Because LED flashlights have gotten so popular, (and there are even
several websites that show you how to convert existing flashlights to
use LEDs by installing an LED and a resistor into a old incandescent
bulb base), there must be commercially made LED bulbs that simply
screw into existing bulb sockets, aren't there? I mean, it would only
seem logical.
I presently have an "itty-bitty booklight" whose incandescent bulb is
rated "4.8V 0.5A" which burns out after only about 15 hours of use. At
$3.00 each, that's rather expensive, and I'd like very much to replace
that bulb with an LED bulb.
So rather than having to build one myself from parts, is there a place
that sells them ready-made (preferably a retail store in New York City
but mail-order is OK too)?
The best white LEDs are only a little more efficient than incandescents,
and the most efficient laboratory prototype white LEDs that I have heard
of so far have efficiency about that of better compact fluorescents.
Please note that incandescent lamps have significant economies of scale.
Lower wattage ones have thinner filaments that must be operated at a less
favorable lower temperature for the same life expectancy, or must have
life expectancy compromised to achieve the same efficiency as higher
wattage incandescent lamps. A 1-watt flashlight bulb rated to last 15
hours has efficiency similar to that of a 100 watt lightbulb rated to last
750 hours. 1-watt incandescents with life expectancy 750 hours or more
have efficiency much less than the 16.9-17.5 lumens/watt of 100 watt 120V
incandescents rated to last 100 hours.
Really good white LEDs in current production achieve 20-30 lumens per
watt, and even that can be a little optimistic. I have heard that a top
rank of an especially efficient model by the manufacturer best known for
making the most efficient ones in recent production over the past year or
two may achieve or slightly exceed 40 lumens/watt, but this is not their
usual current production of that model.
Screw-in "medium base" LED "bulbs" are available from:
LEDTronics (
http://www.ledtronics.com)
ETG Technology (
http://www.etgtech.com) - with possible minimum orders of
size suitable for direct order from a manufacturer's sales office
Bivar,
http://www.bivar.com - theirs may be the ETG ones, and smaller
orders may have to go through their distributors of theirs such as Future
Electronics (
http://www.futureelectronmics.com), and distributors may
impose minimum orders and may make you wait for them to order stock.
Please check pricing of small quantities through distributors before
pestering the manufacturers.
Expect prices to be high enough to make white LED "bulbs" uneconomical
for general lighting. The news is not as bad for colored ones, since
there are red, orange, yellow, green and bluish green LEDs with efficiency
like that or exceeding that of white LEDs. Although blue LEDs are less
efficient than white ones, it is easy to find ones with efficiency much
more than that of blue-filtered incandescent lamps.
For example, LEDs do achieve major energy savings over incandescents in
traffic lights. (Traffic light bulbs generally have to last 8,000 hours
or maybe sometimes more, and have efficiency around 11-13 lumens per watt
- and the red and green "lenses" only let through something like 30% of
the light, resulting in an overall efficiency of somewhere around 4 lumens
per watt, maybe only around 3 lumens per watt.)
I mention more in:
http://www.misty.com/~don/lede.html - where and why LEDs achieve
efficiency much more than that of incandescents, and why not for general
room lighting
http://www.misty.com/~don/led.html - some bright/efficient LED models
http://www.misty.com/~don/ledx.html - my LED "top page"
http://www.misty.com/~don/light.html - my "lighting technology top page"
- Don Klipstein (
[email protected],
http://www.misty.com/~don/index.html)