Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!jhunix!ins_atge
From: ins_atge@jhunix.HCF.JHU.EDU (Thomas G Edwards)
Newsgroups: sci.electronics
Subject: Re: light bulbs buzz when dimmed
Message-ID: <7893@jhunix.HCF.JHU.EDU>
Date: 4 Apr 91 01:22:37 GMT
References: <1991Apr2.162037@maximo.enet.dec.com> <1991Apr3.223655.18202@cbnewse.att.com>
Organization: The Johns Hopkins University - HCF
Lines: 16

In article <1991Apr3.223655.18202@cbnewse.att.com> random@cbnewse.att.com (David L. Pope) writes:
>> an annoying buzz when dimed.  Is there a better circuit for dimming
>> the bulbs that will prevent that !@#$%^&*&^%$# buzz?

>and min for the bulbs you are using). The actual cause of the buzz
>is the length of the fillament in the bulbs, so maybe you could
>find large diameter bulbs designed for dimming (that is, with short
>fillaments).

O.K...but exactly why do the bulbs buzz when dimmed, but not when at
full power?  My guess on this always was there was some kind of
clamping of the waveform going on, making it look more and more like
a square-wave with associated audible harmonics?  In that case perhaps
a variable-transformer would make life better.

-Tom