1980-1989: LEDS BRIGHTEN OUR LIVES
(Received 03-09-07, tested 03-10-07)
This is a wide-angle deep red LED emitter, which was apparently designed to be used in optical media reading devices before the advent of inexpensive red laser diodes and instead of bulky and power hungry HeNe lasers.
This isn't just any ordinary LED, it comes in a very heavy aluminum slug which appears to be a heatsink. I rather quickly destroyed two of the four test units; one by connecting the wires on my power supply to the wrong terminals and another by turning the voltage too high. I did note that this unit emitted a flash of GREEN just before its destruction. The first one still emits a dull red glow, but the second one is - as they say - "toast".
According to the Ebay seller, if a positive (magnifying) lens is placed in front, they will produce a beam not that unlike that produced by an inexpensive red laser pointer. I don't know where my two positive lenses are right at the moment though, so I cannot try this to see what kind of results I might have.
Here is a photograph of the LED itself.
The Vf in this photograph and for the spectrum below is approximately +3 volts.
Spectrometer plot of this LED.
Ocean Optics USB2000 Spectrometer on loan from WWW.TWO-CUBED.COM.
The peak wavelength appears to be ~730-740nm, which is a very deep cherry red.
Also, note the unusually broad emission band; the spectral line halfwidth appears to exceed 50nm.
This rather ordinary 1980s yellow-green LED is not quite ordinary. An insect (a fungus gnat, a midge, a housefly, or other flying insect in the order Diptera) is embedded in the epoxy encapsulant.
As you can clearly see, a fly of some kind is embedded in the epoxy of this LED.
The pictures on the left shows the LED unlit, the picture on the right shows it lit.
The fly was encapsulated to the side of the LED package, rather than above or on the die cup.
Foreign objects in LEDs are very, very uncommon; this LED should be held onto rather than being disposed of. The fact that it made it on The LED Museum's exhibits is testament to that. :-)
The pictures were sent by a website fan, and used with permission.
This, my friends, is what I considered to be "The Ultimate LED" back in 1981 when I stumbled across it.
Manufactured by Fairchild, this is their very narrow beam, almost laser-like FLV-104, which, as far as I can determine, was mainly
used in "simulated laser" kits sold by Information Unlimited between about 1980 and 1985. The kit consisted of a two-piece telescoping metal tube, a long focal length lens, this LED, and a circuit that fed high current pulses to it. I believe it was meant to be driven with very short pulses of 500mA, but it will POP & DIE if it is fed more than 50-60mA continously.
When the project was assembled correctly though, it was supposed to generate a bright red beam that (at that time) could be used like a low powered visible laser!
Notice how the leadframe (the metal parts inside the LED) is mounted extremely low in the package, and note the odd elongated bullet shape. Both of these together work to provide the extremely narrow, 2° or 3° beam this LED projects.
This LED was generously donated by D. Conrad, who originally purchased five of them in 1985 for a high school laser project.
They were thought to have been purchased from an RCA distributor for a cost of $28.00 for all five - apparently it would have also cost the same $28.00 for just one, so five were bought, paid for by his school. One was immediately sacrificed to The LED Gods by way of a 9v transistor radio battery, one ended up in my museum some sixteen years later, and the whereabouts of the remaining three is unknown.
They were also available from Information Unlimited as a replacement part for their simulated laser kit at a cost of $8.00 apiece. My original (and only) sample was lost - probably blown up out of ignorance - sometime in the early 1980s.
It may also have died by having a lead break off... I'm just not 100% sure what happened to it anymore.
On the test target you can see the unusually narrow beam generated by this LED.
For this picture, the LED was held approximately 3 feet from the target, fed 40mA, and no additional optics were used.
Although this isn't quite the same as my original FLV-104, it is very similar.
Here you can see the LED chip divided by a pair of lines. I didn't know back then (well, I *think* I did but wasn't sure), but these lines are very probably part of the top ohmic contact, and are there to help distribute current to the LED chip more effectively. The depression at the lower right is where the bond wire attaches to the chip; you can faintly see it extending to the lower right of the photo.
My original FLV-104 had a perfect elongated oval with the two lines running through it and a small, crescent-shaped "bite" out of an otherwise rectangular center segment where the bond wire was attached. So apparently, this device went through some revisions before being discontinued.
This sample has a brightness of 66mcd at 35mA - which was pretty amazing in 1981.
Update 03-04-04: Kevin C. supplied the documentation for this LED that I was looking for!!!
What surprised me most was the year: 1973!!! :-O I suppose I could move it to the 1970s section, but as Seven of Nine on Voyager might say, "that would be irrelevant".
The FLV-104 LED is rated to have a continuous forward current of 100mA, and a peak forward current (100 microsecond pulses, 1% duty cycle) of 1,000mA (1 amp)!
The power dissipation of this LED is 200mW (0.2 watts) at 25°C.
The forward voltage drop is 2.0 volts typical, 2.5 volts maximum.
Reverse breakdown voltage is 3.0 volts minimum, 8.0 volts typical. So you really can kill these things by hooking them up backwards to a 9V transistor radio battery. :-O
The beam width as specified in the data sheet is 4°, which is still very narrow, but not the 2°x3° (ovoid shape) I originally estimated it at.
The early 1980s ushered in a new era for LED technology.
Prior to this, it was almost impossible to find an LED that had a brightness of greater
than about 68mcd, and that was considered VERY bright back then.
Then, around 1984, something happened. While looking for a Fairchild FLV-104 (see above) in northern California,
I stumbled across the office of an LED manufacturer and started poking around & asking people. One of the engineers
came out with a small plastic baggie, and said "We don't know where you can find the FLV-104, but you might not
want one anymore when you see THIS". He handed me a baggie with a single LED in it.
Well, as it turned out, "this" was a red LED that had JUST come out, and it was rated to have a brightness of 300mcd - completely unprecedented
back then. About a year later, the ER-300 high-brightness red LED made its way into Radio Shack stores. For about three bucks, you too could have
the brightest LED on the block.
This was one of the first LEDs that could do this: project a highly visible, fairly narrow red beam that could easily be seen across a whole room if it was dark.
The chemistry of this new LED was GaAlAs - gallium aluminum arsenide - and it was the first LED built onto a mostly transparent
substrate which helps greatly with increasing the brightness. The peak wavelength is 660nm (according to the package), which appears as a pure red color.
Here is a package with an ER-300 LED in it, as Radio Shack sold them in the middle 1980s.
This package is marked as 99 cents, so it probably came a couple of years or so after the ER-300 first came out.
The back of the package reads, in part:
The ER-300 represents a true breakthrough in brightness levels
achieved by using Gallium Aluminum Arsenide LED technology.
It is many times brighter than ordinary LEDs, yet still runs cool.
Don Klipstein sent the original specimen of an ER-300 LED in mid-1999 along with several other 1980s and 1990s LEDs, such as Radio Shack's version of the TLR-147; a funny red LED with a Fresnel lens top, the ubitiquous XC556R diffused red LED (billions of these must have been made over the years!), and some mid 1990s Toshiba products. The ER-300 LED in its original package was sent by David K. in Oregon in early 2004; and it'll stay in its package unless my original ER-300 fails to show up.
* 1960 * 1970 * 1980 * 1990 * 2000 *
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