ray@ole.UUCP (Ray Berry) (09/28/88)
Ok- now that blue LEDs are under control again... This past weekend I saw a product that had a very bright red LED lamp in it. The product literature reproduced (evidently) two of the charts from the data sheet- one showing spectral frequency vs relative output (peak @ 650 nm), the other showing luminosity vs. current - which was spec'ed at 3000 millicandellas at 20 ma. forward current. No other data was given. Physically, it was a T-1 package, nothing unusual. Now that is a very high-output LED. Does anyone know who makes such an item? The fellow representing the product said he had to import them- whatever that means. But he would not tell me who made them. Not being a whiz on opto stuff, I hereby submit the matter to the collective con- sciousness of the net. -- Ray Berry KB7HT Seattle Silicon Corp., 3075 112th Ave NE., Bellevue WA 98004 (206) 828 4422 UUCP:...!uw-beaver!tikal!ole!ray =============================================================
skrentny@speedy.cs.wisc.edu (James Skrentny) (09/29/88)
In article <491@ole.UUCP>, ray@ole.UUCP (Ray Berry) writes: > This past weekend I saw a product that had a very bright red LED lamp > in it. The product literature reproduced (evidently) two of the charts > from the data sheet- one showing spectral frequency vs relative output > (peak @ 650 nm), the other showing luminosity vs. current - which was > spec'ed at 3000 millicandellas at 20 ma. forward current. No other data > was given. Physically, it was a T-1 package, nothing unusual. > Now that is a very high-output LED. Does anyone know who makes such > an item? .... One manufacturer of "kilo-bright" LED's is AND, distributed by Newark. Note that the angle of view is much restricted compared to standard LED's. Here are some specs (Newark catalog 109, page 169): red, clear T-1 3/4 package, theta = +/- 4 degrees 1000 mcd @ 20 ma, AND150AR, newark part 87F348, $2.55 ea 2000 mcd @ 20 ma, AND150BR, newark part 87F349, $2.73 ea 3000 mcd @ 20 ma, AND150CR, newark part 87F350, $5.50 ea red, clear T-1 3/4 package, theta = +/- 20 degrees 300 mcd @ 20 ma, AND120AR, newark part 87F351, $2.55 ea 600 mcd @ 20 ma, AND120BR, newark part 87F352, $2.73 ea 900 mcd @ 20 ma, AND120CR, newark part 87F353, $5.50 ea -jim bo -------- Jim Skrentny University of Wisconsin Computer Systems Lab office 608-263-7463 (afternoons), home 608-251-5683 USENET: ...!{allegra,heurikon,ihnp4,seismo,ucbvax}!uwvax!skrentny ARPA INTERNET: skrentny@cs.wisc.edu
strong@tc.fluke.COM (Norm Strong) (09/29/88)
In article <491@ole.UUCP> ray@ole.UUCP (Ray Berry) writes: }Ok- now that blue LEDs are under control again... } This past weekend I saw a product that had a very bright red LED lamp }in it. The product literature reproduced (evidently) two of the charts }from the data sheet- one showing spectral frequency vs relative output }(peak @ 650 nm), the other showing luminosity vs. current - which was }spec'ed at 3000 millicandellas at 20 ma. forward current. No other data }was given. Physically, it was a T-1 package, nothing unusual. } Now that is a very high-output LED. Does anyone know who makes such }an item? The fellow representing the product said he had to import them- }whatever that means. But he would not tell me who made them. Not being }a whiz on opto stuff, I hereby submit the matter to the collective con- }sciousness of the net. I suspect that the units were microcandelas. Product literature people are not that careful, as a usual thing. Why don't you check with the mfgr. -- Norm (strong@tc.fluke.com)
commgrp@silver.bacs.indiana.edu (09/30/88)
In article <491@ole.UUCP>, ray@ole.UUCP (Ray Berry) writes: > This past weekend I saw a product that had a very bright red LED lamp > in it... 3000 millicandellas at 20 ma. forward current. Physically, > it was a T-1 package, nothing unusual. > Now that is a very high-output LED. Does anyone know who makes such > an item? .... I read about "high-brightness" LEDs from Japan in Modern Electronics magazine a couple of years ago. The author said that clusters of them would eventually replace incandescent bulbs for car tail-lights. It was the April issue, so I didn't believe it! :^) The DIGI-KEY catalog has some 2000mcd LEDs for roughly $5. I'm told that these are the same as Radio Sh*ck 276-087 LEDs, which cost less but are presently in short supply; your local RS may be able to special-order them. (These are not to be confused with RS' other "high brightness" LEDs, which are multiple chips in one package.) Some cave-explorer friends are experimenting with the new LEDs for emergency light sources: Two LEDs, each in series with a 33-ohm resistor, connected to two alkaline AA-cells, will make enough light to get out of the cave, for 24 hours. Some cavers have clustered as many as 9 LEDs. -- Frank reid@gold.bacs.indiana.edu
cook@stout.ucar.edu (Forrest Cook) (09/30/88)
In article <491@ole.UUCP> ray@ole.UUCP (Ray Berry) writes: >This past weekend I saw a product that had a very bright red LED lamp in it. .. >Does anyone know who makes such an item? Hewlett Packard makes several extra bright LEDs. They were offering them free in a demo package a few months ago. Check out a back issue of Electronics or Electronic Design. I got a couple and am very impressed. They produce a very bright light at 20 ma current and are also great for low current designs with normal light output. I use one for a tail light on my bicycle! See HP for the specs. F. Cook
cdl@mplvax.nosc.MIL (Carl Lowenstein) (09/30/88)
In article <7200014@silver> commgrp@silver.bacs.indiana.edu writes: >Some cave-explorer friends are experimenting with the new LEDs for >emergency light sources: Two LEDs, each in series with a 33-ohm >resistor, connected to two alkaline AA-cells, will make enough light >to get out of the cave, for 24 hours. >-- >Frank >reid@gold.bacs.indiana.edu Why not connect the two LEDs in series and use a smaller resistor. Don't use the battery energy heating a resistor when you could be using it to make LED light. Answer of sorts to the question above: the forward drop across the LED is too great. About 2 volts for green. Revise the question: How about 3 alkaline cells and 2 LEDs. Should be a better match to the problem, at a 50% weight penalty. -- carl lowenstein marine physical lab u.c. san diego {ihnp4|decvax|ucbvax} !ucsd!mplvax!cdl
langston@repoman.uucp (Kevin Langston) (10/01/88)
In article <7200014@silver> commgrp@silver.bacs.indiana.edu writes: > >I read about "high-brightness" LEDs from Japan in Modern Electronics >magazine a couple of years ago. The author said that clusters of them >would eventually replace incandescent bulbs for car tail-lights. It >was the April issue, so I didn't believe it! :^) [stuff deleted] > >Frank >reid@gold.bacs.indiana.edu Well you can believe it! Next time you're stopped in traffic behind a Nissan 300ZX, take a look at the center mounted tail light. You'll notice that it is a slightly different color than the other tail-lights, a really nice LED kinda red. And they are BRIGHT! Now if they'd only start turning up in the salvage yards.... _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/_/_/ _/_/ From the virtual desk of: Kevin Langston _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ _/_/_/_/ Convex Computer Corporation __/_/_/_/_/_/_/_/_/_/_/_/_/_/_/ _/_/_/_/ 701 North Plano Road
henry@utzoo.uucp (Henry Spencer) (10/02/88)
In article <779@mplvax.nosc.MIL> cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein) writes: >>Some cave-explorer friends are experimenting with the new LEDs for >>emergency light sources: Two LEDs, each in series with a 33-ohm >>resistor, connected to two alkaline AA-cells... > >Why not connect the two LEDs in series and use a smaller resistor. ... >Answer of sorts ... the forward drop across the LED >is too great. About 2 volts for green... In any power-critical application, one would probably want to use red, not green. In all the LED families I'm familiar with, red is streets ahead of green on luminous efficiency. However, this doesn't affect the issue much, since the forward drop in red LEDs is only a little lower than green. -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu
jbm@eos.UUCP (Jeffrey Mulligan) (10/04/88)
From article <1988Oct2.053515.18004@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer): <>>Some cave-explorer friends are experimenting with the new LEDs for <>>emergency light sources: Two LEDs, each in series with a 33-ohm <>>resistor, connected to two alkaline AA-cells... < In any power-critical application, one would probably want to use red, < not green. In all the LED families I'm familiar with, red is streets < ahead of green on luminous efficiency. However, this doesn't affect < the issue much, since the forward drop in red LEDs is only a little < lower than green. For the caving application, you would probably want to compute the luminous efficiency using the scotopic luminosity function (rods instead of cones). This would shift the balance towards green by 1-2 orders of magnitude. -- Jeff Mulligan (jbm@aurora.arc.nasa.gov) NASA/Ames Research Ctr., Mail Stop 239-3, Moffet Field CA, 94035 (415) 694-6290
cdl@mplvax.nosc.MIL (Carl Lowenstein) (10/04/88)
In article <1988Oct2.053515.18004@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >In article <779@mplvax.nosc.MIL> cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein) writes: |>>Some cave-explorer friends are experimenting with the new LEDs for |>>emergency light sources: >In any power-critical application, one would probably want to use red, >not green. One wonders about the tradeoff with the human eye's greater efficiency in the green on the receiving end. -- carl lowenstein marine physical lab u.c. san diego {ihnp4|decvax|ucbvax} !ucsd!mplvax!cdl
henry@utzoo.uucp (Henry Spencer) (10/04/88)
In article <1652@eos.UUCP> jbm@eos.UUCP (Jeffrey Mulligan) writes: > [red vs green LEDs, efficiency etc.] >For the caving application, you would probably want to compute the >luminous efficiency using the scotopic luminosity function (rods >instead of cones). This would shift the balance towards green >by 1-2 orders of magnitude. I'd be somewhat surprised if it were that large, based on some tinkering with LEDs in low light levels... but I agree that this is the right way to answer the question. Better than computing the efficiency, actually, would be to experiment, which would also give you some idea of what the lowest usable light levels would be. -- The meek can have the Earth; | Henry Spencer at U of Toronto Zoology the rest of us have other plans.|uunet!attcan!utzoo!henry henry@zoo.toronto.edu
ray@ole.UUCP (Ray Berry) (10/05/88)
>>emergency light sources: Two LEDs, each in series with a 33-ohm >>resistor, connected to two alkaline AA-cells... > >Why not connect the two LEDs in series and use a smaller resistor. ... >Answer of sorts ... the forward drop across the LED >is too great. About 2 volts for green... I suspect a single-chip switching converter could be configured as an efficient method of powering a couple LEDs - for instance, two lamps in serial driven through a convertor designed to convert 5-9 vdc to a 20 mA. output current. A 9 volt alkaline could then power the lamps efficiently over a wide range of its service life. -- Ray Berry KB7HT Seattle Silicon Corp., 3075 112th Ave NE., Bellevue WA 98004 (206) 828 4422 UUCP:...!uw-beaver!tikal!ole!ray =============================================================
neals@tekigm2.TEK.COM (Neal Sedell) (10/05/88)
Sorry to transpose this response with another article, but our mailer has been extremely brain-damaged for quite a while now. It used to be almost perfect and I felt sorry for those less fortunate... >>Some cave-explorer friends are experimenting with the new LEDs for >>emergency light sources: Two LEDs, each in series with a 33-ohm >>resistor, connected to two alkaline AA-cells, will make enough light >>to get out of the cave, for 24 hours. > >Why not connect the two LEDs in series and use a smaller resistor. Well, since we're talking about an emergency light source, the key-word is RELIABILITY, not efficiency! >Answer of sorts to the question above: the forward drop across the LED >is too great. About 2 volts for green. Revise the question: How >about 3 alkaline cells and 2 LEDs. Should be a better match to the >problem, at a 50% weight penalty. Same here. Who needs another 50% probability of battery failure??? And yes, I'm glad we seem to have the green/red issue resolved... -- Neal Sedell
mbutts@mntgfx.mentor.com (Mike Butts) (10/06/88)
From article <7200014@silver>, by commgrp@silver.bacs.indiana.edu: > > I read about "high-brightness" LEDs from Japan in Modern Electronics > magazine a couple of years ago. The author said that clusters of them > would eventually replace incandescent bulbs for car tail-lights. It > was the April issue, so I didn't believe it! :^) > Next time you're behind a recent Nissan 300ZX sports coupe in traffic, take a good look at the center stop light. It's very wide and thin, and has the LED shade of red, slightly different than the usual automotive taillight red. I'm fairly sure it's an array of LEDs. Perhaps a source of high-brightness LEDs is the parts dept. of your Nissan dealer! (I'm fairly sure it's the 300ZX, in any case it's their big "Japanese T-Bird" model.) -- Mike Butts, Research Engineer KC7IT 503-626-1302 Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton OR 97005 ...!{sequent,tessi,apollo}!mntgfx!mbutts OR mbutts@pdx.MENTOR.COM These are my opinions, & not necessarily those of Mentor Graphics.