Whine when EHCI controller enabled in BIOS
ws at au.dyndns.ws
Tue Jun 10 03:32:32 UTC 2008
On Mon, 2008-06-09 at 11:27 -0400, Bob McConnell wrote:
> On Behalf Of cpghost
> > On Sun, 8 Jun 2008 21:40:17 -0600
> > James <james at icionline.ca> wrote:
> > I'm no specialist and it may be an urban legend, but from
> > what I gathered, some coils could exhibit the behavior of
> > generating those high-pitched whines when exposed to certain
> > frequencies.
> > -cpghost.
> No legends here. The horizontal sweep frequency for televisions in the
> US is 17,500 Hz. Many people could hear that whistle from cheap flyback
> transformers. Other devices would buzz, hum or rattle when they
> resonated with EM fields. Occasionally they can be heard by humans, more
> frequently they can be heard by their pets. As I have gotten older, I
> don't notice it as much.
Indeed. About 20 years ago our company produced a data logger for a
local gas utility. At one point our bright, young design engineer
replaced a linear voltage regulator with a switch-mode design - quite
novel at the time. Only thing was, the hand-wound inductor coils
inevitably emitted a hissing noise, not entirely unlike the sound of
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