High Efficiency LEDs?

 
My apologies if the following question is a dumb one, but could someone
please explain to me if there is any difference between the standard
LEDs that one might expect to find at Radio Shack and those installed in
certain newer-model, long-lasting LED-style flashlights, garden lights
and lanterns?

I have seen several products in catalogs in recent months which specify
that because of new technology, their LEDs not only last 1000,000 hours,
but that they draw less power than other, older LEDs. Is that the case?
And if so, could someone tell me specifically where I might be able to
purchase them and exactly what I should ask for?

I'm looking for amber-colored LEDs as opposed to the white ones-- if
that makes any difference. I'm hoping to replace the LEDs in my solar
powered lamp posts which currently yield approximately seven hours of
run time on one day's charge. I'm afraid that switching to another brand
of LED would eat up too much power and make the light last fewer hours
during the night.

Please feel free to email me with any information or advice that you
think may be helpful-- it would be greatly appreciated.

Thank you,

Shannon

  Yeah don't bother with white LEDs, they suck the juice. Radioshack also fits
that classification. They tend to get whatever cheap LED they can and throw
it in a standard package and charge $5 for it, and MAYBE the specs are
right. A check a year or so indicated that, for creation of white light,  a
white LED was barely as efficient as a halogen lamp. The main reason they
look so bright is because their light is focused in to a narrow cone. A
white LED is nothing but a blue LED with a phosphor layer to downconvert
that blue in to greens, yellows, reds, etc.. by means of fluorescence to
create the illusion of white light. LED's are VERY good at generating a
monochromatic light (or relatively monochromatic) so their application in
traffic signals, billboards, automobile tail lights, etc.. is quite
efficient, though I believe that the main benefit in traffic lights is that
they last so long (and there are many - so it wouldn't so much burn out as
it would just slowly die)

Yellow LEDS are good - you can get a LOT of brightness out of a good GaInN
(that's Gallium Indium Nitride) unit. That's the new formula that all the
ultrabrights use. Most T 1 3/4 size LEDS draw 30mA. Your whites are GaInN,
and also take anywhere from 20-30mA, though the T1 size may take less, but
the result of simply substituting a smaller size in the circuit might have
unexpected results. GaInN LEDs typically require 3.6 volts. Most of those
little solar landscape lights only have a 1.2V NiMH battery, so some sort of
boost/buck converter or capacitor switching circuit is most certainly
employed to get this increased voltage. That will complicate your efforts to
use a meter to figure out what your current is, as it will be pulsed in some
way.

Amber LEDS are good, just remember, green is where the human visual response
peaks (555 nm wavelength), though green LEDS might look silly in your
application. Also another thing to remember, the mCd rating of the LEDS you
see are based on their apparent brightness.... two identical leds with a
different shaped lens can have two different ratings, but looking directly
at them, the one with the narrow emission profile would appear, and thus be
rated as "brighter"

I'd say you just log on to Allelectronics.com and buy a small assortment of
ultrabright LED's and shine them at a wall and compare for yourself. You
might also be able to buy some kind of a connector or socket that you can
solder in to the lamp units so you can easily swap out any number of
different LED's and compare their performance. Their CB-74 cable might work.
It's spacing is a little wider than a T 1 3/4 LED but they're three for a
buck.

Andy

 Shannon H. wrote:

no, no differance