Re: Lutron Diva dimmer broken - THANKS!

M Q wrote:



Jeff Wisnia wrote:

...

Well, I followed through and bought some 150 watt bulbs yesterday. While I was at the store looking at the lumen ratings of frosted incandescents I noticed that the 150 watt output of a "three way" 50-100-150 watt bulb was also considerably lower than that of the plain 150 watter.

Yes, a "3-way" is just a 50 W and a 100 W in the same globe.


I replaced the "Y" adaptor and its two 75 watt bulbs in just one of our two living room table lamps with a 150 watt bulb.

the results were pretty dramatic, the lamp with the 150 watt bulb was noticably brighter, so I put a 150 watter in the other one too.

Now I need someone to understand why the single 150 watt incandescent puts out 20 percent more lumens than the pair of 75 watt bulbs. (Are you reading Don Klipstein?) I'm guessing it might have something to do with more thermal energy being tossed away through four filament supports than through two, or something like that.


I can give you a partial answer. The filaments in higher wattage
bulbs are designed to run at a higher temperature. At the higher
temperatures, more of the radiated energy is in the visible light
portion of the spectrum (see http://en.wikipedia.org/wiki/Black_body )
(however still only around 3-5%). Why don't we just run all
bulbs hotter? That dramatically decreases the lifetime of the
filament. Why can we get away with running higher wattage
filaments hooter than lower wattage ones? That's the part that I
don't know.


Maybe another reason is because the bases of both bulbs are the same diameter but the 75 watt bulb is physically smaller than the 150 watt one. That puts its filament closer to its the base which makes the base obscures a larger solid angle in the total sphere of radiation, thus blocking a greater percentage of the visible light?

Jeff

<snipped>

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10^12 furlongs per fortnight.

.

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