Random Number Generator Is A Blast From The Past

Hackers love random numbers, or more accurately, the pursuit of them. It turns out that computers are so good at following our exacting instructions that they are largely incapable of doing anything that would fit the strict definition of randomness — which has lead to some elaborate methods of generating the unexpected.

Admittedly, the SB42 Random Number Generator built by [Simon Boak] isn’t exactly something you’d be using for cryptography. The method used to generate the digits, a pair of 555 timers sending pulses through linear-feedback shift registers, would at best be considered pseudo-random. Plus the only way of getting the digits out of the machine is by extracting them from the Nixie tubes with your Mark I Eyeballs. But it absolutely excels at the secondary reason many hackers like to build their own randomness rigs — it looks awesome.

Externally, it absolutely nails the look of a piece of vintage DIY year. Down to the classic white-on-black label tape. But open up the hood, and you’re treated to a real rarity these days: wirewrap construction. In an era where you can get PCBs made and shipped to your door for literally pennies, [Simon] is out there keeping the old ways alive. It doesn’t just look the part either. Unlike most modern projects we see, there isn’t a multi-core microcontroller behind the scenes doing all the work, it’s logic gates all the way down.

This isn’t the first random-ish number generator that we’ve seen use shift registers. But if you’re looking for something that might actually pass some randomness checks, and don’t mind working with something a bit spicy, you could check out some of the previous devices we’ve covered that used radioactive decay as an entropy source.

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Four large nixie tubes showing the number 2

[Dalibor Farný]’s Enormous Nixies Light Up Contemporary Art Museum

Nixie tubes come in many shapes and sizes, but in only one color: the warm orange glow that makes them so desirable. They don’t usually come in large numbers, either: a typical clock has four or six; a frequency counter perhaps eight or nine. But some projects go bigger – a lot bigger in [Dalibor Farný]’s case. He built an art installation featuring more than a hundred jumbo-sized nixie tubes that make an entire wall glow orange.

This project is the brainchild of renowned installation artist [Alfredo Jaar], who was invited to create an exhibition at the Hiroshima Museum of Contemporary Art. Its title, Umashimenkana, means “we shall bring forth new life” and refers to a poem describing the birth of a child amid the suffering and despair following the atomic bombing of Hiroshima. Visitors to the exhibit experience a dark room where they see a wall of orange numbers count down to zero and erupt into a waterfall of falling zeroes.

Nixie tube expert [Dalibor] was the go-to person to implement such an installation – after all, he’s one of very few people making his own tubes. But even he had to invest a lot of time and effort into scaling them up to the required 150 mm diameter, with 135 mm tall characters. We covered his efforts towards what was then known as the H-tube project two years ago, and we’re happy to report that all of the problems that plagued his efforts at the time have since been solved.

The cathodes of a large nixie tube being assembledOne of the major issues was keeping the front of the tubes intact during manufacture. Often, [Dalibor] and his colleagues would finish sealing up a tube, only for the front to pop out due to stress build-up in the glass. A thorough heating of the entire surface followed by a slow cooling down turned out to be the trick to evening out the stress. All this heat then caused oxidation of the cathodes, necessitating a continuous flow of inert gas into the tube during manufacture. Those cathodes already had to be made stronger than usual to stop them from flexing, and the backplate light enough to keep everything shock resistant. The list goes on.

After ironing out these quirks, as well as countless others, [Dalibor] was finally able to set up a small-scale production line in a new workshop to get the required 121 tubes, plus spares, ready for shipment to Japan. The team then assembled the project on-site, together with museum staff and the artist himself. The end result looks stunning, as you can see in the excellent video embedded below. We imagine it looks even better in real life – if you want to experience that, you have until October 15th.

You might remember [Dalibor] from his excellent video on nixie clock fault analysis – which we hope won’t be necessary for Umashimenkana. He might be able to make your favorite shape into a nixie tube, too. Thanks for the tip, [Jaac]!

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Conductive Gel Has Potential

There are some technologies first imagined in the Star Trek universe have already come to exist in the modern day. Communicators, tablet computers, and computer voice recognition are nearly as good as seen in the future, and other things like replicators and universal translators are well on their way. Star Trek: Voyager introduced a somewhat ignored piece of futuristic technology, the bio-neural gel pack. Supposedly, the use of an organic gel improved the computer processing power on the starship. This wasn’t explored too much on the series, but [Tom] is nonetheless taking the first steps to recreating this futuristic technology by building circuitry using conductive gel.

[Tom]’s circuitry relies on the fact that salts in a solution can conduct electricity, so in theory filling a pipe or tube with a saline solution should function similarly to a wire. He’s also using xanthan gum to increase viscosity. While the gel mixture doesn’t have quite the conductivity of copper, with a slight increase in the supplied voltage to the circuit it’s easily able to be used to light LEDs. Unlike copper, however, these conductive gel-filled tubes have some unique properties. For example, filling a portion of the tube with conductive gel and the rest with non-conductive mineral oil and pushing and pulling the mixture through the tube allows the gel to move around and engage various parts of a circuit in a way that a simple copper wire wouldn’t be able to do.

In this build specifically, [Tom] is using a long tube with a number of leads inserted into it, each of which correspond to a number on a nixie tube. By moving the conductive gel, surrounded by mineral oil, back and forth through the tube at precise intervals each of the numbers on the nixie tube can be selected for. It’s not yet quite as good as the computer imagined in Voyager but it’s an interesting concept nonetheless, not unlike this working replica of a communicator badge.

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Nixie Display Module Is Addressable Via SPI

There are plenty of SPI interface screens on the market, but few of them have the charm of the good old Nixie tube. [Tony] decided to whip up a simple three-Nixie module that could be addressed via SPI. 

The stacked construction keeps things compact.

The module relies on a PIC16F15344 microcontroller to run the show, using its built-in SPI interface. It’s built with four stacked-up PCBs for ease of assembly and testing. It uses an internal buck converter to create the 170 volts required for the Nixie tubes from a 6 to 12 volt input. The high-voltage lines are routed towards the inside of the stack to minimize any nasty shocks when handling, though caution would still be advisable.

Driving the display is as simple as sending 16-bit words over the SPI interface, with the device operating in SPI client mode 1. If you’re looking for a simple way to have projects write output to a nice Nixie display, this module could be just what you’re looking for. Alternatively, if you can’t lay your hands on the tubes, there are other pretty solutions out there, too. Video after the break.

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2022 Sci-Fi Contest: Nixie Calculator Is Resplendent In Walnut Enclosure

The Nixie tube is one of the most popular display technologies amongst the hacker and maker set. Glowing numerals can warm even the coldest heart, particularly when they’re energized with hundreds of volts. [ohad.harel] used these glorious displays to build the TORI Nixie Calculator, with beautiful results. 

The build uses seven IN-12 Nixie tubes for numerals, along with an IN-15A which displays mathematical symbols like +, %, and M. It’s equipped with a 32-key keyboard using mechanical key switches. Everything is wrapped up in a beautiful walnut enclosure that fits the tubes and keyboard perfectly, giving the final build a nice mid-century aesthetic.

Impressively, it goes beyond the basic usual calculator functions, also handling conversions between metric and imperial units. It’s a nice feature that would make it a wonderful tool to have on one’s desk beyond the simple aesthetic charm of the Nixie tubes.

Nixie projects never seem to die. Their beauty and warmth captivates builders to this day. Indeed, we’ve even seen some makers go to the trouble of creating new tubes from scratch!

A six digit Nixie clock on a desktop

Upcycled Nixie Clock Fit For A Friend

Building a clock from parts is a rite of passage for makers, and often represents a sensible introduction into the world of electronics. It’s also hard to beat the warm glow of Nixie tubes in a desktop clock, as [Joshua Coleman] discovered when building a Nixie tube clock for a friend.

The original decision to upcycle the chassis from an unrepairable Heathkit function generator came a little undone after some misaligned cutting, so the front panel ended up being redesigned and 3D printed. This ended up being serendipitous, as the redesigned front panel allowed the Nixie tubes to be inset within the metal chassis. This effect looks great, and it also better protects the tubes from impact damage.

Sourcing clones of the 74141 Nixie driver ICs ended up being easier than anticipated, and the rest of the electronics came together quickly. The decoders are driven by an Arduino, and the IN-4 Nixie tubes are powered by a bespoke 170 volt DC power supply.

Unfortunately four of the tubes were damaged during installation, however replacements were readily available online. The gorgeous IN-4 Nixie tube has a reputation for breaking easily, but is priced accordingly on auction sites and relatively easy to source.

The build video after the break should get any aspiring Nixie clock makers started, but the video description is also full of extra information and links for those needing help getting started.

We’re not short on clock hacks here at Hackaday, so why not check out a couple more? This retro-inspired LED clock looks like its right out of a parallel universe, or maybe this stunning Nixie clock driven by relays will strike your fancy.

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Closeup of the car dash with nixie tubes

Retro Future Nixie Corvair Instrument Panel

The future we know today looks very different than the one envisioned in the 60s and 70s. For starters, it has far too few Nixie tubes. An oversight [nixiebunny] wants to address with his Nixie tube instrument panel.

All the essential info is there: engine temperature, tachometer, speed, battery voltage, and even odometer. You might have noticed that there isn’t a clock. The justification that [nixiebunny] gives is that he’s always wearing his Nixie watch, so a clock in his car seems redundant. There is also a gap in the panel to allow an oil pressure display. Corvairs are known for throwing belts next to the oil sender, so any attached sensor needs to be designed well and thought through. A Teensy receives engine telemetry data (no OBDII port to hook into — GM didn’t come out with the first OBD port until the 80s) from the engine bay. The data is transformed into SPI data sent to the 74HC595 shift register chain via a CAT5 cable. Details are a little sparse, but we can see a custom PCB to fit the shape of the hole in the dash with the different Nixie tube footprints silkscreened on.

We love seeing Nixie tubes in unexpected places. Like this POV Nixie clock or this Nixie robot sculpture.