Thread: Strange problem with low energy light bulb
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Lostgallifreyan Lostgallifreyan is offline
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Default LEDs as lamp replacements
(Don Klipstein) wrote in
:

I expect about 6.7 watts in the case of a 1710 lumen 100W
incandescent,
if the ellipsoidal mirror is a whole ellipsoid and 100% reflective and
the dichroic filter passes all 400-700 nm light.

As for the rest, approximately or "educated guesses":

UV passing through the glass: .12%
UV absorbed by the glass: .02%

Heat conducted/convected from the filament: ~13%

IR passing through the glass: ~60%
IR absorbed by the glass: ~20.16% ("rounded oddly" to make figures add
to 100%)


I was trying to keep the lumens out of this entirely, but I'll buy it.
It makes me wonder what the fuss is about actually. While it's better to
get more efficiency, it seems that incandescents aren't so bad we need to
consider banning them, we just need to think more about what source we use
for a given task. As for the case to ban all but halogen types, how much
might be gained? With IR reflection to make them keep the tungsten hotter
for a given input, we get more light, but even so, is there that much
difference? Enough to say that they stay and standard incandescents go?

If LED's ever get a spectral match for a small efficient low-volt halogen,
at least the choice will be easy.
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