GE YELLOW SiC #SSL-1 LED FROM THE MID-1960s
Last update: 08-25-2020
I received a GE SSL-1 SiC (silicon carbide) yellow LED from R.L. in South Carolina USA on 06-21-08!!!
I've been looking for one of these LEDs for years now, and I can now say that I have one!!!
Thank you very much R.L.!!!
It comes in a metal can with what I believe is a glass positive (magnifying) lens in the end.
The die appears to consist of a mainly cubical block, and its primary composition is SiC (silicon carbide); a material most people know of only as the hard, abrasive crystals used in grinding wheels and some sandpaper.
This is a 5mm of fairly recent pedigree (left) compared with the GE SSL-1 (right).
This is a photograph of it in my LED test set, being operated at a current of ~29.4mA.
You'll immediately note that this LED really isn't all that intense; its light output could probably be measured in µcd (microcandelas).
The intensity is simply too low to measure with the instruments at my disposal.
According to the packaging materials, this LED has an output of 14 foot-lamberts at an If of 50mA.
This is the package it comes in to prove that I really have the SSL-1.
And here are four data sheets for this LED, courtesy of S. Hayes:
Here is a "testimonial" from somebody who used this LED for a specific purpose (his name and email address were omitted to help protect his privacy; no changes to grammar, syntax, or spelling were made):
"I was happy to find your web page with detailed info on the SSL-1. I have one of these devices. Attached are a couple of photos. I used this one in the late 1960s when I was working at Eastman Kodak Company. I was developing instruments for measuring photographic film quality, specifically densitometers. I was using multiplier phototubes as detectors. To calibrate them, I used the SSL-1 because of its stability of light output and ability to be switched rapidly between different output levels, characteristics that could not be achieved easily with other light sources. In the second photo, the SSL-1 is at the top. It is way out-shined by a the bottom modern LED."
The photographs and press release below were graciously furnished by the same gentleman.
THANK YOU EVER SO VERY MUCH, KIND SIR!!!
Press release (in .PDF format) that was released in the late-1960s.
Spectrographic analysis of this LED; newest (01-13-13) spectrometer software settings used.
Spectrographic analysis of this LED; newest (01-13-13) spectrometer software settings used.
Spectrometer's response was narrowed to a band between 550nm to 580nm to pinpoint peak emission wavelength, which is 566.789nm.
Spectrographic analysis of this rather antique (circa. mid-1960s) LED.
Baseline was artificially lowered with Photoshop to show actual spectral output.
And I had to place the LED directly against the sensor aperture of my USB2000 spectrometer to obtain any plot at all.
Same as above.
Baseline was artificially lowered with Photoshop to show actual spectral output.
And I had to place the LED directly against the sensor aperture of my USB2000 spectrometer to obtain any plot at all.
Same as above.
Only this time, the plot was adjusted via SpectraSuite software (included with my USB2000 Spectrometer) to be closer to full scale.
Note the *VERY FAINT* line at 393.9nm in the near-ultraviolet region of the spectrum. This line was not evident with quiescent conditions, so it had to be generated by this LED. Let's take a closer look at it...
Here is the near-UV line itself; the spectrometer's response band was narrowed to a range of 390nm to 400nm.
Same as the plot above the last one; spectrometer's response band narrowed to a range of 490nm to 720nm this time.
The If was 50mA (its rated current) for this analysis.
The If was 50mA (its rated current) and newer software settings were used for this analysis.
Spectrographic analysis of this LED; yet newer software settings were used for this analysis.
Spectrographic analysis of this LED.
Spectrometer's response narrowed to a band between 540nm and 590nm to pinpoint peak wavelength, which is 568.52nm.
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