Expected life-span of Ice-Tube clock

[wildtang3nt]

Now that I've built my clock and I'm completely happy with it's operation, I am wondering how long it is going to last. What is the expected life-span of the IV-18 tube, has anybody's clock died yet? I'm keeping my brightness and auto-dim/off settings pretty conservative to extend life as much as possible.

[adafruit_support_bill]

VFD tubes do have a finite life span. But I have not heard any reports of Ice Tube Displays dying yet. My son has had his going for at least 4 years. I'm sure there are older ones out there.

[wildtang3nt]

Well, 4-5 years should more than suffice I think, thanks for the answer

[jarchie]

According to the Ice Tube Clock FAQ,

[t]he life should be 10+ years. Keeping the display dim will likely extend the life. The tube will slowly get dimmer as the phosphor degrades. The tubes are 'new old stock' from around the mid 90's.

These tubes were meant for use in calculators, and according to the specifications the tubes should last at least 10,000 hours or just over a year. But the Ice Tube Clock does not drive the IV-18 tube anywhere near specifications. (I'm linking to the actual specifications, but they are in Russian. If anyone can read Russian, PLEASE correct me if I've made mistakes.) If the tubes are driven to specifications, they are much, much brighter than in the Ice Tube Clock. I'm guessing these tubes were intended to be easily readable in direct sunlight.

The primary mode of failure is phosphor degradation, but since the Ice Tube Clock is much, much dimmer than an IV-18 driven to specifications, phosphor degradation should be greatly reduced. Thus, I suspect the estimate of 10+ years is reasonable. Personally I would guess that the expected life of an Ice Tube Clock's IV-18 would be between 5-15 years, and I would guess 10-20 years if either (1) you would be willing to tolerate a fairly dim display, or (2) you would be willing to use an alternative firmware, like xmas-icetube, which provides options to increase display brightness to compensate for fading phosphors.

Another concern is that the Ice Tube Clock drives the IV-18 filament with direct current, which is much more damaging than alternating current--the usual way to drive VFD filaments. Personally I don't think this will reduce tube life, but neutron spin--and perhaps others--disagree with me. I've debated this point in another thread.

Finally, it's difficult to determine the lifetime of any NOS part, because with any old parts there may be unforeseen problems...

The bottom line is that I have no firm idea of how long the IV-18 should last in an Ice Tube Clock. But it seems like you're happy with a tube life of 4-5 years, and that's great! I would bet good money that your tube will last longer than that.