Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site brl-tgr.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!harpo!decvax!genrad!panda!talcott!harvard!seismo!brl-tgr!ron From: ron@brl-tgr.ARPA (Ron Natalie) Newsgroups: net.consumers Subject: Re: Lifetime Lightbulbs Message-ID: <8054@brl-tgr.ARPA> Date: Tue, 5-Feb-85 16:33:34 EST Article-I.D.: brl-tgr.8054 Posted: Tue Feb 5 16:33:34 1985 Date-Received: Sat, 9-Feb-85 09:13:52 EST References: <1516@hplabs.UUCP> <517@houxu.UUCP> Organization: Ballistic Research Lab Lines: 13 > I once had a man who knew light bulbs say that > there was a failure mode called "tungten migration". > > The material in the filiment "migrates" in the direction of > the current. This causes diameter reductions in the light bulb > filiment. Which causes higher resistance and heat at that spot. > And the bulb burns out. > Also, the tungsten actually boils off. If we fill the bulbs with a halogen we can get the tungsten deposited back on the filiment. I used to be able to explain how this works, but I've forgotten. -Ron