"Old School"

L.E.D.

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Nowadays us lightfreaks enjoy LED's with insane brightness and decent efficiency. Back in the days when there were only old-school dim inidicator LED's, did anybody ever look at one of those and imagine the same semiconductor technology evolved into what we have today? I can tell you back in 1996, I had shoved a red LED into an AA minimag and thought, "darn, this thing is so dim, I wish they will create a high brightness WHITE LED sometime in the future!" When was YOUR first glimpse of this technology? Imagine also what we will have in the future, with HID'ish efficiencies for LED's seemingly looming on the horizon (around 120 lumens per watt).
 

Doug Owen

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L.E.D. said:
Back in the days when there were only old-school dim inidicator LED's, did anybody ever look at one of those and imagine the same semiconductor technology evolved into what we have today?

Guilty.

In the mid seventies I built my first front panel using the then new red LEDs. I was fascinated. A 'bulb' you could dim down.... I saw an immediate use as a meter light (the bulbs we used were a PITA to change...). I got another LED from stock and made a small flashlight with two AAA cells, a small microswitch, a fixed resistor and a trimpot (almost always up to 'full blast' of course). I even used it to light the dark odometer window in my truck at night for a whlie.

lota years back fer sure.

Doug Owen
 

BentHeadTX

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Back in '99 I picked up a greenish/yellowish LED flasher for the front of my bicycle. I wished they made white LEDs with enough power to see things and not just to be seen. In 2001, I picked up a Pelican L1 with a Nichia white LED and wanted more... then the Luxeon BB500 minimag mod hit in late 2002 and I saw the future.
 

Lit Up

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L.E.D. said:
Imagine also what we will have in the future, with HID'ish efficiencies for LED's seemingly looming on the horizon (around 120 lumens per watt).

That's why I'm not really pouring alot of cash into them right now.
Although I still need to get a smallish Lux for EDC.
 

Sleestak

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My father was in the Navy, and was good friends with the director of a NARF facility.

I cannot tell you the very neat things he used to bring home from the shop, things that would probably cost thousands of dollard but that they were simply going to throw away because they were out of spec, didn't work any more, etc. No refurb for most stuff; just toss.



They knew what a voracious appetite I had for dismantling electronics, and so they always brought me things to hammer on. I scarfed a lot of LED's out of the panels and used to play with them. They were weak, but they were very fun to play around with.



For me, it wasn't just cool because it was an led, it was cool because it was an LED from a battle damaged plane back from vietnam. I knew that these electronic parts had flown in combat, and that they had been damaged in combat. Most of the damaged panels were sniped by the NARF crews for show and tell, but bullet holes weren't what I wanted, it was lights.



At one point, I had several Corsair (A-7? the 'wide mouth' jet) and Skyhawk full panels that could be fully lit. I had hooked everything up ghetto style behind them. Some of the panels used LED's primarily, some used a mix of incan and LED, and some still used all incan. I 'saw the smoke' many, many times, but I eventually learned how to keep them alive and well without frying them.



Would have probably been worth a bajillion dollars today if I had kept the stuff, or, knowing how our government works today, they would have come and taken everything back so that they could throw it away.



I would have never dreamed LED's could have gotten so powerful. My first memories were the cheezy orange indicator led's that never seem to die but instead start to flicker for about 20 years instead.
 

jtr1962

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Back about 10 or 12 years ago I had imagined that one day LEDs would actually be useful for more than indicator lights, but I thought that day might be decades in the future. Now for years I had used LEDs as indicators in electronic projects. I did notice that the newest ones were much brighter than the ones from years past. Sunlight viewable was a big thing back then.

Anyway, with that thought in mind, I set about making my first LED application where the LEDs would actually light something up. This was HO train passenger car lighting. I had some yellow-green LEDs which were used for taximeter backlights. By today's standards they were very dim, about 10 mcd, although with a wide 100° or so viewing angle. They probably put out at best 1/10 of a lumen (didn't know how to do the calculations back then). I made a circuit to charge a small NiCad battery which powered the LEDs when the train was stopped or moving slowly. At normal voltages track power charged the battery and lit the LEDs. The actual lighting level was rather dim, even using 7 LEDs driven at 15 mA. Sure, it was noticeably lit in a dark room, but that was about it. As for color, well, that left something to be desired. In truth the yellow-green color was an attempt to imitate fluorescent lighting, but it was even greener than the crappiest cool white tubes imagineable. I lit a few cars and decided that the results didn't justify upgrading my entire fleet. In case anyone is wondering about why I did this at all instead of using incandescents, the reasons were many. Incandescents in models create too much heat, are difficult to change when they burn out, don't give much light for the power (the grain of wheat bulbs probably don't do much better than a few lumens per watt), and only give one kind of light (crappy yellow-orange). I had given up long ago using them to light trains. The less than satisfactory results and maintenance gave me a bad headache.

After my feeble attempt at lighting trains I did use LEDs for one other lighting project. I lit the interior of my thermoelectric temperature chamber with 40 surface mount yellow-green LEDs. Power consumption was nearly 2 watts and light output was lousy at best. Still, it was better than nothing. I remember at the time wishing that LEDs were brighter, and also that they came in white similar to fluorescent lights. Of course, I had no idea how someone would actually make a white LED since LEDs are by definition narrow-band emitters, but I could still wish for one, couldn't I?

I shelved my LED lighting projects and pretty much forgot about LEDs as anything other than indicators until the late 1990s. I remember by then that blue LEDs had finally come down in price from $30 each a few years earlier to about $3. I purchased a few to play with. Interesting but very dim. A year later I purchased my first white LED. Again, interesting, and actually about as bright as a grain-of-wheat bulb. Nice bluish-white color, too. I thought of course of the train lighting project again but at $3.50 a pop and requiring about 5 or 6 per coach it would just be beyond my means. I figured within a few years like everything else electronic mass production would bring down the price. Over the next few years I purchased a few more white and blue LED samples, but the prices were just too high to do anything useful with them.

This brings me to mid 2003. My brother had asked me to find some white and red LEDs for lighting die-cast cars. I was all set to order some whites from an online store at $1.09 each in 100s (a good price I thought) and on a whim decided to check eBay. I was surprised to discover LEDs of similar brightness going for 1/3 that price. I took a chance and ordered some. I tried a few vendors and was fairly happy with the price and brightness. Finally, I could get white LEDs in mass quantities without breaking my budget! I never would have dreamed of this only a few years back. And I could get the other colors as well, all very bright compared to what I was used to. I immediately made an LED bikelight, redid the lighting in my temperature chamber, tested the new lights in my trains. I combed the Internet for LED-related information. I learned of the planned advances for LED lighting in the decades ahead. I was surprised LEDs had progressed this much in so short a time. Later in 2003 I bought a few Luxeons to play with. Amazing I thought, and although still pricey at $10 each I said these will be great once they come down to $3 or so (guess what-that's what they cost now!).

My reawakening to LEDs in mid-2003 wasn't without drawbacks. I noticed another problem. LED brightness was increasing, seemingly overnight. Today's hottest LEDs were yesterday's old news. 8000 mcd was great in mid-2003. A year later 16000 mcd was tops. I decided to not bother stocking up on LEDs, but would rather just get 100 every now and then for evaluation purposes. I also shelved the train lighting project again for two reasons. First of all, although LEDs made huge leaps and the whites were great, I suddenly became much pickier. Remember that 12 years ago I had actually considered sickly yellow-green acceptable. Now I was not only looking for white, but I was aiming to match the 4100K to 5000K tubes commonly used as closely as possible. Most of the available white LEDs were just too blue. At first I mixed white and amber. That did the trick but I figured why not just wait until I could find an LED with better color? Late last year I tested BestHongKong's UWLC whites. Bingo! This was what I was after.

That brings me to the second problem. I didn't want to light my fleet with LEDs only to have ones two or three times as efficient come out in a few years. For even lighting I needed four LEDs per car. I could get satisfactory light from the ~14000mcd UWLC series driving them at about 10 mA (in series via a step-up converter). However, in a few years I might be able to get the same light driving at only 2 or 3 mA. Besides longer life, the lower power requirements made it easier to power the LEDs during times of low or zero track voltage. If I could get the power requirements down enough, then instead of a small NiCad battery I could just use a supercap. Also, supercaps would undoubtably increase in capacity over the next few years anyway, giving me all the more reason to play the waiting game. Anyway, that's where LEDs have brought me on this project to date. I don't want to commit to relighting the fleet until LED efficiency starts to level off. So far this shows no signs of happening for at least another few years. My best guess is that once cheap eBay LEDs are at 150 lm/W there's not much point in waiting.

The moral of this long story? Don't wish too hard for something. You just may get it. Today's LED brightness and prices are something I couldn't have dreamed of only a few short years ago. However, with these advances have come even higher expectations for the future. It's hard to start a project when you just know parts twice as good are practically around the corner.

What's the next big thing? After nearly 50 years with little efficiency advances thermoelectrics seem poised to follow the same curve LEDs are. I recently read about some new thermoelectric materials 2 or 3 times better than the long used Bismuth Telluride. Once these make it out of the lab watch out. The days of compressor-based cooling will be numbered just as the days of the incancdescent light are now drawing to a close.
 

Lit Up

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jtr1962 said:
What's the next big thing? After nearly 50 years with little efficiency advances thermoelectrics seem poised to follow the same curve LEDs are. I recently read about some new thermoelectric materials 2 or 3 times better than the long used Bismuth Telluride. Once these make it out of the lab watch out. The days of compressor-based cooling will be numbered just as the days of the incancdescent light are now drawing to a close.

I'm one of those types that is always looking for any article or snippet I can find on developing technology. I was reading awhile back about a "fuel cell" type of battery that was being toyed around with. It's the same size but half the length of a AA battery and it was powering a laptop for 8-10 hours.

I can only imagine what kind of runtimes an LED flashlight would get on one those. :rock: Not to mention form factors.

They also talked about a "powerstation" for the home being the size of 2 soda cans and independant of the grid. But that would be bad for flashaholics.:laughing:
 

L.E.D.

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WOW. VERY interesting reads! I sure wish I had some interesting stories as those, but all I have to offer is my lame little redled minimag from 96. Anyways, thanks all, keep 'em coming.
 

Nubo

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First LED I saw was in an electronic calculator when they finally dropped below $100 back in the early 70's. I marvelled at the light with no apparent heat. A couple of years later a friend of mine started making novelty gifts by encasing blinking LED circuits with batteries inside clear blocks of plastic. He figured they'd keep on blinking for 3 or 4 years -- mind boggling!! Some years later I made a photo-cell sensor "alarm clock" from some Radio Shack schematic. I threw in the tiniest LED I could find (they had yellow by then), and gave it about 20 microamps. Just enough to be able to see in the dark that the clock was "armed". I loved the idea of that clock since it woke you up later on cloudy days :D

My first white LED light was a give-away keychain light at a consumer electronics show that ran off 3 hearing aid batteries. It was a cool little light. One night I was using it to read and it suddenly got very bright. Then it got very dim... :(

I guess the biggest draw for me has always been the promise of extraordinary efficiency. Something that unfortunately hasn't quite yet been realized for high-power LEDs though it seems to be getting there. The LED lights I have are Black Diamond Moonlight headlamp and an Eternalite. I love that they will run for so many hours on a set of batteries. I will love it if the high-power lights can get the efficiency up and heat down and not have the lamps degrade over time. I'd love to have something solid-state and with longer runtime to replace my HID bike light with but right now the LEDs dont seem to have quite the edge yet. I'm sure they are not far off and also sure that some would argue they are already there.
 

jtr1962

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Nubo said:
...(they had yellow by then)...
That reminds me how excited I was when they finally came out with yellow, then orange, and finally green (actually yellow-green) LED displays. I could finally design projects with something other than boring red 7-segment displays. As of late blue 7-segment displays are starting to become affordable, and I've even seen white.

I'd love to have something solid-state and with longer runtime to replace my HID bike light with but right now the LEDs dont seem to have quite the edge yet. I'm sure they are not far off and also sure that some would argue they are already there.
Actually, at this point the better 5mm LEDs are approaching HID efficiency but at very low drive currents. For example, the BestHongKong 40,000 mcd managed 97 lm/W at 5 mA, although of course they only put out about 1.5 lumens at that drive level, meaning you would need a few hundred to equal the output from even a 5 watt HID.

Cree is supposed to reach 100 lm/W with their power LEDs next year. That may well obsolete the smaller sizes of HID.
 

tvodrd

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Does anybody remember what year the Panasonic 15deg, 1500mcd blues first appeared on the rear cover of Digi-Key's catalog? I think I recall paying ~$6.50 each for the buggers. I gave away a bunch of them epoxied to a 1/2AA cell holder with a micro toggle switch and using a Tadiran 3.6V cell. I still have a 9V snap-on light I made with 14 LEDs, 7 resistors, a tiny toggle for off/on and a 3pos DIP switch which allows selecting either 2/4/6/8/10/12/14 of them to be on. The 9V alky sags so badly that appearant brightness doesn't increase much above about 6. :green:

Larry
 

PhotonWrangler

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I remember that, Larry. I ordered a couple of them also. I immediately saw the possibility of full-color LED-based videoscreens now that they could produce blue.

The first LED that I ran across was one of those diffused red ones with the black base sometime in the early 70s. I bought a couple of them at the local electronics surplus store and I was fascinated by them. I wished those LEDs could've had a water-clear base so I could've seen the chip as it was illuminated.

It occurred to me that I was essentially seeing the direct result of electron flow rather than a "secondary" light source (i.e. light from a heated filament) and I thought and still think that it's the coolest thing.
:)
 

jtr1962

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tvodrd said:
Does anybody remember what year the Panasonic 15deg, 1500mcd blues first appeared on the rear cover of Digi-Key's catalog? I think I recall paying ~$6.50 each for the buggers.
I'd say 1999 or 2000. I remember that's when blue LEDs started to become cheaper and more common. Prior to that, Digikey had offered blue Cree silicon carbide LEDs at $30 each. These were only about 10 or 20 mcd if I recall. It wasn't until maybe 2003 that blue LEDs finally hit mass market prices. Now I can pick up all I want on eBay for $0.10 to $0.20 each.
 

EricB

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I first briefly thought of LED's being used as digital signs for subway cars, except that they only came in single colors red or green. Then, sometime in the 80's I saw one sold in Radio Shack that could change colors, but only red, yellow, green. (I wondered why only those three colors). I hoped they wopuld someday expand to the rest of the colors. But my interest in them really sparked off when I began seeing the large signs made with the RyG's. Then, realizing blue was what was missing, I began follwing closely the development of LED's through the 90's, until they finally came out in Radio Shack in 1997, and then made their first appearances on early DVD players the following year, along with the Bud sign in Times Sq (the first SRGB sign to go up there, and is still there). Afterwards, LED's took off all over the place.
However, the subways, in which I first envisioned full color LED sign, are finally adopting the signs for the route--but only in the single color red I had first imagined!

I could finally design projects with something other than boring red 7-segment displays. As of late blue 7-segment displays are starting to become affordable, and I've even seen white.
I wonder if they will ever have RGB 7-segment dispalys.
 

tvodrd

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" I wonder if they will ever have RGB 7-segment displays." There are currently industrial process meters you can set to go from green to red display values when the parameters they are monitoring are out of their "window." Newport Electronics, for one offers them. I haven't seen RGB yet. I had a blue 7-seg readout I cobbed together ~'92-3 on a digital thermometer displaying water block temp on the computer I recently retired. :D

Larry
 

jclarksnakes

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...Almost 20 years ago I had a Minimag and put an LED I got at Rafio Shack in it. I think the LED was IR but I am not sure. It was VERY dim. I used it as my cockpit light when flying with night vision goggles. A couple years later I realized that I had never changed the batteries and it was still running strong. This was pretty amazing as the incandescent bulb in a Minimag would run down the AA batteries of that day real quick. We began using LED fingerlights and lip lights powered by single watch and hearing aid batteries for goggle flying in the late 80s. It did occur to me that LEDs were extremely efficient but not that they would ever be bright. I would not have dreamed that LEDs would ever make enough light to be used in a flashlight for anything other than providing very very low light levels. I had had LEDs in handheld calculators in the early 70s and there had been no big advance in LED light output that I knew about from the 70s to the 80s. The only sign of progress was that LEDs and LED equipped calculators had dropped a whole lot in price. I did not become afflicted with flashaholism until a few months ago and I was amazed to learn that LED flashlights were so bright.
...BTW, we also used Cyalume lightsticks for night vision goggle flying. The regular ones worked great for marking LZs. We also had IR ones that we would use when walking around with helmet and goggles on and they would provide just the right amount of light to make NVGs light up nice.
jc
CW4, USA (retired)
 
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