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
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