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From: jerry@oliveb.UUCP (Jerry Aguirre)
Newsgroups: net.consumers
Subject: Re: long lasting lightbulbs
Message-ID: <255@oliveb.UUCP>
Date: Tue, 22-Jan-85 20:45:39 EST
Article-I.D.: oliveb.255
Posted: Tue Jan 22 20:45:39 1985
Date-Received: Thu, 24-Jan-85 06:40:08 EST
References: <-28400@cadovax.UUCP> <6100001@hpfclv.UUCP>
Organization: Olivetti ATC, Cupertino, Ca
Lines: 42

> Yes,  lights  batterys  and  nylons.  There is a way  around  the  light
> problem  though, you can insert a diode in the line to effectively  half
> wave  rectify  the ac  current.  This will cause the light  bulb to burn
> dimmer  and  thereby  remain  cooler.  Heat,  or  'burning  up',  is the
> downfall of the filement in every light bulb.  To maintain light output,
> you install a higher wattage light bulb which still burns cooler that it
> is  designed  to burn out at.  This will cause most light  bulbs to last
> about 10 times longer than they are spec'ed to (as if I have measured it
> :-).

> Dan (my 4-year old still knocks the lamps over) Schmidt
> Hewlett-Packard
> {ihnp4 | hplabs}hpfcla!dgs

Yes you can make a light bulb run longer by reducing the power to it.
A diode or a higher voltage lamp (220 lamp on 110 voltage) will make
the bulb last a long time.

The problem is that it will cost you in electricity.  The effeciency of
an incandesant lamp is some kind of logrithmic function of the voltage,
decrease the voltage 50% and you can get a 70% decrease in light
output.  You could be using twice the electricity to get the same
amount of light.

Light bulbs are manufactured with total cost in mind.  The cost of the
bulb is probably small compared to the electricity it will consume in
its expected lifetime.

The reduced power approach only makes sense if changing the bulb is
difficult or is little used.  A lamp located at the top of a stairwell
or in an attic might be more trouble to change than the cost of the
extra electricity.

There is an approach that extends life without extra electrical costs.
It uses a varisistor in series with the bulb.  This turns the bulb on
gradually but supplies full power after warm up.  This eases the thermal
stress on the filiment.  Bulb life is more proportional to the number of
times it is turned off and on than burn time.  A bulb on a flasher can
burn out after only a few hours of operation.

				Jerry Aguirre @ Olivetti ATC
{hplabs|fortune|idi|ihnp4|tolerant|allegra|tymix}!oliveb!jerry