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.
Tiny PCBAs and glowy VFD tubes are like catnip to a Hackaday writer, so when we saw [hamster]’s TubeCube tube segment driver we had to dig in to learn more. We won’t bury the lede here; let’s enjoy a video of glowing tubes before we go further:
The TubeCube is built to fit the MiniBadge badge addon standard, which is primarily used to host modules on the SAINTCON conference badge. A single TubeCube hosts a VFD tube, hardware to provide a 70 V supply, and a microcontroller for communication and control. Each TubeCube is designed to accept ASCII characters via UART to display on it’s display, but they can also be chained together for even more excitement. We’re not sure how [hamster] would be able to physically wear the beast in the video above, but if he can find a way, they all work together. If you’re interested in seeing the dead simple UART communication scheme take a look at this file.
We think it’s also worth pointing about the high voltage supply. To the software or mechanically minded among us it’s easy to get trapped thinking about switching power supplies as a magical construct which can only be built using all-in-one control ICs. But [hamster]’s supply is a great reminder that a switching supply, even a high voltage one, isn’t as complex as all that. His design (which he says was cribbed from Adafruit’s lovely Ice Tube Clock) is essentially composed of the standard primitives. A big low voltage capacitor C1 to source the burst of energy which will be boosted, the necessary inductor/high voltage cap C2 which ends up at the target voltage, and a smoothing cap C3 to make the output a little nicer. It’s controlled by the microcontroller toggling Q1 to control the current flow through L1. The side effect is that by controlling the PWM frequency [hamster] can vary the brightness of the tubes.
Right now it looks like the repository has a schematic and sources, which should be enough to build a small tube driver of your own. If you can’t get enough TubeCubes, there’s one more video (of a single module) after the break.
Us: “I’ll take Retro style displays we absolutely have to have for $200, Alex.”
Trebek: “This nixie tube is unlike any conventional tube you’ve seen before, handbuilt and NOT numbers or letters.”
Us: “What is FriendlyWire’s new logo tube?”
Trebek: “Heck yeah.”
Nixie tubes are the vacuum technology that manages to do far less than a graphic LCD while looking about a million times cooler. Generally speaking, these tubes are no longer manufactured, and the old stock you can get your hands on usually contain a set of filaments shaped like numbers. But @FriendlyWire’s tweet of this Nixie tube by [Dalibor Farny] breaks both of those rules. This handmade tube isn’t just a numerical display or a colon display (the punctuation mark, get your head out of the gutter). It’s a custom logo, and it’s beautiful.
Packing twin Nixie tubes, the watch displays hours first, then minutes. An accelerometer is fitted, switching the tubes on when the user checks the watch. There’s also Bluetooth and WiFi connectivity, which can be used to set the time as well as check the remaining battery life. Standby time is estimated to be 350 hours, thanks to a low-power microcontroller and keeping the tubes off most of the time.
The presentation is where this watch really shines, sporting as it does an RGB LED for backlighting and an attractive aluminium case. The design is simple, helping to highlight the industrial beauty of the Nixie tubes themselves. The housing was first mocked up with 3D printed parts, before the final piece was CNC milled. [RemcoK3] is contemplating anodizing the watch, but we think that the brushed aluminium already looks perfect.
We love our clocks around here and we love nixie tubes as well. The combination of the two almost seems to be a no-brainer. With the modern twist of an ESP8266, Reddit user [vladco] built a minimalist nixie tube clock.
The build starts with the nixie tubes, Russian In4s, each one mounted on its own small circuit board. Each board is chained together and they’re mounted on a wooden frame. The frame is mounted inside a nice wooden case which was designed in Fusion 360 and milled out of oak at a local hackerspace.
There are no controls on the case. No buttons or knobs. This clock is set via the EPS8266 which gets the time and updates the shift registers that set the numbers on each of the tubes. The clock dims at night so it’s not as bright. [vladco] wrote a web UI to set the time and interact with the tubes.
The code and files for the case and circuit board are available online. The result is a nice, minimalist clock for your desk. There are plenty of clock builds on the site, several built from nixie tubes, including another nixie tube clock with an ESP8266, and another.
The shield uses HV5812 drivers to handle the high-voltage side of things, a part more typically used to drive vacuum fluorescent displays. There’s also a DHT22 for temperature and humidity measurements, and a DS3231 real time clock. It’s designed to work with IN-12 and IN-15 tubes, with the part selection depending on whether you’re going for a clock build or a combined thermometer/hygrometer. There’s also an enclosure option available, consisting of two-tone laser etched parts that snap together to give a rather sleek finished look.
Nixie clocks, they’re a bit of a cliché, aren’t they? But still, they’re pretty to look at.
[Marcin Saj] has completely got our number, and with his Useless Nixie Device has stripped away any pretence of functionality from his Nixie and concentrated solely on the looking pretty part. It’s a box that steps through the display on any Nixie tube through the use of a set of pluggable socket modules, and it’s encased in an extremely attractive lase-cut acrylic enclosure. Internally it’s an extremely simple device, with a trusty 555 oscillator clocking a 4518 counter that in turn feeds 74141 driver. There is a MAX1771 boost converter in there too to create some high voltage for the tubes.
So it’s a pretty device and you can plug almost any Nixie into it given the right adapter. We guess it might be useful if you have a warehouse full of Nixies to test, but beyond that it’s a pretty desk toy. Still, it’s nice to see a Nixie project that’s not just another clock.