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.

Best----
Ron


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