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From: durham@w2xo.pgh.pa.us (Jim Durham)
Newsgroups: sci.electronics
Subject: Re: light bulbs buzz when dimmed
Message-ID: <142@w2xo.pgh.pa.us>
Date: 6 Apr 91 04:28:08 GMT
References: <1991Apr2.162037@maximo.enet.dec.com>
Reply-To: durham@sei.cmu.edu (Jim Durham)
Organization: Jim's Basement, Gibsonia, PA
Lines: 21

In article <1991Apr2.162037@maximo.enet.dec.com> ajf@maximo.enet.dec.com (Adam J Felson) writes:
>I have a pair of floor lamps hooked up to a single dimmer.  They use
>6" spherical incandecant light bulbs.  The problem is that they make
>an annoying buzz when dimed.  Is there a better circuit for dimming
>the bulbs that will prevent that !@#$%^&*&^%$# buzz?
> 
>__a__d__a__m__

I work at a television station where we have the same problems with dimming
studio lights. The problem is the rise time of the scr dimmer circuits.
To get non-buzzing light filaments, you need a rise time on the scr
waveform of 800+ nanoseconds. We have some 180ns dimmers and they
buzz like crazy when dimmed.

A quiet way to dim lights is with a small variac or autotransformer.
These are quite often available at flea markets or hamfests and could
be put in a little metal box.

Good Luck!

-Jim  (durham@w2xo.pgh.pa.us)