium of everything that’s had the air sucked out of it.

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45-Year Old Nixie Calculator Turned UDP Server

In this beautiful and well-documented reverse engineering feat of strength, [Eric Cohen] reverse-engineered a 1971 Singer calculator to gain control of the fabulous Nixie tubes inside. Where a lesser hacker would have simply pulled the tubes out and put them in a more modern housing, [Eric] kept it all intact.

Not even content to gut the box and toss some modern brains inside, he snooped out the calculator’s internal wiring, interfaced a Raspberry Pi to it, and overrode the calculator’s (860 Hz) bus system. With the Pi on the inside, controlling the Nixie tubes, he did what any of us would do: set up a UDP server and write an Android app for his phone to push ASCII data over to the former calculator. When it’s not running in its default clock mode, naturally.

nixie-internals

All of this is extraordinarily well documented both on his website, in a slide presentation (PDF), and in video (embedded below). Our hats are tipped to the amazing attention to detail and fantastic documentation.

Now where is that Singer EC1117 calculator from 1971 that we’ve been saving for just such an occasion?

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Hackaday Prize Entry: A Programmable Calculator With Nixie Tubes

For [Robert]’s entry into The Hackaday Prize, he’s starting off with some basic questions. What’s better than a Nixie tube? More Nixies. What’s better than a calculator? An RPN calculator. What do you get when you combine the two? A calculator that is absurdly large, even by 1970s desk calculator standards, uses a lot of power, and takes up too much space. Sounds good to us.

Nixies, at least when there are a lot of them, are tricky devices. They only draw about 50mA of current, but they only light up when above 150V. That’s only about seven watts, and it’s easy enough for the Arduino-heads out there to build a circuit to drive a few Nixies for a clock. Driving dozens of Nixies is a bit harder. For [Robert]’s RPN calculator, he’s estimating a little under 50W of power being dumped into this calculator.

With the considerable power considerations taken care of, [Robert] turned his attention to the display board. This is going to be a very impressive build, with 80 IN-12B tubes organized in four stack levels of twenty tubes each. The tubes will be controlled with the Maxim MAX6922 VFD driver. This chip has a serial interface, which means it’s relatively easy to have any microcontroller blink these tubes. And of course, it does double-duty as a clock.

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Nixie Timer Is Easy To Read Across The Kitchen

Nixie clocks. Nixie power meters. Nixie thermometers, speedometers, and even Nixies for personal adornment. Is there anything that hasn’t been Nixie-fied? How about a Nixie kitchen timer? Beyond the Nixie tube, this is a great build. Check out the video below the break.

As so often happens with Nixie aficionados, [Kouichi Kuroi] started with tubes and searched for a project to use them on. A wonky kitchen timer provided the thinly veiled excuse for the build – after all, anyone can drop a couple of yen on a commercial replacement, right? The timer features four IN-12 tubes and a large numeric keypad up front on a laser-cut acrylic case. For those who quibble with the keypad’s aesthetics and the wisdom of a Nixie project in the kitchen environment, [Ko] points out that an IP65 keypad would have more than doubled the price of the build, and a little common sense goes a long way to keeping the high-voltage side from meeting anything wet. In addition to countdown capability, the timer can also act as a stopwatch and display the time of day, and the Nixie tubes provide great visibility compared to seven-segment LCD timers.

As for the aforementioned Nixie projects, here’s a clock, power meter, thermometer, speedometer and necklace that we’ve featured before. What’s next for Nixies? We don’t know, but we’re keen to see what you come up with.

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Powering A Lot Of Nixie Tubes

[Limpkin] has an idea for a project that uses a lot of IN-9 Nixie tubes. Where a Nixie tube clock would only use four or six tubes, [Limpkin] is looking at fifty IN-9 bar graph Nixie tubes. These tubes only light up above 100 Volts and draw about half an amp. That’s 64 Watts, according to the math on the project page, so how does [Limpkin] plan on powering these tubes? With a big high voltage power supply.

The power supply [Limpkin] designed is more or less what you would expect to find in any power supply. There’s a transformer, a bunch of caps, and a rectifier. Going with a standard laminated core transformer would mean this power supply would be huge and heavy, but once again eBay comes to the rescue with a small, 150 Watt toroidal transformer. The largest output on the transformer was two 24 V outputs. Combining those outputs gets [Limpkin] to 48V AC, or 68V peak to peak. A full wave voltage doubler with two caps and two diodes gives [Limpkin] the 136V DC that will power the tubes.

Combine the high voltage circuit with a 9V AC tap, a small bridge rectifier, and a few more caps, and [Limpkin] had a supply that would power the tubes and the rest of the electronics in his multiple Nixie tube project. A few passes with a CNC mill gave the power supply a nice case topped off with a foreboding toroidal transformer ready to power a beautiful neon project.

Nixie Thermometer Destined For Custom PC Case

There’s no denying the retro appeal of the warm glow of a set of Nixies, and when a friend was looking for a unique touch for the case of his new liquid-cooled PC, [Luca] pitched in with this sweet Nixie thermometer.

From the look of [Luca]’s detailed blog entries, he’s been at this build since the New Year. He starts with a list of requirements, including the oddly specific need for a round PC board. For the thermometer, three Nixies are enlisted for the display, two for the temperature and one for the units. Everything was prototyped on perf board before committing to a PCB design, but even with careful planning, the Nixie sockets on the final PCB came out a tiny bit too close together. Luckily the tubes still fit, even if they are snuggled together some. And yes, the tube bases all include the hated RGB LEDs – hey, it’s what the customer wanted. The specs are for the colors to change at the touch of a button; we’d like to see a color gradient linked to the temperature – blue for “nice and cool”, red for “leave the room.” You can see the finished thermometer in action below the break.

The recent run of Nixie projects continues unabated, and this one has a nice look that’s sure to complement the finished case. We’ve asked [Luca] to keep us up-to-date on the project, so hopefully we’ll get a look at why a round PCB is needed. While we wait for that, check out an earlier Nixie thermometer build with a bar graph twist.

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