Nixie Clock - Time Cycle enough to protect against cathode poisoning? Without slot machine effect

[Dman777]

Hi,

I think I might of found a In-12 Clock that I like. However, it doesn't have the occasional slot machine display effect to protect it against cathode poisoning. The person that makes this kit said that it's a gimmick and not necessary because the when the clock cycles through time that is enough to protect it. Is this true?

[Joseph Bento]

I'm curious as well.

 I could see issues with the "10's" position for seconds and minutes, as the highest number it will ever see is "5."  Is that an issue if you don't care about the other numbers?  10's of hours will only see a "1" for a 12-hour clock, and up to "2" for a 24-hour clock.  Do we actually care about these other numbers?

Joe, N6DGY

[greg...@hotmail.com]

If your tubes are socketed, you can rotate them yearly. It's a bit of a pain if you have several clocks (grrr...I have 5 clocks, and one of them  has 15 tubes)

[Dman777]

Hmm...would yearly be often enough? 

 What if I only ran the clock during the day and turned it off at night? Would the on/off routine protect against cathode poisoning or does it need to be the slot effect for the electricity to burn off the gas residue? 

[greg...@hotmail.com]

I just rotated the 15 tubes in my big clock after 11 months. They display the same numeral 24/7, which I believe is the worst-case scenario for cathode poisoning.

12 tubes showed no signs of degradation

3 tubes showed slight degradation:

• A slightly dim tube is now fine after running 12 hours at nominal current
• A slightly dimmer tube is better after 12 hours at nominal current, but not quite healed. Perhaps it will take a few days
• Lastly, a '2' was not illuminating at the center. After 12 hours, it's fully illuminated, though slightly dimmer

I did not check all digits for each tube; I simply rotated them to their next position. So it is possible that other digits are damaged. After the above 3 tubes have settled-in, I will do a thorough check of all cathodes.

Conclusion ? Cathode poisoning definitely happens, though it seems to take quite awhile. It also appears to be reversible as long as it was not severe. I'll post an update in a few weeks when I do thorough testing.