Why do yellow (amber) & lime green LEDs suck? Answered
In my experience, I have dealt with many colors of LEDs, and from what it seems, red, neon green, and blue LEDs tend to be pretty good at producing light as well as surviving abuse. They also tend to require the least amount of current. However, I have found that almost all the the classic lime green and yellow LEDs are very different, and generally don't give much light output even with significant amounts of current! I have a couple of ultra bright red and blue LEDs at the moment that will glow bright enough to see them easily only a 100 microamps! That is something I simply cannot do with any of the yellow or green LEDs I've ever had!
A bit of research shows that GaN and InGaN is commonly used for the blue and neon green LEDs, while GaAsP, AlGaInP, and GaP are typically used for the old-school red, amber, and lime green LEDs. I imagine brighter and more rugged yellow LEDs must exist, given their use in stop lights and road signs. Do they in fact exist? Or is our yellow LED technology still stuck in the 1980s due to little interest in them and little to no R&D?
The reason I ask is because I want to build a light source utilizing amber and blue LEDs to mimic white light, and I'm purposely trying to select colors which will give a white light w/ extremely low CRI. However I want yellow LEDs that are a closer match to blue LEDs in terms of intensity, and preferably, efficiency.
I did some small scale experiments with some unknown LEDs salvaged from christmas lights, and I am impressed how poorly this light renders colors! (and how quickly my 15 ohm resistor went up in smoke driving all the yellow LEDs I had to use to equal the light from a couple of blue LEDs!) although the light hitting white paper appears purplish white, colored objects seem ghostly and take on either a deep blue, muddy grey, or yellow. Perfect for maybe a haunted house ambient lighting! Add a 50Hz capacitive driver to get some good flicker and presto, worst light quality EVER! :D