Date: Tue, 10 Jun 2008 12:47:13 +0930 From: Wayne Sierke <ws@au.dyndns.ws> To: Bob McConnell <rvm@CBORD.com> Cc: James <james@icionline.ca>, cpghost <cpghost@cordula.ws>, freebsd-questions@freebsd.org Subject: RE: Whine when EHCI controller enabled in BIOS Message-ID: <1213067833.95829.14.camel@predator-ii.buffyverse> In-Reply-To: <FF8482A96323694490C194BABEAC24A002D7B752@Email.cbord.com> References: <7039ada60806082040s36afc2c8n4698402ac5d4ff29@mail.gmail.com> <20080609111200.75197d59@epia-2.farid-hajji.net> <FF8482A96323694490C194BABEAC24A002D7B752@Email.cbord.com>
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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@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 escaping gas! Wayne
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