Dekatron powered-on lifespan/duration

[John Perkins]

Hi, are there any rule-of-thumb upper limits for dekatrons either:

powered-on spinning time?

holding a single value?

I'm interested in using them for a clock.

[gregebert]

My big clock has an A101 spinning at 1 rev/second, and has been going 24/7 for the past 3 years. No hint of degradation.

[Mike Mitchell]

My clock has been running constantly for about two years. The zero cathode in the tens-of-hours digit is on for eighteen hours a day. It is now noticeably shorter than the other cathodes,

as its metal has been sputtered away. It still works, but I've recently re-wired it so all the even cathodes are zero and the odd cathodes are one. This will let the clock randomly choose a 

cathode to represent zero, extending the life of that tube.

I'm using A101 tubes for all the counting, no microprocessors or other integrated circuits.

My cathode current is a bit on the low side (~0.33 ma), but still within spec. I might get longer life out of more current, as more of the cathode would glow.

But then again with more of the cathode glowing I'd get more sputtering, which would shorten the life.

When I actually have to replace a tube I'll first try changing the current-limiting resistor to bring the current to the "typical" value (0.4ma).

https://www.youtube.com/watch?v=pK276xZWyo4 

[threeneurons]

I've built most of my nixie clocks around 2003 to 2005. All but one use a dekatron, as a "pendulum". Most of those had the dekatron replaced once. The tube was still functional, but the glass was getting heavily "silvered". Those clocks used a GC10B, or a 6802.

On the other hand, I have 3 dekatron "dohickies" running in my office. One has a DK23, another a GC10A, and the third a GC10B. The ones using the DK23 and GC10A, have been running 24/7 for over 5 years, with no sign of silvering. The GC10B unit has only been running about a year, so its to soon to call. I also have a 6909 running in a simple pendulum circuit, that's been running for close to 8 years, 24/7. The 6909 is a high speed, which are notorious, for being duds. But the glass is this clean on that one !  

[gregebert]

I forgot to mention, I have another project underway with 36 dekatrons (I call it a tridecahexadekatron...try pronouncing that one...). I dont intend to run it 24/7, but with so many tubes I'd expect periodic failures.

I have no idea what to expect from this gizmo. It might look really stupid, and I'll probably spend too much time programming patterns in search of something hypnotic.

This nixie hobby sure does weird things to my head.