>Date: Thu, 26 Sep 2002 08:49:52 -0500 >Subject: Re: [SM] Newbie questions-O.T. >From: John Teffer <[EMAIL PROTECTED]> >Message-ID: <[EMAIL PROTECTED]> >In-Reply-To: <[EMAIL PROTECTED]> > >> From: Paul Corsa <[EMAIL PROTECTED]> >> >> The humming sound may be a medical condition. Especially if no one else >> hears it. Ringing in the ears is a common thing, more so in people with >> Attention Defficet Disorder. It has to do with the size and shape of the >> ear cannal, which is hereditary. I belive it is called Tintinitus(sp)? >> Are you the only person who hears the sound from your computer when it >> is turned off? Paul > >Yeah, I've heard of tinnitus, (thanks dictionary.com) - From a public >service video I found one day at the dump. (Where most of my computers come >from.) It had all sorts of famous aging rock and roll stars talking about >how they sure wish that they'd worn ear plugs in their younger days. > >Since this sound definitely starts and stops when I plug in and unplug the >computer, I don't think it's all in my head. My girlfriend can't hear it, >but then again she "almost went deaf as a child" from several ear >infections, or at least that's what she always says when I complain that >she's not listening to me... > >It doesn't seem to bother the two cats we live with either, one of them has >found the flat top of the S900 a perfect spot from which to survey his >domain. > There are two possible sources of this high frequency "noise", one more likely to be heard by you than the other. 1. The Switching Power Supply used in the computer typically operates at a switching frequency of around 20kHz. This is audible to some with exceptional hearing in the high frequency range. 2. The flyback transformer in the CRT Monitor operates at the horizontal frequency of the display (typically 35kHz or higher). This is totally inaudible to a human ear. The way to determine the difference: Turn off (unplug) the monitor only while the computer is on. But most likely, the "noise" is coming from the power supply, and the only solution (not guaranteed to work) would be to replace it in the hope that you'd get one that operated at a slightly higher frequency that you would not hear. If, however, the sound is coming from the monitor, (like the TV that someone else reported they could "hear"), it is possible that you are hearing a sub-harmonic of the horizontal frequency caused by the laminations or windings of the transformer vibrating. Cats do not have the HF sensitivity of dogs. A dog would be able to hear this, and would probably stay as far away as possible.
-- SuperMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | Service & Replacement Parts [EMAIL PROTECTED] | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> SuperMacs list info: <http://lowendmac.com/supermacs/list.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/supermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
