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.
In the days before every piece of equipment was an internet-connected box with an OLED display, engineers had to be a bit more creative with how they chose to communicate information to the user. Indicator lights, analog meters, and even Nixie tubes are just a few of the many methods employed, and are still in use today. There are, however, some more obscure (and arguably way cooler) indicators that have been lost to time.
[Aart Schipper] unearthed one such device while rummaging around in his father’s shed: a pair of Burroughs Bar Graph Glow-Transfer Displays. These marvelous glowing rectangles each have two bars (think the left and right signals on an audio meter, which is incidentally what they were often used for), each with 201 neon segments. Why 201, you may ask? The first segment on each bar is always illuminated, acting as a “pilot light” of sorts. This leaves 200 controllable segments per channel. Each segment is used to “ignite” its neighboring segment, something the manufacturer refers to as the “Glow-Transfer Principle.” By clever use of a three-phase clock and some comparators, each bar is controlled by one analog signal, keeping the wire count reasonably low.
Sometimes you find something that looks really cool but doesn’t work, but that’s an opportunity to give it a new life. That was the case when [Davis DeWitt] got his hands on a weird Soviet-era box with four original Nixie tubes inside. He tears the unit down, shows off the engineering that went into it and explains what it took to give the unit a new life as a clock.
A lot can happen over decades of neglect. That was clear when [Davis] discovered every single bolt had seized in place and had to be carefully drilled out. But Nixie tubes don’t really go bad, so he was hopeful that the process would pay off.
The unit is a modular display of some kind, clearly meant to plug into a larger assembly. Inside the unit, each digit is housed in its own modular plug with a single Nixie tube at the front, a small neon bulb for a decimal point, and a bunch of internal electronics. Bringing up the rear is a card edge connector.
[IMSAI Guy] bought a fake Nixie clock, and luckily for all of us has filmed a very close look and demonstration. Using OLED displays as the fake Nixie elements might seem like cheating to some, the effect is really very well done.
When it comes to Nixie elements, it’s hard to say which gets more attention and project time from hardware folks: original Nixie tube technology, or fake Nixie elements. Either way, their appeal is certainly undeniable.
Authentic Nixie elements require high voltages and are labor-intensive to manufacture to say the least, and as far as fake Nixie elements go, this one looks pretty good once it lights up. You can see it in action in the video, embedded below.
We feature a lot of clocks here at Hackaday, but alarm clocks seem to be less popular for some reason. Maybe that’s because no-one enjoys being woken up in the morning, or simply because everyone uses their smartphone for that purpose already. In any case, we’re delighted to bring you [Manuel Tosone]’s beautiful Nixie tube alarm clock that cleverly combines modern and classic technologies in a single package.
The clock and alarm functionalities are implemented by a PIC24 microcontroller on a custom mainboard. It keeps track of time through its real-time clock with battery backup, and plays a song from an SD card when it’s time to wake up. A 2 x 3 W class D audio amplifier plus a pair of stereo speakers should be able to wake even the heaviest sleepers.
Of course, the real party piece is the clock’s display: four IN-4 Nixie tubes show the time, with neon tubes indicating the day of the week. The 180 V needed for the Nixies is generated by an MC34063A-based boost converter, which also powers the neon tubes.
Instead of using the standard current-limiting resistor for each Nixie tube, [Manuel] designed an array of transistor-based current sources: this enables linear control of the tubes’ brightness, and should keep the amount of light constant even as the tubes age. The individual segments are switched by SN75468 Darlington arrays, with no need for those hard-to-find SN74141 drivers.
The mainboard and the display are housed inside a 3D-printed case that mimics the style of 1980s digital alarm clocks, but with a nice 1970s twist courtesy of those Nixie tubes. [Manuel]’s GitHub page has all the schematics as well as extensive documentation describing the circuit’s operation — an excellent resource if you’re planning to build a Nixie project yourself. If Nixies aren’t your thing, you can also make an alarm clock with a VFD tube, or even roll your own luminous analog dial.
Rǒta counts things. That’s it, really — what a cheap little mechanical counter does with a thumb press, or what you can do by counting on your fingers and toes, that’s pretty much all that Rǒta does. But it does it with style.
OK, that’s being a bit unfair to [Kevin Santo Cappuccio] — Rǒta has a few more tricks up its sleeve than simple counting. But really, those functions are just icing on the cake of how this little gadget looks. Rǒta was built around the unbeatable combination of a rotary telephone dial mechanism and a trio of Nixie tubes. The dial looks like it might have come from an old pay phone, all shiny and chrome and super robust looking. The Nixies sit atop the dial on a custom PCB, and everything, including the high-voltage supply for the tubes, is enclosed in a 3D printed case with a little bit of a Fallout vibe.
But what does this thing do? Actually, quite a lot. It’ll count up and down, using whatever number you dial into it. You can either increment from zero, or enter any three-digit number as the starting count. It keeps track of the score of your golf game, if that’s your thing, and it’s also got a stopwatch function. You can even dial up a display of the current battery voltage. It takes some ingenuity to use just the dial for all these functions, but that’s as easy as dialing the operator used to be — dialing 0 puts it in menu mode, allowing you to access any of the functions printed on the card in the center of the dial. It’s pretty clever — check out the video below.
Is it particularly useful? Perhaps not. But when has that ever been a measure of the worth of a project? Something like this rotary cellphone might be more useful, but sometimes looking great is good enough.
A spectrum visualizer is always a fun project, but we really liked [Yannick99]’s take on it since it uses seven IN-13 Nixie tubes for the display. The tubes, of course, need high voltage so part of the project is a high voltage power supply. The spectrum part is a little more ordinary using an op amp and an MSGEQ7 filter IC.
The chip feeds a microcontroller and the microcontroller, with a little help, drives the tubes. The results are great, as you can see in the video below. There are several other videos showing the testing and prototyping, too. The MSGEQ7 is a cute chip that offloads the usual FFT logic from the microcontroller. It does all the work and communicates in a very unusual way. You reset the device and then pulse the strobe input. This causes an analog voltage to appear on the output pin corresponding to the 63 Hz band level. Another strobe pulse selects the next band and you just repeat indefinitely, something the microcontroller is good at.
The only issue, of course, is locating IN-13 tubes. They are around if you look for them, but they may not be cheap. Expect to pay about $20 each for them, more or less. We wondered if you could make an LED look-alike replacement. If you are wondering about the lifespan of these tubes, someone’s already done the testing.