Jeff Liebermann wrote:
The one that oscillated (IMG_1950.JPG) looks very much like your
original video.
https://www.youtube.com/watch?v=DeKPkG5T1xc
It would be helpful if you increased both the vertical and horizontal
gain of your photos so some detail could be seen:

that's the max vertical "gain" that I can have on the IT-3121, 0.5mA/div.


If you happen to have a few identical NE-2 lamps, put three in series
to get something close to the 200v as in the gas discharge tube. Then,
compare the displays.

I've just tried that, no oscillations.

Also, smaller JPG's please. This test does not require 12 megapixel
images.

Sorry for that, I've not plaied with the camera settings.

Here's a video of the oscillating neon lamp, the higher current is obtained
with 100k resistor, the lower current (and larger oscillations) is with
500k limiting resistor:

https://www.youtube.com/watch?v=cgObvN8xiWM