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Message-ID: <003601c9a041$990c2c40$0900a8c0@AM>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
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Date: Sun, 8 Mar 2009 22:53:17 -0000
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Subject: LF: Re: RE: Re: energy saving bulbs
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Hi Chris with respect, the articles and ads and PR don't talk about light
output but "saving energy", as I said they are not considered "domestically
fashionable" but strip lights still are more effective in light output to
energy input. As to the waste energy when you dont need the "extra" warmth,
this is fairly negligible because it only occurs in the summer when you dont
need lights for long anyway. How many still waste energy by having the
freezer in the garage or uninsulated utility room? .Its like the drive to
get you unplugging phone chargers when not in use, mine doesn't show on a
power meter, which means well below a watt....I must measure it accurately
sometime on my true rms meter. Better planning and reducing the kettle
boils, or wash loads by one a week. or washing the dishes by hand once a
week, would save more power. Why wont we accept street lights being put off
at midnight?? 100s of kWhrs are consumed so a few people can walk home in
towns after midnight. Don't get me wrong CFLs are a good idea but not so
all-fired marvellous as we would be had to believe....everyone ain't a radio
amateur though :-))

As to LEDs they look interesting and are now approching CFLs but are still
behind strip lights for "efficiency". I reckon one problem might be they are
low voltage devices hence the need for the switching voltage reducer. That
means also that they are high current units and then there are big IR losses
to heat too. I suppose series strings could be used but there might be a
reliability problem inherent in running devices in series. As I said I have
one make of CFLs that wipe 136kHz and probably upwards even with the antenna
10m away, But I havent found trouble with the Philips branded product yet on
any frequency I listened. I still worry a little about the ozone smell but I
dont know whether this is an isolated occurance yet. But that is not an
exhaustive test they may just be different. I used to have a noisy tube
light, bad on 160m, but presently used ones are surprisingly clean, unless
you get up very close....within a foot or so.

Cheers de Alan G3NYK

----- Original Message -----
From: "Chris Trayner" <C.Trayner@leeds.ac.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Sunday, March 08, 2009 8:32 PM
Subject: LF: RE: Re: energy saving bulbs


Dear All,


Thanks, Alan, for your thoughts.

> The tale that filament lamps are inefficient is a myth !! All the energy
fed
to the bulb is converted into radiation ! some is light and some is
heat.....a CLF just produces less heat and more light and more polution!

Well, in a sense you're right: efficiency is defined as (energy out) /
(energy in), and the conservation of energy principle implies that (in the
steady state) everything is 100% efficient ;-)
In practice, by efficiency one means (wanted energy out) / (energy in), and
when you turn on a lamp you're not necessarily cold. In engineering terms
it's better to decouple the things and have a lamp produce just light.
- Electricity is generated at something like 1/3 efficiency overall, and
using fuels to generate heat directly is better.
- The idea that waste heat can be used is relevant in cold climates, but
presumably less so nearer the equator.


I also wonder whether these discussions may be useful only for a limited
time. I get the impression that LED room lighting may be starting to replace
other forms. Is this right? How does its efficiency compare with other
forms? Opinions, anyone?

If LED room lighting does come in, it raises new problems of interference
relevant to LF. One thinks of LEDs as being innocent DC devices fed via a
resistor. But modern designs often turn them on and off at frequencies in
the kHz range, generating harmonics going into the lower radio bands. This
has been known for some time in the cave radio community, where 87kHz is the
most commonly used band. The Cave Radio Journal has also documented
interference with 2m and 70cm amateur band handhelds. This can work both
ways - if I speak into a PMR446 radio it quenches my LED helmet lamp - the
Empire strikes back!

Cave radio experience is that interference from LED lamps is very short
range, but these lamps are driven from local batteries. Will mains-driven
ones radiate from the wiring? Do vehicle LEDs cause interference? Does
anyone have any experience of this?


73,
Chris G4OKW

-----------------------------
Dr Chris Trayner
School of Electronic & Electrical Engineering,
The University of Leeds,
Leeds LS2 9JT, United Kingdom
Tel: +44 113 34 32053
Fax: +44 113 34 32032