Search results for query: *

  1. lumengeek

    5mm White LED Fade Test done!

    Interesting to see how you have recorded both phosphor degradation (with tint shift) and epoxy degradation in these tests. Very interesting to see some real results here, goes to show the importance of not overdriving these small devices! Thanks for sharing.
  2. lumengeek

    Cree XR-E Warm White in the UK?

    Just had a look, again they only appear to sell the chips by themselves, rather than the complete stars, at least in warm white
  3. lumengeek

    Cree XR-E Warm White in the UK?

    Hi all, I'm having extreme difficulty in finding anywhere where I can buy XR-E warm white LEDs mounted on stars/heatsinks and available to the UK. The only place I have found is Farnell, but they only seem to sell the chips only! I've ordered bits from DealExtreme before, but they don't seem to...
  4. lumengeek

    LED failure modes

    yes that has just about summed it up, thanks. I was starting to think the die was the most robust part of the LED. I guess due to the rated lifetime of thse things, no-one has really observed any 'true' failures other than epoxy darkening on 5mm leds, and premature die/phosphor failure on power...
  5. lumengeek

    LED failure modes

    thanks for the replies so far, it's interesting to find that the primary reason for failure seems to be the epoxy degrading, and not the chip itself! Could it be that the yellowing encapsulation also compensates for a degrading phosphor? (in other words, the light output from the chip becomes...
  6. lumengeek

    LED failure modes

    Hi all, I was speaking to a work colleague the other day about white LEDs and their rated life of so many thousand hours, but the question is what is the failure mode of the LED beyond it's rated lifetime? (assuming it is cooled properly and not overdriven). I can only assume that the phosphor...

Latest posts

Back
Top