["Followup-To:" header set to alt.electronics.]
On 2005-11-04, jh wrote:

Thanks for the tip. I'll try both ideas (when I get a chance; it might
be a while) and post anything interesting. I'm hoping to eventually
(maybe after I learn more about electronics) build a reasonably
sensitive EMI-only "microphone" to use as a sort of computer
stethoscope.

Here's my idea: could a computer technician, with this tool and some
practice, hear and immediately recognize the EMI signature of a dying
power supply or other bad component, the same way an expert pilot can
instantly diagnose engine troubles just from their noises? Certainly,
many technicians recognize the distinctive sound made by some dying hard
drives; but most components don't make any noise that we can hear
naturally.

not as well as a mechanic can diagnose an automotive fault by ear.
most of the stuff that gooes on inside compputers happens at frequencies
well above the threshold of hearing.

It may be possible to diagnose developing faults with an oscilloscope but
it's generally cheaper to use a redundant system than to employ an expert
to maintain the system.


most of the noise your microphone was picking up was probably the switching
frequency of the fan and hard-drive motors.

Bye.
Jasen