In article ,
JohnR66 wrote:

"Percival P. Cassidy" wrote in message
...
On 01/17/09 06:18 pm Ed Pawlowski wrote:

"Percival P. wrote in message
...
My attention has just been drawn to the following document:

http://www.lrc.rpi.edu/programs/NLPI.../SR_SB_CFL.pdf

Note that although the original report is older, this .PDF includes
supplements through 2005.

This seems to show that Osram/Sylvania have the shortest life and a
significant deterioration in light output during that short life,

GE appear to be the best. I think they are available at Wal-Mart and
Sam's
Club.

In terms of CFL technology, 2005 is almost pre-historic. Most new bulbs
are
quite nice. I hated and refused to use them years ago but like the
bright
white of some now.

Probably true that a lot has changed since 2005. But most of the CFLs I've
bought have been Sylvania, and they haven't lasted particularly long.
Perhaps that's a Sylvania thing: I had some Sylvania incandescents that
popped as soon as I switched on and at least on more out of the same pack
that lasted only a couple of days.

I have just bought some "Lights of America" brand 45-watt-equivalent LED
bulbs (power consumption only 3.5W) intended for use in accent lights: a
nice white light and no warm-up delay.

Perce

Lights of America products are typically poorly engineered junk. Also beware
of cheap LED lights. They will fade within a few hundred hours of use. These
are the type made from clusters of those 5mm indicatoer style LEDs. The
bulbs are usually under $25. The only good LED bulbs are expensive and use
high power LEDs, like the Cree XR-E emitter.

Colored LEDs usually last a good long time, if they are blue,
blue-green, green, yellow, orange or red. The often-stated 100,000 hours
has a high rate of "turning out true" for those.

White ones have a phosphor that is subject to fading - better low power
ones have "half-life" maybe 10,000 hours, merely fair ones a few thousand
hours, and well-engineered major brand (such as Lumileds) heatsinkable
high power ones achieve 50,000 hours with only 30% fading supposedly (or
as a projection, latest "flagship" ones have existed less than 50,000
hours), provided they are operated "reasonably conservatively" in amount
of current and in terms of temperature - as in chip/"junction" temperature
maybe 30 degrees C cooler than "absolute maximum" or 85 degrees C
(whichever is hotter).
Pink and purple ones also have phosphor. Violet ones (which is
distinguished from purple by being a spectral color) usually have another
life-shortening issue - nearly-UV wavelength and nearby UV also emited
degrade most plastic chip-encapsulating materials at close range, and
"half-life" is all-too-often a few hundred to optimistically a couple
thousand hours. (Thankfully, most purple LED "holiday lights" use white
LEDs within purple shells - and glow with a color a bit more like
"lavendar" than like "deep violet").

- Don Klipstein )