Unusual LEDs and Where To Get Them

This Page Will Expand - Still Under Construction!

LEDs of Unusual Color
RGB Flashing LEDs
LEDs Powerful Enough to Require Heatsinking

LEDs of Unusual Color

ETG makes a purple LED. This is not violet or UV or "near UV" but a pink-lavendarish purple LED which has a deep blue LED chip with some orange-glowing phosphor over the chip. The part number is ETG-5AX420-15. This is a somewhat narrowbeam 5 mm LED with a nominally 15 degree beam. The core of the beam is a slightly pinkish purple-lavendar while the edges of the beam are slightly pinker than the core of the beam. Craig Johnson's Pink LED Page has photos of a more-pink-than-usual sample of this part.

ETG now makes a related pink LED, part number ETG-5AX440-15.

There is concern about degradation of pink LEDs and similar purple LEDs. The manufacturer claims a phosphor life expectancy of 10,000-plus hours. My testing on an ETG-5AX420-15 (purple) so far indicates that this LED will remain a purple to lavendar LED with negligible to zero loss of light output after 10,000 hours at 20 and probably even 30 mA. The biggest concern is color drifting towards bluish white or possibly blue, so even if the color changes a lot it will remain basically purple, lavendar or violet of some sort and should have no trouble doing so for 10,000 hours at full power.

More info - email lloyd@etgtech.com. Last time I checked, they said smaller orders of 10 pieces of these LEDs are welcome and they accept PayPal.

Kingbright makes an extremely deep blue, almost violetish blue 450 nm LED, their L7113NBC. Light output is about 25-30% of that of the brightest 470 nm blue LEDs. The minimum order is a steep 500 pieces even through their distributors.
LEDTronics also makes a 450 nm blue LED, their L200CWB-1KB-15D. Light output is like that of the Kingbright 450 nm blue, roughly 25-30% of that of the brightest 470 nm LED lamps.

Non-UV violet LEDs? Uniroyal Optoelectronics makes them. Actually they are more of a blue-violet or a violet-blue, with dominnt wavelength supposedly 430 nm and peak wavelength rated at 416 nm for some and 420 nm for others. The 416 nm ones look generally a very bluish violet, slightly bluer than that of 405 nm "UV" LEDs. The 420 nm ones look more blue, slightly deeper in color than those common/cheap 430 nm whitish-violetish blue ones and sometimes looking more pure blue if you look directly at them from close range or from within the beam. Objects illuminated by the light can look more violet - human vision often works funny that way with narrowband violet-blue light. The color is not extremely deep/pure.
Although these are brighter than "UV" LEDs, they are dimmer than all blue LEDs with gallium nitride or indium gallium nitride.

The narrower beam ones may not be perfectly safe to stare into from within the beam and all models might be unsafe to stare into for prolonged periods at extremely close range - visible violet can be hard on the retina above some certain intensity.

RGB Flashing LEDs

ETG makes such a thing. The part number is ETG-2SE-RGB-IC. This is a flattish, roughly 5 by 6 mm LED lamp with 2 leads a little further apart than the standard .1 inch. Inside is a red LED chip, a green one and a blue one and an IC. The LED lamp alternates between one mode where the different colors fade from one color to another and a rapid flashing mode. In the flashing mode, sometimes 2 colors are on at once. Illuminate a wall with this from a few inches to about 1 foot away and you can create a "technicolor fireplace" effect. A few of these can make your living room or your bedroom your own private nightclub lounge room!

Photos and further description in Craig Johnson's RGB LED Page.

UPDATE 8/20/2002 - ETG now makes a version in a standard 5 mm (T1-3/4) case with standard lead spacing, the ETG-5SE-RGB-IC. My sample flashed and pulsated at a slower rate than my sample of the ETG-2SE-RGB-IC. Also, the standard shape and size 5 mm part had distinct beams that went into slightly different directions and hardly mixed together at all. This may have an interesting effect if aimed at a wall from maybe a foot away.

POWER: I am still trying to get some official power data besides a nominal voltage drop of 3.6 volts and to treat it like a regular InGaN LED, but for now I feel safe operating this from a nominally 4.5 volt supply through a 33 ohm 1/10 watt (or larger) resistor, or from a nominally 5 volt supply through a 47 ohm 1/8 watt (or larger) resistor. Voltages higher than 5.5 volts will generally require a resistor wattage rating higher than 1/8 watt.
Or, to determine an appropriate resistor, subtract 3.3 volts from the supply voltage and divide the result by the desired current (20 mA for really cool running operation, 30 mA maximum). Multiply this figure by .8 to allow for the "off" time between flashes, then subtract 15 ohms to allow for internal resistance that I have seen in this LED. What remains is a resistor to put in series with the LED. Allow for resistor tolerance and then go to the next higher available value to be extra-safe!
If the supply voltage is high, then put a zener diode in parallel with the LED so that its internal IC is not subjected to high voltage between flashes. I have yet to hear a worst-case maximum voltage, so for now I advise a 5.1 volt zener diode if the supply voltage is more than 5 or worst-case 5.5 volts.

LEDs Powerful Enough to Require Heatsinking

Meanwhile, check out Lumiled's "Luxeon" Page. Luxeon is Lumileds' high power LED lamp. They make 1 watt lamps (some of which can handle about 1.2 watts) and they have 5 watt ones in the works.
Also check out Craig Johnson's Page on such LEDs.

ETG has in the works similar LED lamps with Cree "XB900" dice (chips). ETG has such green and blue LED lamps close to production if not already in production.

Nichia has similar high power LED lamps in the works also.

Then there are heatsinkable multi-chip LED lamps:

Norlux Makes heat-sinkable "Hex" hexagonal units with 40 chips, eight paralleled strings, each with 5 chips in series. Maximum current is 480 mA for their red one and 400 mA for the others. The red one is especially efficient.

Opto Technology makes heat-sinkable TO-66 multi-chip LED lamps.

Written by Don Klipstein.

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