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YELLOW 585-600nm


Spectrum of a typical AlInGaP yellow LED.

Radio Shack # 276-351 5mm Yellow LED, $2.79 (for 2)
Purchased 03-22-09, tested on 03-25-09
This is a yellow LED in a water-clear 5mm round ("through hole") epoxy package.


Beam photograph on the test target at ~12".

Measures 3,830mcd on a Meterman LM631 (now Amprobe LM631A) light meter.
Viewing angle is listed as 30.

Mr. Meter sez that this LED's Vf is 1.960 volts at an If of 19.28mA.


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



Radio Shack # 276-0010 Rectangular Yellow LED, $1.79
Purchased 02-27-09, tested on 03-04-09
This is a wide-angle rectangular yellow LED in a water-clear rectangular epoxy package.
Although the packaging materials indicated that there should be two (2) LEDs in the pack, there was only a single one.


This is what the LED itself looks like.


Beam photograph on the test target at ~12".

Measures 3mcd (yes, 3mcd! on a Meterman LM631 (now Amprobe LM631A) light meter.
The packaging materials indicate that this value is 50mcd; perhaps I simply ended up with a bum LED. Just by "eyeballing" it, the intensity does indeed appear to be quite low; I can stare directly into the lamp with no discomfort.

This is a very wide-angle LED; and if I've told you once, I've told you 2,458,770 times:
Wider viewing angles always, ALWAYS, ALWAYS equal lower mcd values!!!
Viewing angle is listed as 154.

Mr. Meter sez Vf is 2.264 volts at an If of 19.28mA.


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



Optek Technologies # OVL F43C7 yellow LED
Received 12-24-07, tested 12-31-07
This is a amberish-yellow 5mm LED in a water-clear colorless epoxy body.
It produces a slightly but noticeably smoother beam than is usual for nonphosphor yellow LEDs.

Peak emission wavelength appears to be ~593nm, in the amberish-yellow region of the spectrum.


Measures 4,400mcd at a drive current of 19.28mA.
Viewing angle appears to be 25-30

Spectrographic plot
Spectrographic analysis of an Optek Technologies OVL F43C7 yellow LED.



Radio Shack yellow LED from their # 276-1622 assortment pack
Purchased 05-03-07, tested 05-04-07
This is a 5mm round LED in a water-clear epoxy case. It produces a circular beam with a central hotspot and ringy corona. This is a very typical beam configuration from a 5mm non-phosphor lamp, and is nothing whatsoever to be concerned about.


Measures 4,020mcd at a drive current of 19.28mA.
Viewing angle appears to be 25-30


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




LEDs International, amber/yellow LED, L15NAYH82C
Received & tested 02-20-07
This is a 5mm round LED in a water-clear epoxy case. It produces a circular beam with an unusually smooth profile for a non-phosphor lamp.


Measures 4,700mcd at a drive current of 19.28mA.
Viewing angle appears to be 25-30


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




5mm yellow LED, ETG, part # ETG-5TS590-30
(Rec'd unknown, tested 11-23-06)

This is a 5mm yellow LED in a water-clear epoxy body, which emits at ~590nm in the yellow region of the spectrum.
The operating chemistry is probably InGaAlP (indium gallium aluminum phosphide).


At a test current of 19.28mA, intensity was measured at 4,320mcd.
Vf was measured at 2.458 volts.
Color is significantly less reddish than is depicted in this photograph.

Spectrographic plot
Spectrographic analysis of this LED.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



5mm yellow LED, Manshun Int'l Ltd, part # YLYL5111A-OO
(Rec'd 03-22-06, tested 03-24-06)

This is a yellow LED, which emits at 585-595nm in the yellow region of the spectrum.
The operating chemistry is probably InGaAlP (indium gallium aluminum phosphide).


At a test current of 19.28mA, intensity was measured at 5,710mcd.
Published intensity values range from 3,000mcd to 4,200mcd.
Vf was measured at 2.035 volts.
Color is significantly less reddish than is depicted in this photograph.
I'm not equipped to measure beam angles at all. It is published as 15.

Spectrographic plot
Spectrographic analysis of this yellow LED.
Ocean Optics USB2000 Spectrometer on loan from TWO-CUBED.



Manufacturer unknown
Received 07-03-04, tested 07-04-04
A fan of the website (J.R. in Michigan) sent 11 LEDs (thank you!!!), and two of these yellow LEDs were among the goods. This is a custom-moulded LED in a water-clear epoxy package. I don't know who makes the die (light-emitting chip) inside this LED, so please do not ask, thank you.
This appears to be a 585-590nm yellow LED. The working chemistry is probably GaAsP (gallium arsenide phosphide), with a low arsenic/phosphorus ratio of maybe 20/80 to 10/90, on a gallium phosphide substrate.


I cannot obtain a beam photograph at the correct distance, so I photographed the LED itself next to a standard 5mm LED. This LED is the one closer to the bottom of the photograph, with the bends in its wire leads.


And here's a picture of its beam on the test target from approximately 4".
This LED appears to have an oval beam of 20-25 degrees by 30-35 degrees; since I do not have the equipment for measuring viewing angles, this is an eyeballed value. Brightness is too low for me to obtain a measurement using the equipment at my disposal.
Just by eyeballing things, it appears to be around 15-25mcd.



UltraLEDs 5mm Yellow LED, (www.ultraleds.co.uk)
(Recieved on 03-04-04, tested 05-03-04)
This is a 5mm (T1 3/4) LED in a clear epoxy package that a fan of the website sent in early March 2004.

It produces an amberish-yellow beam with a dominant wavelength (where you would point to on a color chart) of approximately 586nm. My spectrometer is still broken, so I cannot confirm this with a measurement.

The beam consists of a central square region with a dark circle in it (a magnified image of the LED's light-emitting chip, or "die" as it's called), surrounded by a dimmer region, surrounded by a brighter corona. This corona has four dark lines running through it, originating at the corners of the die.


Measures 4,900mcd at a test current of 17mA.
The viewing angle appears to be around 12. I don't have an instrument to measure this with though, so this is just a guess.



Wilycon "Ultra Yellow" 5mm round
This is a 5mm round LED in a water-clear case. Brightness was measured at 7330mcd at 20mA, and the narrow primary beam was irregular & off-center with a prominent outer ring.
beam
Dominant wavelength appears to be in the 585-588nm range.

Yellow: $80/Kpcs for 50000pcs order.
small qty: USD$0.50/pc Minimum USD$10 worth.



Toshiba, model TLYA157P, Hosfelt Electronics 25-275, $0.12 apiece
Here is a decently-bright, not quite sodium-yellow LED in a clear, T1 3/4 case. It is rated at 550mcd in the Hosfelt catalogue, and it seems to live up to that figure.
The beam is fairly well-defined, with a weak, oddly-shaped spot in the center, a faint brownish-orange zone outside the main beam, and a faint, somewhat "shamrock-shaped" pattern visible within the main beam. The beam itself seems divided into three distinct zones: a brighter central area containing a dark spot, a dimmer zone beyond that, and the much dimmer brownish zone after that. The central "hot spot" commonly found in high-brightness LEDs is small and dark, and shaped like a circle with four thin lines at the 9:00, 12:00, 3:00 and 6:00 positions. This unusual artifact is a result of the wirebond inside the LED, which is essentially an "X" shaped structure, designed to distribute more current more evenly across the face of the die at the expense of total light output.
The spectrum is not exactly narrow, but is more so than some other LED models. It peaks in the yellow region - I'd say around 580 to 585nm, which is slightly greener than the sodium line at 589nm. There is weaker output in the mid-red and well into the green - but most of its light comes from the yellow part of the spectrum.

If this were a green LED, it would be great for St. Patrick's Day because of the distinctive shamrock-shaped beam. Otherwise, use it as you would any other yellow model. This would be a nice LED to use in "realistic" model train sets, to use as simulated sodium-vapor streetlamps.

beam profile
And here's its beam profile on the test target.

UPDATE: 02-07-02
It has long been said that a mysterious secondary band in the IR is emitted by this LED, and I have now captured that phenomenon with a camera and made it a mystery no more.

The arrow in these pictures points to a band of IR energy at around 900nm in the output of most Toshiba and AND orange and yellow LEDs. Although the human eye can't see this energy, many instruments can, and will give you falsely high readings of visible output power because they're also sensing the IR and adding it to the total. Only a specially filtered instrument which can remove the IR and retain the visible will give you accurate power readings on this LED.

This band appeared in all images taken (it also appears live in the LCD viewfinder), and is of the correct color and intensity for my particular camera and the projected wavelength of the IR band involved, so there is no mistake.



Nichia, NSPY500S (New in late 2001), pricing is likely $8 apiece in small quantity.
Nichia America has always been known for their spectacular InGaN green, blue-green, blue and white LEDs. But this is apparently their first venture into the yellow LED market, and I was rather pleasantly surprised at what I saw when I hooked one of these babies up.
I expected to see something along the lines of their "D" rank white LED, and that is a pale yellow color. But these have a fully saturated, pure looking yellow that I've never seen before in an LED.

I also noticed something really fishy about the spectrum - it has almost no blue in it! The nearest InGaN "yellow" to this is the NSPW500BS rank "D", and it has plenty of blue. But this one has a spectrum very low in output from violet to blue-green, then intensifying through mid-green, and pretty much peaking from yellow-green through mid-red. There may be a slight dip in the orange region, but it isn't a huge dip.

The functional mechanism is a GaN type blue chip with a yellow-emitting phosphor over it. The almost absolute lack of blue in the spectrum is a result of careful tuning of the phosphor formulation; they were made this way on purpose to obtain the more saturated yellow light.

This picture shows a NSPW500BS rank "S" color "C" white on the left, a NSPW500BS rank "R" color "D" in the center, and this new NSPY500S on the right. In reality, the white LED appears a bit more bluish, and the pale yellow "D" rank is a bit whiter.
The new yellow looks pretty close to correct.
For this picture, the camera was set to Fluorescent Bulb.

(Update 04-13-06)
Spectrographic plot
Spectrographic analysis of this LED.



Spectrographic plot
Same as above; newer spectrometer software & settings used.

USB2000 spectrometer graciously donated by P.L.




Russian manufacturer, circa 1973, model # KA101
From Russia with love, these extremely rare LEDs showed up in the mail in late November 2000.
These LEDs are very unique in several ways. First is their age: these were made in the former Soviet Union somewhere between 1973 and 1974. Secondly, they are yellow (actually, greenish-yellow) LEDs. Lastly, the "active ingredient" is silicon carbide - a material that most people would think of as an early 1990s blue LED technology.

Russian yellow SiC LEDs This picture shows the two miniscule, crudely-made LEDs next to a modern 10mm plastic LED.

They are barely larger than the head of a common pin, and are deceptively simple in construction: a crystal or block of silicon carbide sandwiched between two metal plates and encapsulated in a tiny droplet of glass.

When you apply approximately 5.5 volts DC at room temperature, they glow a very dim, greenish yellow color. Their output power could be measured not in milliwatts or even microwatts, but in picowatts.


As you can see by the pictures, the inner face of the LED chip glows a yellow color near one of the electrodes, while the remainder of the chip glows a ghostly, "radioactive" greenish color. Brightness is rated at 10 microcandelas (0.01mcd).

Initial testing shows these are real diodes - they do not conduct or glow when reverse-biased. Forward current is stated as 10mA nominal, 20mA max, and (if I understand the Russian writing), 40mA in pulsed operation.
Their spectral output and forward voltage varies wildly depending on temperature. But at room temperature, the spectrum peaks near 575nm, and extends as far as 450nm in the blue and almost 700nm in the deep red.
The dopant (a material normally needed to form the P-N junction in any semiconductor) is not known.

This LED is significant because it predates other yellow LEDs by at least several years and because it is made from silicon carbide instead of gallium arsenide phosphide or compounds containing those elements; which are the basis of all other red, orange, yellow, and yellow-green LEDs.

Additional photographs can be found in the LED Museum, in the 1970s (page 2) exhibit.



Hewlett-Packard, model HLMP-DL00, older type, estimated $0.30 to $0.50 each, availability unknown
This is a more "traditional" narrow-beam super bright yellow model. Packaged in a clear, T1 3/4 case, this LED emits a bright yellow central beam, surrounded by a sodium-yellow (more orangish) outer ring. The central hot area is essentially square in shape and reasonably uniform in brightness; its divergence appears to be around 10 degrees or so.

Beam profile
Too many more of these, and the target will have holes burned in it. :)


AND model AND 180HYP / Toshiba TLYH180P (U2), Hosfelt Electronics 25-335, $1.25 apiece
Here is another yellow LED with an unusual "shamrock" beam pattern.
Packaged in a standard clear T1 3/4 case, this bright yellow LED has several characteristics which make it very unique.
  1. Bright yellow, slightly rounded square central beam.
  2. An unusual "shamrock" pattern embedded within a dimmer coronal zone, and
  3. A very distinct, bright orange outer ring and dim, brownish-orange outer corona beyond that.
This particular LED has probably the most unusual beam pattern I've seen since the nitride series blue & green models started showing up.
This LED also has an "X" shaped wire bond pad, like the other yellow Toshiba model outlined earlier. I believe this contributes to creating the shamrock shape within the LED's beam pattern.
When shone at a more distant target, the square central beam becomes slightly diffuse, and a very narrow pinpoint of brighter light appears at the center. The orange outer ring pretty much dissipates at greater distances, and isn't really an issue when the LED is used that way.

beam profile
Beam profile on this unusual lamp. The broken camera simply couldn't focus well enough to capture the finer details.



WHITE 5500-6500K InGaN+phosphor 
ULTRAVIOLET 370-390nm GaN 
BLUE 430nm GaN+SiC
BLUE 450 and 473nm InGaN
yellow Silicon Carbide
TURQUOISE 495-505nm InGaN
GREEN 525nm InGaN 
YELLOW-GREEN 555-575mn GaAsP & related
YELLOW 585-595nm
AMBER 595-605nm
ORANGE 605-620nm
ORANGISH-RED 620-635nm
RED 640-700nm
INFRARED 700-1300nm
True RGB Full Color LED
Spider (Pirrahna) LEDs
SMD LEDs
True violet (400-418nm) LEDs
Agilent Barracuda & Prometheus LEDs
Oddball & Miscellaneous LEDs
Programmable RGB LED modules / fixtures
Where to buy these LEDs 
Links to other LED-related websites
The World's First Virtual LED Museum
The Punishment Zone - Where Flashlights Go to Die
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