in article z3pGb.187079$ snipped-for-privacy@twister.rdc-kc.rr.com, Frank Eva at snipped-for-privacy@wi.rr.com wrote on 12/24/03 3:12 PM:
They are using a regular "blue" led with the white phosphor, then an amber colored casing to absorb any extra blue. You can achieve a similar effect with a regular "bright white" leds and Sun 8410 (daylight) filter material, or even amber glass paint.
I've not tried the new miniatronics clear case white (yeloglo) which claim to be incandescent colored.
There is a company, ledtronics, which is a supplier from whom you can't buy, which makes both Pale While and Incandescent White leds. I obtained samples at one time. They were pretty good and had clear cases. One of the samples (5mm) was cylinder shaped with a flat front: almost exactly the size for an F3/7/9 headlight. Too bad I could only get one and I've seen them nowhere else.
You can get ultra-bright leds of various colors, including white and they can be exceedingly bright, indeed if run at their full rated voltage. The "bright whites" I got from Allied Electronics left after images if looked at straight on. Many of these leds, however, have a fairly narrow light projection: 13 to 20 degrees, and are quite dim off axis. But take care with the resistors used to limit the current: if the voltage is too high, the leds burn out quickly. If I calculate, I get 620ohms or so for my 4v leds and digitrax decoders; but I use 820ohms to allow for a safety margin and the white ones are still very bright.
I still like LEDs for their coolness (not in the sense of hip, but rather temperature) and longevity.
Ed.