On 1/26/2013 3:38 PM, Nate Nagel wrote:
On 01/26/2013 04:33 PM, wrote:
On Fri, 25 Jan 2013 12:18:45 -0600, Doug
wrote:

On Fri, 25 Jan 2013 09:22:57 -0800, Bill
wrote:

In article , says...

In another thread, it was mentioned that CFLs and LEDs
last longer than incandescent bulbs.

We all know incandescent bulbs fail due to the filaments
being made so thin that they oxidize and burn up, over time.

But, what causes CFL bulbs to fail?

And, what causes LED bulbs to fail?

Greed on the part of the manufacturers (for all light bulbs which do
not
last long). The bulb burns out, you buy a new one and they make more
money!

This bulb has worked for over 110 years...
http://en.wikipedia.org/wiki/Centennial_Light

I remember back in the 70s seeing a tour of Thomas Edison's Florida
home and they had a bulb of his burn so many hours a day since he
left. I guess it was like 50+ years then and still burning well. So
I got to believe what most people say in this thread as true.
That poor thing doesn't put out a whole lot of light either.

Take a 100 watt 120 volt bulb and run it on 80 volts - particularly
9f you can feed it DC - - the light will be a warm yellow. equivalent
to something like a 40 watt bulb - and will last for decades.


It's an efficiency thing though... say you have a 120W, 240V
incandescent running on 120V. The light out of that bulb will be dimmer
than a 60W, 120V bulb running on 120V, as the filament won't be as hot
and therefore won't glow as brightly. You're trading life for efficiency...


The graph I have goes to 90% voltage. At that point the life is
increased 50% (and rising fast). The lumens are 70%. At half voltage the
lumens would be a rather low percentage (far lower than 60W equivalent).

As you lower the voltage the spectrum shifts toward red and infrared (as
you more or less said) That means a much higher percentage is heat.

With higher voltage the spectrum moves toward blue and a higher
percentage is in the visible spectrum. Photographers used to run bulbs
at overvoltage. Stadiums sometimes did the same thing.

Last time I was in Menards they had some long life bulbs with appalling
low lumen ratings for the wattage.