This is PAGE 3 of the 1970s exhibit. Go here to return to PAGE 1.




1970-1979: THE LED COMES OF AGE

Unknown-type red LED
Received ??-??-??, tested 03-27-08
This is a diffused red LED that I obtained probably sometime within the last five years - it turned up in a small plastic box while I was looking for another product that required spectroscopy (pronounced "") on the early-afternoon of 03-24-08.


This is the LED itself; note the gold plated leads (which appear to have standard spacing for 5mm LEDs) and the black plastic ring moulded into its base.


Spectrographic analysis of this LED, when driven at 24.76mA.
USB2000 spectrometer graciously donated by P.L.




Stanley # FR500 Red LED
Received 09-06-07, tested 09-11-07

A fan of the website (F.G. of Rolling Meadows IL.) sent eight of these LEDs, plus a whole box bountifilly overflowing with other LEDs & photonic goodies. This is a red LED in a water-clear, colorless epoxy body. It resembles most modern 5mm LEDs in clear cases.


Spectrographic analysis of this LED, when driven at 19.28mA.
USB2000 spectrometer graciously donated by P.L.




AC Interface Inc. (Stanley?) # RU63015 Double-Die Red LED
Received 09-06-07, tested 09-07-07

A fan of the website (F.G. of Rolling Meadows IL.) sent eight of these LEDs, plus a whole box bountifilly overflowing with other LEDs & photonic goodies. It comes in a white colored body with a transparent, water-clear lens on the end.


Here's a photograph of the LED itself.


And here's a photograph where I attempt to show the two dice inside.
The LED was driven at ~1.9mA for this photograph.
One of the dice really does appear significantly brighter than the other; just by "eyeballing" it, I'd venture to say it has different chemistry than the other as well.


Spectrographic analysis of this LED, when driven at 19.28mA.
USB2000 spectrometer graciously donated by P.L.




(Suspected) Fairchild # FLV-117 5mm (T1 3/4) Diffused Lens Red LED
Received 07-14-07, tested 07-15-07

A fan of the website sent five of these LEDs. It comes in a red colored diffused epoxy body, and is of standard 5mm (T1 3/4) size.


Here is a photograph of the LED itself, showing the bottom.

The color appears to be a slightly deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
USB2000 spectrometer graciously donated by P.L.




Unknown-Type Red LED
Received 09-26-06, tested 10-01-06

A fan of the website sent this LED along with several others. It comes in a red colored slightly diffused epoxy body, is very small (perhaps T1/2), and it has axial leads, not radial ones.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a slightly deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Unknown-Type Red LED
Received 09-26-06, tested 09-30-06

A fan of the website sent this LED along with several others. It comes in a red colored transparent epoxy body, and although it has a domed lens, the internal parts are near the top of the package so it has a wide viewing angle.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a slightly deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Unknown-Type Red LED
Received 09-26-06, tested 09-30-06

A fan of the website sent this LED along with several others. It comes in a red diffused 5mm (diameter) elongated epoxy body.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Unknown-Type Red LED
Received 09-26-06, tested 09-30-06

A fan of the website sent this LED along with several others. It comes in a water-clear 5mm epoxy body, and has a relatively flat lens, so it has a wide viewing angle.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a slightly deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Unknown-Type Single-Lead Red LED
Received 09-26-06, tested 09-28-06

A fan of the website sent this LED along with several others. It comes in a rather unusual pin-shaped package, with its cathode (-) lead extending down from its body, and its anode (+) connection being the metal body of the LED itself.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED.
Plot does not reach the top of the chart because the intensity is too low.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Unknown-Type Red LED
Received 09-26-06, tested 09-27-06

A fan of the website sent this LED along with several others. It comes in a water-clear 5mm epoxy body, and has gold plated leads.


Photograph of the LED itself; this lamp is way too low in intensity to furnish a beam photograph or an intensity measurement.

The color appears to be a deep red, which does not visibly shift in wavelength as drive current is varied.


Spectrographic analysis of this LED, when driven at just under 30mA.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Western Electric Red LED
Received 02-08-06, tested 02-19-06, analysed spectrographically on 10-16-09.

A fan of the website sent this LED which he identified as having been used in Western Electric telephone equipment in the 1970s.
This LED glows red, and has a wide viewing angle of approximately 100°.

It is smaller than a 5mm (T1 3/4) LED but larger than a 3mm (T1) LED.


Left (or top): The LED by itself.
Right (or bottom): The LED giving off its pleasant red glow in the test set.

Intensity is too low to be measurable with the instruments at my disposal. I'm uncertain as to what the operating chemistry is; there was no noticeable color shifting between If=2mA and If=75mA. There was no real difference in intensity for that matter. This LED would be perfectly happy with a drive current of 10mA.



Spectrographic analysis of this LED.



Spectrographic analysis of this LED; spectrometer deliberately "overloaded" to show yellow-green emission.



Archer, # 276-026 "LIGHT EMITTING DIODE"
Received 07-23-05, tested 08-02-05, spectroscopy performed 12-06-09

A fan of the website sent a box containing a number of vintage LEDs; the enclosed note expressed his hope that at least some of them would show up on this website. And I can say, with absolute, positive, 100% certainty that many of them will.

This is a diffused, nonstandard size, red LED that Archer (now known as Radio Shack) sold in its stores sometime in the 1970s.
The writing on the included spec sheet indicates it was intended to have an operating current of 20mA with a maximum of 50mA, and a luminous intensity of 0.3mcd at 20mA. As I just said, it comes with a specifications sheet, showing its operational characteristics and several graphics that show things such as its spectrum, current and brightness, voltage and current consumption, etc.

According to the spec sheet, this LED has a peak emission of 650nm, and a spectral line halfwidth of 25nm.

The body style appears virtually identical to the Fairchild FLV-102, a red LED in a diffused case. An example of one appears farther down this very web page. The inscription on the bottom of this LED's body reads "NSL102 317".
So it does indeed appear to be a Fairchild Electronics product.

The flat spot on the bottom of the LED's body is next to the (+) lead.

Left: Package this LED came in.
Right: The LED itself in the test set.



Spectrographic analysis of this LED.
USB2000 spectrometer graciously donated by P.L.



Archer, # 276-040 "LIGHT EMITTING DIODE"
Received 07-23-05, tested 07-26-05

This is a diffused, nonstandard size, red LED that Archer (now known as Radio Shack) sold in its stores sometime in the 1970s.
The writing on the back of the package indicates it was intended to have an operating current of 20mA with a maximum of 40mA. No luminosity value is furnished.

The body style appears virtually identical to the Fairchild FLV-102, a red LED in a diffused case. An example of one appears farther down this very web page. The only readily visible difference between the two is that this LED has a colorless frosted lens, and the FLV-102 has a red-tinted frosted lens.

The flat spot on the bottom of the LED's body is next to the (+) lead.

Left: Package this LED came in.
Right: The LED itself in the test set.


Archer, # 276-045 "Mini Green Light Emitting Diode"
Received & tested 07-23-05

This is a diffused, 5mm yellow-green LED that Archer (now known as Radio Shack) sold in its stores sometime in the 1970s.
The writing on the back of the package indicates it has a luminuous intensity of 4.5mcd at a drive current of 40mA.

Unlike most modern 5mm LEDs in epoxy bodies, the cathode (-) lead is the long one, and the anode (+) lead is the shorter one. The flat spot on the flange (at the bottom of the epoxy body) is next to the (-) lead.

Left: Package this LED came in.
Right: The LED itself in the test set.



Spectrographic analysis of this LED.
USB2000 spectrometer graciously donated by P.L.



This is a high-brightness red LED that a user of this website donated in early-March 2005.

The LED comes in a water-clear epoxy case, and uses a GaAs (gallium arsenide) substrate; which is apparent because the die (light-emitting region) is opaque black, and the light from this LED is a deep red, probably greater than 660nm.

It is not known who made this LED.


Here is a photograph of the LED itself.


And here's one of its beam at ~12" from the test target.
Measures 75mcd on the test target.

Very narrow viewing angle (est.2°) accounts in large part for this measurement - very high by 1970s LED standards.



This is a fairly large, 4-digit red LED display. I don't know where it originally came from or who made it, but I'm pretty certain it's a 1970s product so I have it on the right page.


Here's a picture of it, showing the male edge connector. I'm guessing a matching female connector mated with it, and the display went in a DMM, clock, or other instrument that needed at least 4 digits. Hmmm, I don't see any decimal points or colons, so that kinda rules out DMMs and clocks.
Nevertheless, here it is for everyone to gawk at. :-)

Update 07-24-05): A fan of the website who's work with LEDs and other light sources I trust states he has a digital clock with no colon in it; so it is within the realm of possibility that this display may have been used in a clock after all.

I should thank Scott T. of Kentucky for this LED, too.
Thank you, Scott!!!




These unusual guys are "AC LEDs". They have two standard chemistry yellow-green LED chips inside, but they're connected opposite of one another. So when you connect them to a low voltage AC circuit, both chips glow alternately; one chip on the high side of the AC cycle, and the other chip on the low side. Because alternating current is usually found at 60Hz or higher, they appear to be both on at once.

Notice if you will, the unusual, flat gold plated leads, and the inverted conical case style. This case style ensures the LED can be seen from a wide viewing angle; and I'm uncertain as to why the leads were made that way. They honestly look like something that might be found in sophisticated telephone switching equipment from the 1970s.
If you just plugged one of these onto a board, it would orient itself as a right-angle emitter.

Here's a trick I learned in 1975 or so: Take an LED like this, and wire it in series with a standard C7 1/2 Christmas bulb. Add a clear case, and a pair of insulated meter test probes. You now have a test set that can indicate the presence of voltage from 2 volts to 120 volts, AC or DC.
If you don't have an AC LED, a pair of regular ones will work; just wire the two LEDs together so the cathode of one goes to the anode of the other; then hook the two remaining leads to each other in the same way; and treat it like a single LED in this circuit.

A dedicated fan of The LED Museum sent these unusual LED lamps to me.

(Update 05-29-07:) Another website fan confirmed my earlier theory that these LEDs were used in rotary dial Western Electric Trimline telephones in the 1970s and 1980s.
Here's a photograph showing just this!!!




Back in the pioneer days, a number of LED case styles evolved rather quickly. This style has a thick brass washer or base of some kind (possibly a heatsink?) instead of the familiar anvil and post style of internal leadframe. A number of these have turned up in my museum. What I find odd about these is that models with reddish or pinkish tinted cases tend to be yellowish-green LEDs inside. They may have attempted to create a usably bright yellow LED by enclosing a green chip in an orange or pink case, and to some degree (though not entirely), this does actually work.





This is another early case style. Notice the metal bushing or collar on the bottom.
This early red model was intended to be operated at 50mA.

The damage to its case was due to its owner monkeying around with liquid nitrogen. Apparently, this LED lit up like a strontium highway flare when immersed in liquid N2, but this eventually caused the epoxy to fracture.

I believe this is an early Hewlett-Packard part, but like with so many others, I'll have to wait until after disaster recovery to go through tens of thousands of last year's e-mail messages looking for that info. :o
Please be patient.




For awhile, Fairchild Semiconductors was a major player in the LED game. This is one of their 1970s models, the FLV-102. It is a diffused red model, suitable for low ambient indicators and automotive/aerospace "idiot lights".

An especially interesting LED I'm looking for is a Fairchild FLV-104. This was a red LED in a transparent, somewhat elongated 5mm case. It has an unusual ovoid die, and has an equally unusual narrow beam viewing angle of approximately 2° by 3°. It was known to be available as late as 1980 to 1985. It was originally developed in 1973.



I received two of these LEDs from a website visitor (R.W.) in the Netherlands on June 14, 2004 (thank you!!!), along with two phosphor pink LEDs and two 450nm diffused blue LEDs (thank you for those too!!!).



This is a red LED, which according to the person who sent them, came out in 1978. It has no die cup that I can see (the LED die appears to have been mounted directly to the top of the leadframe assembly), and was designed to be visible to around 180 degrees.
It comes in a very small (possibly T 1/2 or T 3/4) plastic case, and emits a deep cherry red glow at around 660nm.



This is PAGE 3 of the 1970s exhibit. Go here to return to PAGE 1.








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