On Thu, 29 Aug 2013, [email protected] wrote:
It's entirely different than the blue dots I've seen on tubes that have
been sitting on the shelf for years, because those go away after a few
minutes or hours of usage.
I suspect that's from mercury that has collected locally, and is
subsequently distributed after the tube is energized.
blue dot is due to multiplexed driver design, not due to problem in the tube.
from dieter:
The blue spots are caused by the following circumstances:
If low voltage drivers are used, as example the 74141 drivers, the cold
cathode voltage (non glowing cathode voltage) drops down to the clamping
voltage of the output transistors (70-100 Volts).
In this state the mercury slightly breaks down, slightly ionizes, and
little current flows from the anode, through all 9 non glowing cathodes
through the Z-Diodes (Driver protection diodes) to ground. And that
inonized mercury can be seen as blue spots in the tube.
That's all.
-Dan
--
You received this message because you are subscribed to the Google Groups
"neonixie-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send an email to [email protected].
To view this discussion on the web, visit
https://groups.google.com/d/msgid/neonixie-l/Pine.LNX.4.64.1308291209340.5639%40sasami.anime.net.
For more options, visit https://groups.google.com/groups/opt_out.
