I have this bathroom fixture
https://imgbox.com/iAfZpLFH
https://imgbox.com/XbRoYa9h
https://imgbox.com/nq94qM2b


It (the bathroom cabinet) was custom made in the 70s

the lamp was never replaced, and I hope it will never need to be

At first I thought this was a magnetic rapid start flurescent light, but when I had to put the fixture down for cleaning and saw a transformer, I am suspecting it might be a neon light inside

Did they ever make square flurescent tubes? I know they made circular flurescent tubes, but not sure about square ones

I am wondering this so I can find a replacment incase the light breaks on me (the transformer hums as long as I can remember, but everything still works)

Its also interesting that this light did not change color (usualy flurescent lights as they age, change color from white to yellow as something happens to the fosfor coting)

The links aren't working. Is the tube a complete square, or is it like a 2D fluorescent lamp?

Tube image is blurry, but it looks like custom made neon tube.

In fact, aging fluorescents do not change color that much (though especially halophosphate phosphors DO lose some light and drop CRI). It is more plastic parts of a luminaire yellow over time.
Neon (cold cathode) do age and dim too, but may be do this slower because of lower power loading.
You can get a replacement modern electronic neon power supply easily, as a bonus, these do not hum any more, on even conventional magnetic transformer.
Neon tube most likely runs at usual 30 milliamps, but units made for lighting specially may be rated for higher current, say, 60mA. You have to guess some way or look at transformer nameplate (if any) or measure *carefully, high voltage*.

If needed, a custom neon tube of any shape desired can be ordered from a neon maker nearby, not extremely expensive.


 

Wow, nice, I always wanted to have a neon+argon (like blue color) sign (but not sure if anyone makes theese in Slovenia and also if I could find old magnetic transformer for it (since I hate modern swich mode power supplies, cuz they produce RF interference)), never knew I already have a neon light

Here is a video of it running: https://www.youtube.com/watch?v=M63_021NPtU
not sure how to make better picture since I am not sure if this tube even comes out of there

How did you know its a neon tube and not flurescent one?