On Thursday, July 6, 2017 at 9:51:54 AM UTC-4, Phil Hobbs wrote:
On 07/06/2017 08:35 AM, wrote:
On Thursday, July 6, 2017 at 3:19:34 AM UTC-4, frank wrote:
Phil Hobbs wrote:


Maybe Barkhausen oscillation (aka the Barkhausen-Kurtz effect). This
used to show up in old-fashioned incandescent light bulbs that were
evacuated instead of argon-filled.

according to a wikipedia article, the Barkhausen-Kurz oscillator used
triodes. So I'm still puzzled.
I'll try to make a test setup with constant current on a GDT and try
to measure the frequency of the oscillation.

Frank

Not knowing Barkhausen-Kurz from Berkinstocks, I think Phil means it
has to do with the time delay. Enough gain and a time delay leads to
oscillations. (hmm just like in thermal control loops.)

George H.


No, it's a coupled plasma/surface effect. It's really cool. It peaks
down around a few tenths of a millitorr, but it's still appreciable at
higher pressures.

The light bulb thing was discovered by somebody turning on an
incandescent lamp and wiping out his reception.

Huh, OK... Get any sort of link?
B-K tube,
https://en.wikipedia.org/wiki/Barkha...80%93Kurz_tube
sounds like a delay... like a reflex klystron.

Is it a surface plasmon thing?
https://en.wikipedia.org/wiki/Surface_plasmon_resonance

Back to Frank, Can you do an I-V (at DC) to see if there is
negative resistance. (i've never looked at a negative
resistance so I don't really know if I'm asking the right
question.)

George H.



I don't know if the pressure in the transient suppressor is low enough
for Barkhausen--if not, it's probably the neon bulb oscillation as
others have said.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

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