Re: [VAL] Re: LED lamps

[root <geraldj@xxxxxxxxxxx>]

> I love LEDs, but my personal opinion is that they can
> still be tricky to use for general illumination.  But,
> as Dr. J said, the rate of new product introduction is
> amazing.  White LEDs are now available in ratings up
> to 5 watts!  But, they tend to be very tightly
> focused, and some don't like the color/spectral
> output.

The last announcement in Electronic Products was for a LED with a 20
degree spread. Really broad for a LED with illumination intensity yet. I
didn't find a price yet.

> 
> You may be pleased to know that halogen bulbs provide
> some of the highest efficiencies obtainable for
> general illumination purposes.  Next time you're in
> the home improvement store, compare the output (in
> lumens) of standard and halogen bulbs of identical
> wattage.  The difference can be dramatic.  Small
> halogen bulbs are available in all sorts of
> configurations.  Just make sure to use lower wattages
> if your goal is power savings.
> 

Watch out for the high temperature of the quartz-halide / halogen lamp.
It has high efficiency because the envelope is run at a high enough
temperature to evaporate tungsten from the quartz back to the filament.
That keeps the filament from evaporating so fast which allows it to be
run at a higher temperature and keeps the envelope from clouding up. But
to do that the quartz envelope (glass would melt) has to operate hot
enough to ignite fabrics that get too close. Floor lamps sometimes sold
as "torchiers" turned into torches when drapes fell on them or they
dried out close spaced ceilings and ignited them. Those used 300 watt
halogen lamps.

The slight bit of skin oil left on a halogen lamp will cause lamp
destruction as the oil gets converted to carbon and overheats the
quartz. So you have to never touch that envelope or wash it with a good
residue free oil solvent.

The efficiency of a halogen lamp is still quite a bit poorer than that
of a fluorescent lamp with ballast.

> 
> Jon in SC
> 68 Overlander


Gerald J., WBCCI #5623, VAC, Electrical Engineer