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 <[EMAIL PROTECTED]> 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 _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
