[Physltest] [Phys-L] Re: LED mini-flashlight price break

["Frohne, Vickie" <VFrohne@BEN.EDU>]

The State of Indiana converted all their traffic lights to LED's eith=
er last year or the year before. Turns out that the price of converti=
ng is less than the annual cost of just the electricity needed to pow=
er the traditional incandescent traffic lights, not to mention the ma=
intainence of changing bulbs in traditional lights. Automobile tail l=
ights are also moving toward LED's, in part because of their long-ter=
m reliability.  Several lighting manufacturers are trying to develop =
LED equivalents for the standard household light bulb and the standar=
d office fluorescent light fixture.  The motivation for doing so is h=
igh.  In large buildings, the power costs of operating the lights is =
high (there are LOTS of lights), and the heat from the fluourescent l=
ights is a large fraction of the building's air-conditioning load.  F=
urthermore, there are considerable maintainence costs involved with c=
onstantly changing light bulbs and ballasts, and hazardous waste and =
environmental issues connected with the mercury in fluorescent bulbs.=
  LED's have the potential to be far superior in many ways.  - =20
=20
Vickie Frohne

________________________________

=46rom: Forum for Physics Educators on behalf of Bernard Cleyet
Sent: Thu 1/27/2005 9:11 AM
To: PHYS-L@LISTS.NAU.EDU
Subject: Re: LED mini-flashlight price break



Out here in the boondocks we've had LED traffic signals for a coupala
years; the switch appeared to take only a week.  High end autos have =
had
them for a coupala years too.

bc

Jack Uretsky wrote:

> Hi all-
>        This seems to be the new technology in high-intensity LED's.=
  They
> are beginning to appear as traffic lights, and heaven knows what els=
e.
> Google gave me thousand of hits on something like "LED stage lightin=
g".
>                                        Regards,
>                                                Jack
>
>
>
> On Wed, 26 Jan 2005, John Denker wrote:
>
>
>
> > Next to the checkout stand at Walgreens they are selling
> > little LED flashlights for $1.00 apiece.  Your choice of
> >  -- red
> >  -- green
> >  -- blue
> >  -- white
> >
> > I remember when they sold for many times that price.
> >
> > These are *not* lasers ... they are not collimated and
> > they are not monochromatic.  But the colors look reasonably
> > intense.
> >
> > They're remarkably bright for their size (2cm*2cm*.5cm),
> > the "bulb" will never burn out, and battery life is very
> > good.
> >
> > They're great fun to play with.  You can arrange three
> > primary colors in a circle, pointing inward, and make
> > little Venn diagram with white in the center.
> >
> > Also remember, if you don't have a nice diffraction
> > grating handy, a CD (especially a blank CD-R) will do
> > the job after a fashion.  (DVDs don't work.)
>
> --
> "Trust me.  I have a lot of experience at this."
>                General Custer's unremembered message to his men,
>                just before leading them into the Little Big Horn Va=
lley
>
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