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Path: utzoo!watmath!watcgl!dmmartindale
From: dmmartindale@watcgl.UUCP (Dave Martindale)
Newsgroups: net.ham-radio
Subject: Re: Noisy dimmers and fluorescent lights?
Message-ID: <1080@watcgl.UUCP>
Date: Mon, 28-Jan-85 12:30:30 EST
Article-I.D.: watcgl.1080
Posted: Mon Jan 28 12:30:30 1985
Date-Received: Tue, 29-Jan-85 05:42:45 EST
References: <942@vax135.UUCP> <143@redwood.UUCP>
Reply-To: dmmartindale@watcgl.UUCP (Dave Martindale)
Organization: U of Waterloo, Ontario
Lines: 17

Another (expensive) alternative to triac dimmers: use an autotransformer.
They're physically too large to install in an outlet box, and require
ventilation air in the higher current ratings, but they do work.

I have one controlling the reading lamp over my bed, and the computer
graphics lab here uses incandescent lamps on autotransformers as dimmers.
In both these cases, the reason was avoiding audio noise, not RFI.
Incandescent lamps driven by the waveform put out by a triac dimmer
"buzz" audibly; with the autotransformer the only sound is the
(very quiet) hum of the transformer itself.

As a side benefit, the lamp can be taken smoothly right down to zero
light output, something that just doesn't work with the triac dimmers.

When picking an appropriate size of autotransformer dimmer, remember
that incandescent lamps are not constant-impedance devices - use
the transformer ratings intended for constant-current loads.