[rollei_list] Re: OT: Light bulb for slide viewer
- From: Don Williams <dwilli10@xxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 19 Aug 2010 13:36:42 -0500
At 02:57 PM 8/18/2010, Eric Goldstein wrote:
They run the filament at a higher temperature and produce less heat?
Eric Goldstein
When the filament is hotter it produces relatively more useful light
for the power consumed, so it is possible to get the same light
output with less input power. Doing this burns out the filament more
quickly.
This is overcome these days by using the Halogen Cycle, which returns
the evaporated filament material from a gas back to the hot
filament. I used to think that this required a hotter outside
envelope but apparently the Halogen Cycle doesn't depend on that.
Check it out here:
http://en.wikipedia.org/wiki/Halogen_lamp
I think those tiny lamps in the small fancy flashlights use that
style of lamp, but haven't looked to see if they are available with
older style bases.
Those small bulbs, typically 300 and 500 watts, used in standing
floor lamps and the "high intensity" desk lamps use Halogen cycle
bulbs but you will notice that all of them have a glass heat shield
to prevent contact with the basic bulb. In those cases you are
cautioned to not touch the bulb when replacing it because
fingerprints can cause hot spots that damage the bulb.
My notion is to just use a 3 volt bulb with the right base and go
with whatever light level results.
DAW
Other related posts:
