I've always loved the look of vintage display hardware. Everybody knows the unique look and glow of nixie tubes, and they have such a following with hackers and makers for a good reason. The issue is, I'm still new to electronics, and I feel like I don't have the knowledge or experience to handle the high voltages that some of them require to work!
There's other alternatives, sure, like the much easier to drive and use minitrons. For the most, they used small pieces of incandescent filament in a small glass and metal package. A few of them could even run at a very easy to drive 5v. Unfortunately, they're hard to find, and are starting to fail because of age and the fact that they need to be inside a perfect vacuum inside a small package.
I want to make a modern version of a minitron that runs with easy to source parts, operates at an easy to use voltage, and can be made using accessible tools like a 3d printer and laser cutters.
It's amazing what you can find on Aliexpress. After some searching and keyword manipulation, I was able to find a source for led filaments at a reasonable price. I chose the 12v 38mm version for their ease to drive compared to the other voltages and how readily you can find 12v power supplies too. The filaments I chose also come in a surprising variety of colours. There's red, green, blue, cool white and warm white. I chose red because it's a nice mix of the minitron look and a modern seven segment. I may purchase some green LEDs in the future to see if I can make a VFD aesthetic 16 segment, but that's for another project!
When the filaments arrived, I could make my PCBs, which went amazingly quick because of the simplicity. All I needed to do was make a footprint for my LEDs and methodically go back to the renders and CAD I did to place everything correctly. Since I like to add details to my silk screen too, I added an imaginary product number using the amazing Garoa Hacker Clube Bold and a logo using Densmore, as well as curved traces that'd look beautiful with something like OSH Parks after dark service.
After a quick turn around of only a week, I had my boards in hand. Assembly for four digits went quickly, but I also had to be careful while I was doing so. The leds for the filaments are placed on a ceramic backer and coated in silicone, making them incredibly delicate. I'd strongly recommend using a PCB vice or even just a soft piece of upholstery foam when soldering on the back side
Using a driver board based on another person's design, I was able to test my PCBs and see how things looked. The aesthetic with out a case is amazing, but because of their fragility, it's best that I make a case for them. It'd help with visibility and contrast for the digits too, since I don't always live in dramatic two tone lighting!
Everybody loves nixies, they have a retro-futuristic look to them despite being used more than 60 years ago, and the soft warm glow and 3d view they have as they shift from digit to digit is uniquely theirs. Nixies are absolutely a dated technology though, and come with all the struggles of old hardware sometimes; they can be hard to power with high voltages, they're sometimes delicate, and most importantly, they're hard to source too.
I wanted to build a clock using them for the longest time, but I'm still just a beginner, so using 170v is very daunting to me until I learn more proper PCB routing and how to protect and isolate the lower voltage components that control them.
There does exist an alternative, and it's almost a cousin to the nixie tube, the numitron and minitron. Numitrons more closely resemble a nixie, but use a seven segment digit to display numbers instead of several plates. While they still need a lot of voltage, minitrons can actually run at a much more reasonable 5v and in a smaller square package. Still, they have some of the issues older hardware always does. They're hard to find, and with age the small package tends to lose that crucial vacuum that it needs to run.
Thankfully, in the modern age, there exists some alternatives and recreations of incandescent filament. A lot of us have likely seen it too in those en vouge Edison bulbs. They're made of led dies put directly on to a ceramic backer, then covered in silicone. Depending on how the LEDs are configured in parallel and/or series, they can easily be run with 3v, 12v or even 24v.
That brings me to my idea, what if I used led filaments to recreate the look of a numitron as close as I could? They'd be a lot more durable and safer to drive considering the voltages you can drive them at. With a quick draft in CAD, it honestly looks promising!