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From: tom@syssoft.com (Rodentia)
Newsgroups: sci.electronics
Subject: Re: light bulbs buzz when dimmed
Message-ID: <1991Apr22.161357.23840@syssoft.com>
Date: 22 Apr 91 16:13:57 GMT
References: <1991Apr2.162037@maximo.enet.dec.com> <1991Apr3.223655.18202@cbnewse.att.com> <7893@jhunix.HCF.JHU.EDU> <1991Apr4.031246.14045@athena.cs.uga.edu>
Reply-To: tom@syssoft.com (Rodentia)
Organization: Systems & Software, Inc., Irvine, CA
Lines: 17

I posted this question before, but the news feed has been very sporadic
here, so please reply by e-mail even if you followup (my Reply-To:
should now be tom@syssoft.com (even that was broke)).

To summarize:  If dimming by chopping cycles or half cycles of the 60Hz
waveform causes audio noise based on these 60 or 120 Hz fundamentals, 
couldn't the noise be made inaudible by doing the chopping at some
inaudible frequency such as 20KHz?  Would this be less efficient or
more expensive than the other (transformer based, I believe) approach
mentioned in this forum?  Or would it just not work?

Thank you for your attention.
-- 
Thomas Roden                                      | tom@syssoft.com
Systems and Software, Inc.                        | Voice: (714) 833-1700 x454 
"If the Beagle had sailed here, Darwin would have | FAX:   (714) 833-1900
come up with a different theory altogether." - me |