I came across this while looking at all kinds of clocks and the origins of operational amplifiers. I've used these but never realized that you could use the hysteresis to make counters.

I originally found this link:

https://www.pa3fwm.nl/projects/sdr/

About a completely home-grown software defined radio that is on the web as well at http://websdr.ewi.utwente.nl:8901/ , you can use it to listen to all kinds of interesting signals, for instance an atomic clock, DCF77 at 77.5 KHz CW.

That project is absolutely mind-blowingly complex and the fact that it works at all has me amazed.

I believe this is operating a similar or same architecture as this historically significant quartz clock time standard:

https://www.rmg.co.uk/collections/objects/rmgc-object-79394

Believe it or not this piece was rescued from being scrapped by my father, who had unique interest in both horology and was a professional electronics engineer. This clock was expertly restored on our family dining table at home - including the build of a new solid state power supply for it. I think the museum still powers up this clock for display, and you can watch the large neon decade dividers doing their thing.

EDIT: appears to have been removed from display according to the linked archive page.

None bulbs are kind of fascinating— in part due to their ability to act as relaxation oscillators [1]. I found an old electronics hobbyist magazine going into details [2] (Man, I love the linked site, BTW, so many awesome old electronic projects to pore over.)

[1] https://en.wikipedia.org/wiki/Relaxation_oscillator

[2] (Starts page 21—as printed in the corners of the pages) https://www.worldradiohistory.com/Archive-Elementary-Electro...

Nixie-clock using neon lamps as logic elements (2007) - https://news.ycombinator.com/item?id=27956488 - July 2021 (2 comments)

Nixie-clock using neon lamps as logic elements (2007) - https://news.ycombinator.com/item?id=16549144 - March 2018 (16 comments)

I assume nixie tubes were introduced to a new generation of nerds via their appearance in Portal 2, at one of the lowest (=oldest) layers of Aperture Science. What a cool ancestor to the comparatively boring post-1970s 7 segment display!

Includes link to a 2020 one that's still operational by the same person in the addendum at the bottom!