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High Efficiency LEDs?

S

Shannon H.

Jan 1, 1970
0
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
 
D

Don Klipstein

Jan 1, 1970
0
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?

Radio Shack has a white one that is definitely fairly high efficiency -
the 276-320. It has a wide beam, unlike the narrow beam of ones used in
flashlights. The one most used in flashlights is Nichia's NSPW-500BS.
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,

Most white LEDs at full power fade with a "halflife" of usually 20,000
to 50,000 hours. I have even sometimes heard 6,000 hours and some junkers
do less than that!
They last longer at reduced power. Most LEDs other than white, pink,
purple, violet and UV last 100,000 hours if not overpowered or overheated.
but that they draw less power than other, older LEDs. Is that the case?

New and old LEDs, and high eff. and low eff. LEDs have similar
current/power input (among those with similar case styles). The highest
efficiency ones of recent years can produce 25-50 (maybe more) times as
much light as those that were the standard in the mid 1970's.
And if so, could someone tell me specifically where I might be able to
purchase them and exactly what I should ask for?

Radio Shack 276-320 is a good white LED for experimenters needing only
one or two and not needing a narrow beam.

For more, have a look at:

http://www.nichia.com - go to "products" - they also have an online
ordering system that can deal with fairly small quantities.

http://www.hosfelt.com - look at their LED page, then give them a call if
you want to place an order.

http://www.misty.com/~don/led.html - my bright and efficient LED page -

I am not a supplier but I mention some good ones.
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.

Amber ones have a lower voltage drop than white ones, tend to have
similar efficiency, and tend to have less "dark condition illumination
power" than white, green and blue due to being less favorable to night
vision. (Orange and red are even worse than amber for stimulating night
vision.)

Also note that amber, orange, red and yellow-green have a voltage drop
about 60% of that of white, blue and non-yellowish green. You may have to
rework things if using amber LEDs in an application that works with white
ones. Amber LEDs have a typical voltage drop of 2.1 volts while white
ones have a typical voltage drop of 3.5 volts.
If you replace white LEDs with amber ones with no other rework, expect
runtime of even less than with white LEDs. You may also have excessive
current through the LEDs.

- Don Klipstein ([email protected])
 
D

David L. Jones

Jan 1, 1970
0
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

Yes, the efficency of LEDs varies greatly.
The newer "high efficency" LEDs use more exotic materials and new
manufacturing processes etc to get greater efficency, i.e. light
output vs current.
To make any decent comparisons you will need the datasheet for the LED
you are using now, or at least the datasheets for the various ones you
plan on buying so that you can make comparisons.
Note however that there is a HUGE amount of variability in the specs
for LEDs. The output intensity in mCd or Lumens, viewing angle etc.
It's ain't easy to just compare LEDs on their mCd rating for instance,
but it's a starting point.

A place to start might be here:
http://www.superbrightleds.com

Regards,
Dave :)
 
L

Le Chaud Lapin

Jan 1, 1970
0
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 cannot attest to the long life, but as far as power goes, I am
definitely convinced there is a big improvement over standard LEDs. I
have a bright white LED flashlight that I bought with a mountain bike
two and a half years ago, and I have been using it as a flashlight for
night jogging regularly with no perceivable degration in power output
on 2 Duracell AA batteries! Every now and then I will run into a deer
(or black bull), which, at 11:00 P.M, is just as startling to me as it
is to the animal, at which point I check it to be sure, and I am
always impressed.

-Chaud Lapin-
 
R

Roger Hamlett

Jan 1, 1970
0
Le Chaud Lapin said:
[email protected] (Shannon H.) wrote in message

I cannot attest to the long life, but as far as power goes, I am
definitely convinced there is a big improvement over standard LEDs. I
have a bright white LED flashlight that I bought with a mountain bike
two and a half years ago, and I have been using it as a flashlight for
night jogging regularly with no perceivable degration in power output
on 2 Duracell AA batteries! Every now and then I will run into a deer
(or black bull), which, at 11:00 P.M, is just as startling to me as it
is to the animal, at which point I check it to be sure, and I am
always impressed.
Look at:
http://www.pressbox.co.uk/Detailed/4882.html
In this case, the life extension, is not in the LED itself, but in changes
to the encapsulating plastic, to stop it darkening, and reducing the
light.
In the UK, the place to go, is:
http://www.ultraleds.co.uk/
Who do everythin from single LED's, to complete assemblies and lamps.

Best Wishes
 
D

Don

Jan 1, 1970
0
If you want a really bright led look up "Luxeon Star LED"

These are the brightest of them all.
 
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