Re: N:Vision CFL's

[Marc_F_Hult <MFHult@xxxxxxxxxxxxxxxxxxxxx>]

On Sat, 24 Mar 2007 16:34:09 -0400, "Slammer" <mjinks@xxxxxxxxxxxxx> wrote in
message  <v96dnSh9FJ6JFpjbnZ2dnUVZ_uKknZ2d@xxxxxxxxxxxx>:

>"Marc_F_Hult" <MFHult@xxxxxxxxxxxxxxxxxxxxx> wrote in message >
>>
>> The warmup period for the 2700K and 3500K is completely negligible
>> starting
>> from room temperature (I previously posted data showing rapid warm-up
>> starting at 0F (-18C)).
>>
>> As the physics would suggest, the 5500K takes longer to warm up.
>
>Huh?
>
>The color temperature of a light source is determined by comparing its hue
>with a theoretical, heated black-body radiator. The Kelvin temperature at
>which the heated black-body radiator matches the hue of the light source is
>that source's color temperature, and it is directly related to Planck's law
>of black body  radiation.
>
>An incandescent light is very close to being a black-body radiator. However,
>many other light sources, such as fluorescent lamps, do not emit radiation
>in the form of a black-body curve, and are assigned what is known as a
>correlated color  temperature (CCT), which is the color temperature of a
>black body which most closely matches the lamp's perceived color. Because
>such an approximation is not required for incandescent light, the CCT for an
>incandescent light is simply its unadjusted Kelvin
>value, derived from the comparison to a heated black-body radiator.
>
>
>Michael

Huh huh. Instead of plagiarizing wikipedia, why not cite it?

http://en.wikipedia.org/wiki/Color_temperature

While what you quote without attribution is well and good, as you point out,
it is not the physics involved.

Please refer to the spectra for the n:vision CFLs at the url I posted in the
part of this post you deleted and ask yourself what the difference is between
the spectrometer plot of an N:Vision "Bright White" 3500°K CFL. and an
N:Vision "Daylight" 5500°K CFL

http://ledmuseum.home.att.net/spectra7.htm

That's where the answer lies and not in your description of the force-fit of
fluorescent spectrum to a black-body approximation.

This would be a good question to ask in sci.engr.lighting. The general answer
you/we would get would deal with how different actual _lamp_ temperatures (in
°C)  affect the fluorescence, and what different manufacturers do with
voltages and mercury pressures/concentrations and fluorescent compounds to
create different spectral mixes.

When all is said and done, IIRC, short wavelength spectra require higher
physical temperatures, hence my statement "As the physics would suggest, the
5500K takes longer to warm up" to reach maximum output.

But it's been more than a decade since I actually worked with this in any
detail so you might consider doing a google search and(or) quizzing the
s.e.l. newsgroup and reporting back.

...Marc
Marc_F_Hult
www.EControl.org