On Wed, 13 May 1998 05:46:34 -0500 Martin McCormick writes: > I used to hear about something called the halogen cycle when I >worked as a technician with audio visual equipment. The idea was that >a halogen lamp filament gives off vapor when run at reduced brightness >and that the vapor redeposits back on to the filament when it was run >at full brightness. I don't know if this is for real or one of those >bits of urban wisdom that turn out to be either just flat wrong or >based on >out-dated information. No, it's approximately true. Running a halogen bulb at 10-20% less than rated voltage will shorten it's life. The gas in the bulb is a mixture (including halogens) at high pressure. When the temperature is high enough, the "halogen cycle" returns most of the tungsten that comes off the filament back to the filament. The filament is the same as in a regular bulb, but due to the halogen cycle it can be run hotter, thus these bulbs have a brighter, whiter light. At much less than rated voltage, either type of bulb will last a very long time because the filament doesn't get hot enough to "evaporate" in the first place. _____________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com Or call Juno at (800) 654-JUNO [654-5866]