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From: (no name) (no email)
Date: Thu Aug 19 1999 - 12:20:47 EDT
Hi Don and all,
I couldn't resist this one, since my company sells thousands of halogen (and
other) bulbs each year.
In a message dated 8/18/1999 11:58:18 PM Eastern Daylight Time,
writes:
> So the real question seems to be whether halogens are more tolerant of
higher voltages,
The answer is no, just the opposite. There are two reasons that halogens are
"brighter" then conventional lamps (we call 'em "lamps" in the stage, studio
and TV business).
One is that they have to operate at a higher color temperature (typically
3000-3200K) in order for the halogen cycle to work. Since both conventional
and halogen bulbs use a tungsten filament, this means that the halogen
filament's temperature is closer to the melting point of tungsten than a
conventional bulb (which typically operates at 2800K). Bottom line is that a
halogen bulb's life decreases more rapidly under over-voltage conditions than
a conventional bulb because of the maximum temperature of the filament. I
know of some halogen lamps which operate at 3400K, but no more. Also, because
the filament temperature is close to the melting point, thay are much more
susceptible to failure due to physical shock.
Insofar as being "brighter" for a given wattage, owing to the higher color
temperature, the light from the halogen is "bluer" (which appears whiter to
the eye) as well as "brighter" than a conventional lamp (which is "redder").
A good example of color-temperature is the sun at noon (6500K) vs sunset
(2000K)
Another advantage is that the halogen cycle keeps the internal bulb wall (we
call it the "envelope") clean whereas a conventional tungsten lamp will lose
about 50% of its output over its rated life due to tungsten being deposited
on the bulb wall.
> Speaking of lifetime, you can't touch the bulb's glass as you probably
know. Your fingerprint will cause rapid failure, so > factor that into the
replacement scenario. You just wear rubber gloves or use a paper towel if you
have to press
> them into place.
In practicallity, this applies only to higher wattage halogens. Below 50
watts or so it isn't a problem because there's just not enough heat to
crystallize the quartz envelope where the oil from your fingers has
"insulated" it from the outside air. Even bulbs of several thousand watts
(the largest are 24,000 watts!) may be simply wiped clean with a paper towel
and alcohol if touched.
Hope this helps.
John
"Truelove"-Westsail 43
Truelove's pic is at <http://users.erols.com/woax/43pix.html> (Thanks Rick!)
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