Message-ID: <000501c244f0$cf36a560$2e734ac3@pcuser>
From: "Hugh Burnham" <g6tmk@thersgb.net>
To: rsgb_lf_group@blacksheep.org
References: <000101c240bb$f5237980$2c0e073e@main> <012a01c24224$5e5cef80$9c2cfd3e@default>
Subject: LF: Re: Low Energy Light Bulbs
Date: Thu, 15 Aug 2002 22:42:37 +0100
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Hi Tracey

I have a house full of Low Energy lamps, of various manufacture, Ring,
GEC, Osram, Philips, Ikea, and not noticed any problems with noise on VLF.

Where the ballast is built into the lamp, there is very little lead length
to radiate - the situation might be different if the lamps are mounted
remotely from an electronic ballast.

Many homes and businesses use Low Voltage lighting - 12 V halogen lamps
powered by transformers.
Where these systems employ "electronic" transformers, the potential for
interferance is very great,
as the currents in the cables are quite high.

I looked at a Ring DET-65 dimmable Electronic Transformer a few years ago,
and found it produced a 23kHz square wave, with a 100Hz envelope. On a
spectrum Analyser this produced an impressive comb of frequencies going
upwards from 23kHz. The circuit was a two transistor power oscillator, and
the frequency drifted all over the place with load and temperature. The
output waveform had a peak voltage of 18V and would drive up to 50W of 12V
lamps - so quite a bit of chopped current could flow.

It seemed to me that the wiring between the transformer and the
lightfittings would radiate horribly. The length of the cable between
transformer
and lamps would depend on the building and who wired them up !

I don't want them anywhere near my house, especially when you can buy
toroidal transformers that do the same job at 50Hz !

73
Hugh Burnham  M0WYE