I have a number of leds, green Optek OLVFG3C7, that seemed to havve changed their operating characteristics.
I started out with a 1k resistor in series with about a 6.5v ps. Even at this low current they are really bright. Well after a few weeks a number of them went dark. Upon test the dark ones were still good and just needed a boost in voltage. I cranked up the ps to around 9v. All went well for 3 weeks and now a few more will not light.
Is it normal for leds to age and change like this? Nothing in the data sheet seems to indicate a minimum forward current is required, and the luminisity vs current is pretty linear from zero on up.
Thanks for your ideas