From owner-freebsd-questions@FreeBSD.ORG Tue Jun 10 03:32:31 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id DF7931065673 for ; Tue, 10 Jun 2008 03:32:31 +0000 (UTC) (envelope-from ws@au.dyndns.ws) Received: from ipmail05.adl2.internode.on.net (ipmail05.adl2.internode.on.net [203.16.214.145]) by mx1.freebsd.org (Postfix) with ESMTP id 6A8CF8FC1B for ; Tue, 10 Jun 2008 03:32:31 +0000 (UTC) (envelope-from ws@au.dyndns.ws) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AmcBAL5xTUiWZWdv/2dsb2JhbAAIsCw X-IronPort-AV: E=Sophos;i="4.27,615,1204464600"; d="scan'208";a="132955063" Received: from ppp103-111.static.internode.on.net (HELO [192.168.1.128]) ([150.101.103.111]) by ipmail05.adl2.internode.on.net with ESMTP; 10 Jun 2008 12:47:16 +0930 From: Wayne Sierke To: Bob McConnell In-Reply-To: References: <7039ada60806082040s36afc2c8n4698402ac5d4ff29@mail.gmail.com> <20080609111200.75197d59@epia-2.farid-hajji.net> Content-Type: text/plain Date: Tue, 10 Jun 2008 12:47:13 +0930 Message-Id: <1213067833.95829.14.camel@predator-ii.buffyverse> Mime-Version: 1.0 X-Mailer: Evolution 2.22.2 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: James , cpghost , freebsd-questions@freebsd.org Subject: RE: Whine when EHCI controller enabled in BIOS X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 10 Jun 2008 03:32:32 -0000 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 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