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From: bobt@pogo.WV.TEK.COM (Bob Tidrick)
Newsgroups: sci.electronics
Subject: Re: incandescent light bulb life extender
Message-ID: <10183@pogo.WV.TEK.COM>
Date: 6 Dec 90 16:50:30 GMT
References: <58335@brunix.UUCP> <1990Dec4.113531.10096@csc.canterbury.ac.nz> <1990Dec4.042524.14018@ux1.cso.uiuc.edu> <30670@boulder.Colorado.EDU>
Reply-To: bobt@pogo.WV.TEK.COM (Bob Tidrick)
Organization: Tektronix, Inc., Wilsonville,  OR.
Lines: 32

In article <30670@boulder.Colorado.EDU> skwu@spot.Colorado.EDU (WU SHI-KUEI) writes:

>while the efficiency (light output) drops almost linearly with reduced voltage,
>building the diode in would only reduce the sale of bulbs.
>
>Incidentally, a good source of long life bulbs is any electrical supply
>house that sell 125volt bulbs at reasonable price.

Another thing that effects bulb life is the thickness of the envelope. I have
three 40W bulbs in my house that  are now over 12 years old. They are in my
bathroom and are made of a very thick glass. One of them has a broken
filiment but when it goes out, which is every couple of months or so, I give
it a bump and it works again. BOY, HOW DID THE BULB MANUFACTURERS LET THIS ONE
SLIP BY.

A thicker envelope will reduce the amount of oxygen that assimilates through
the glass to the filiment. Charging the envelope with an inert gas such as
argon further extends the life of the bulb.

From my experiance light bulbs are engineered to have a limited life.

Another question.  How can they sell Christmas lights for as little as $ 0.10
and a 40 watt bulb sells for nearly $2.00 ? Can it all be Volume? The design
is basicly the same. There is only a few cents more material.  I think we are
getting ripped off two ways here. 

I usually don't get up on soap boxes. Some times they fall apart.
-- 
                                                Bob Tidrick
                                                GPID Engineering
                                                Tektronix Inc.
                                                Wilsonville OR.