John Doe wrote in
. net:

Don't believe everything you read.

Experience is the best teacher.

In other words, LEDs suck for bright light sources.

However, the hype is good for selling them to fools over the
TV/Internet. Like that one guy selling LED light bulbs on TV (USA). He
doesn't explicitly say that they're bright as a lightbulb, but they
are in a lightbulb package and used in the commercial as if they were
a lightbulb. Some people probably fall for that.


In your infinite wisdom, how do you explain this?

http://www.cree.com/products/xlamp.asp

NIST confim the brightness, so you don't have to believe the 'hype', you
only have to ask a few basic technical questions: How efficient is it?
Is there enough light to fit purpose at given cost?


"LED luminaires can only be considered high efficacy if the LED can be
tested (according to UL) to be at least 40 lm/W on the line voltage input
side of any power supply or other device.” Otherwise the fixture is not
considered high efficacy."
Source: http://www.icfi.com/Markets/Energy/d...d-lighting.pdf


Light Type: lm/WW CRI Life (hrs)
Incandescent 17 100 3k
Halogen 20 100 10k
Cree XLamp 7090 XR 48 80 50k
T12 flourescent 60 75-85 20k
Metal halide 70 70 20k
Cree XLamp 7090 XR-E 70 80 50k
T8 flourescent 74 75-85 20k
High-pressure sodium 91 22 20k
Low-pressure sodium 120 5 18k
Source: http://www.cree.com/products/pdf/XLamp7090XR-Esheet.pdf

Even if you lose nearly half the light you can still claim high efficiency
to UL standards given the 95% efficient power converters made to run LED
lamps. It would be a poor luminaire that lost that much.

As for actual light output, newer LED's put out 176 lumens or more. That's
still a tad short of what's wanted in many cases, but not by much. 7 to 10
emitters would match a standard 100W incandescent (7 for the 240V type, 10
for the 110V type). Given that the cost of the first CFL's was around £26
in the UK, maybe £40 in todays money, that puts LED's in a good position,
you can get a lot better device for a lot less than that, even now, and
it's improving fast, a lot faster than the time CFL's took to develop, and
there are probably more ways to cut costs without sacrificing safety.

It would take only a fourfold increase in output from a single emitter at
same cost to make them compete with any other light source for domestic
use, and I think we'll only need to wait a few months for that.