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From: news@pasteur.Berkeley.EDU (Six o'clock News)
Newsgroups: misc.consumers.house,sci.electronics
Subject: Low Voltage lighting (Was:Re: compact fluorescent fixtures)
Message-ID: <9949@pasteur.Berkeley.EDU>
Date: 27 Dec 90 17:51:51 GMT
References: <1990Dec19.194340.7427@amd.com> <9624@ncar.ucar.edu> <1990Dec20.201931.14289@amd.com>
Reply-To: charless@cory.Berkeley.EDU
Organization: University of California, Berkeley
Lines: 34

>In article <9624@ncar.ucar.edu> hpoppe@ncar.ucar.edu (Herb Poppe) writes:
>|Does the "LV" stand for "Low Voltage"; if so, what is the voltage?
>
>Yes, 12 V. I don't know if it's AC or DC.
>
>The lamp has a power supply/transformer which takes 120 VAC
>and converts it to 12 V. (I don't know if it's really a
>transformer or some cute solid state thing, it does say not
>to use it on a regular lamp dimmer so I suspect it's SS in some
>way.)
>
From: charless@cory.Berkeley.EDU (Charles R. Sullivan)
Path: cory.Berkeley.EDU!charless

This doesn't indicate whether it is SS or not.  Transformers can have serious
problems when driven by the output of a 'normal' dimmer.  This is because the
dimmer can be somewhat assymetric, and put some dc voltage on the transformer
primary.  Since the primary is nearly a short for dc, it draws lots of current,
perhaps the core saturates, and the transformer can overheat, a serious fire
hazard.  

'SS transformers,' which are usually a rectifier, followed by a 25kHz inverter,
followed by a high frequency transformer, and usually put out 25kHz ac to the 
lamp, have other problems on normal dimmers, notably flickering, acoustic noise
and possibly shortened life of the SS transformer and the dimmer.

*****Warning: Blatant commercial plug follows.******

Dimming both types is possible--just make sure you use a dimmer designed for 
that purpose.  The company I used to work for, Lutron Electronics, makes both
types in a variety of styles.  Call 800 433 3334 (800 523 9466 in PA) for more
info.

Charlie Sullivan                                   charless@cory.berkeley.edu