In article , "Ron G"
wrote:

One of the computers in my office had an integrated sound card, and
periodically, it would start a variable rate ch ch ch ticking sound- for
a couple seconds, and then it would go away - happened once or twice
most days. That building was practically a Faraday cage - so I'm sure
it was internal to the computer.

Ahhhh yes, how well I remember building Faraday cages when I worked in a
Research Lab. :-)

I would orient it on a wooden step-ladder, midway between floor and ceiling,
then turn and tilt until I could neutralize out the electrostatic field of
the earth.

Then, the small electronic object I had inside the Cage, could be tested
without an interfering quiescent electrostatic field.

I don't understand the orientation part of the post. A Faraday cage is
just an electrostatic shield and has nothing to do with the earth¹s
magnetic field.

Your cage must have been more than a Faraday cage.

--
Telamon
Ventura, California