On 27 Sep 2002, at 11:01, John Teffer wrote: > > You haven't specified what you mean by 'unplugging the computer', but it may > > be the monitor that is causing the whine. I'm not a CRT guy, but many TV > > sets have an auditable high frequency whine from some of the sync/control > > electronics. Generally speaking, this is not noticeable with TV's due to the > > volume of the audio and the distance the view is from the set. However, > > computer monitors are 'up close and personal'. > > Nope, the noise is definitely coming from the power supply, I have tried > with the monitor off, and being a high frequency noise, it is pretty easy to > localize. >
I have similar problems with my Ethernet hub/switch: a very annoying high pitch hiss from its poer supply. Switching power supplies are usually designed to operate at frequencies above 20 kHz, exactly to avoid emitting audible frequencies. <SCAREMONGER> Perhaps yours is getting old and hence some components (esp. capacitors) are changing their parameters, causing the frequency to drift. </SCAREMONGER> Mind you, I'd expect a capacitor to lose capacitance, which should cause the frequency to go *up*. Disclaimer: my Electronics classes were a long time ago. -- Ceci n'est pas un .signature -- 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
