The Neon glow of a Nixie tube makes for an attractive clock, but that’s not enough neon for some people. [Changliang Li] is apparently one of those people, because he’s using soviet-era cold-cathode tubes as the logic for his “Soviet-Era Style Clock”
Aside from the nixies for display, the key component you see working in this beautiful machine are the MTX-90 cold cathode thyratrons, which look rather like neon tubes in action. That’s because they essentially are, just with an extra trigger electrode (that this circuit doesn’t use). The neon tubes are combined into a loop counter, which translates the 50 Hz mains circuit in to seconds, minutes, and hours. The circuit is not original to this project, and indeed was once common to electronics books. The version used in this project is credited to [PA3FWM].
The Nixie tubes are new-made by [Sadudu] of iNixie labs, and we get a fascinating look in how they are made. (Tubemaking starts at around 1:37 in the video below.) It looks like a fiber laser is used to cut out glow elements for the tube, which is then encapsulated on a device which appears to be based around a lathe.
The cold-cathode tubes used as logic rely on ambient light or background radiation to start reliably, since the trigger electrode is left floating. In order to ensure reliable switching from the thyratrons, [Changliang Li] includes a surplus smoke detector source to ensure sufficient ionization. (The video seems to imply the MTX-90 was seeded with radioisotopes that have since decayed, but we could find no evidence for this claim. Comment if you know more.)
The end result is attractive and rather hypnotic. (Jump to 3:37 to see the clock in action.) If you want to know more about this sort of use for neon lamps (and the Soviet MTX-90) we featured a deeper dive a while back.
Thanks to [Changliang Li] for the incandescent tip. If one of your bright ideas has had a glow up into a project, don’t hesitate to share it on our tips line.
The individual numerals are not cut on a fiber laser. They are chemically etched. It’s just the backing plate that is laser engraved. Also that smoke detector source is not Radium-241 as said in the video, but rather Americium-241. Having the source sit like that with the steel shield still on top, it will accomplish absolutely nothing. Some UV LEDs sitting near the trigger tubes will actually help them fire in the dark.
Im happy im not the only one who noticed how absolutely pointless putting a sealed up source near the thing is, especially considering that it is an alpha emitter so even if it were not sealed it would still achieve exactly nothing.
Am-241 has an associated gamma emission.
That transformer is a work of art all by itself.
A lot of old Soviet stuff shows a level of design that looks cool but doesn’t quite make sense. Like, are those cooling fins? If so, why are they so narrow and long (bad heat conductivity)? Are they some sort of extra air core windings? Magnetic field traps? Why are they looped? Etc. You could come up with all sorts of rational sounding reasons, but the reality is that they’re often just superfluous features that do little or nothing.
It’s because Soviet engineering worked sort-of like Lysenkoism in agriculture. Stalin was highly wary of engineers because many of the more competent ones he saw as loyalists to Lenin or the previous regimes, and being broadly competent they were “indispensable” in the sense that if you kill one, you lose a valuable asset. Hence why the competent engineers maintained a level of authority that Stalin didn’t quite like, and as a response the education system itself was “reformed” to train new engineers in a rather narrow way – people were taught high level skills in rather narrow fields according to rules and theories that were given from above and told not to deviate. That way if you kill one, you can always pick a new one off the school bench, and they would perform the same. No more people with broad high level skills that would become politically dangerous and question your authority. The nail that sticks up gets hammered down. The idea was that these people were supposed to be gears in a machine, easily replaceable and reproducible in great numbers.
Of course, you can’t teach creativity, curiosity and high intelligence, so there’s always going to be people who are just better at it – or better at faking it and brown-nosing their superiors. That’s where “Lysenkoism” comes in: the stuff that they were taught not to question, like design rules that were partially based on thinking by “experts” who were also narrowly educated or incompetent. For example, the idea that a magnetic field in a motor or solenoid needs a long path of iron to “pick up speed”. In reality that was more a result of early manufacturing techniques than any sound theory – the style of construction was simply rationalized backwards to justify not changing your methods.
Where they didn’t know stuff they just had to wing it. Make something that sounds plausible even if it didn’t really work. Magical thinking, or “that ought to work”, or just imitating others. Non-experts like the political authorities wouldn’t know the difference anyways. The people then held on to their beliefs as if some sort of magic tricks that only they knew – exactly to make themselves indispensable against authority. Inevitably, people learned the hard way what didn’t work, and what had to be secretly replaced and re-designed despite commands to do otherwise. The system accepted these solutions where needed and quietly rolled them in the official canon.
But the sort of weird design quirks remained, as something of a “you must have this because professor so-and-so told us that it works this way.” Since only professor so-and-so understands why this is so, they cannot be easily replaced, because the system is relying on them to function. Rather than becoming indispensable by being competent, a lot of high level experts made themselves important by myth and political connections, and the system turned a blind eye to the difference.
You still see this same effect in play when it comes to exchange students and visiting experts from China, where they set up some experiment or device, and you question them on why they’ve implemented some feature or why they haven’t accounted for X, Y or Z. They argue for a bit, and when they run out of arguments they get angry and say “You go read book!”, and the book is the one written by their professor. If they embarrass the professor by doing something else, the professor starts to look incompetent to the higher authorities. When something works, it’s because the professor was smart, and when something doesn’t it’s the students’ fault for doing it wrong. The lesson being, never try to punch up, always punch down.
The fins on the transformer is for cooling. Oil naturally circulates trough by means of convection. The model is of a substation transformer that is 100 times the size, so the cooling pipes is that much larger in that case as well.
If you look up ONAN substation transformers, they usually appear with denser arrays of closed rectangular fins to increase the surface area and improve the chimney effect to lift air through the stack in the lack of wind, or on the opposite side of wind. That way the radiator becomes smaller and easier to manufacture, and more effective in various conditions.
However, when you look at common textbook images of such cooling systems, they do indeed show the kind of narrow looped “ears” around the transformer for the ease of illustrating the working principle.
Example:
https://circuitglobe.com/cooling-of-transfomer-and-methods-of-cooling.html#OilNaturalAirNatural(ONAN)
Versus:
https://www.electricalclassroom.com/transformer-cooling-methods/#10-oil-natural-air-natural-onan-or-oa-cooling
If one is going by the textbook and not questioning the point or thinking further to do any optimization, which design do you think they would pick?
Crazy that you did this is just ordered all the parts to build one of these. Did you use this https://pa3fwm.nl/projects/neonclock2/ guide?