Finding a forward voltage drop across an LED

Re: Aging effect on voltage drop

Grumpy_Mike:

Data sheets don't tell anything in this direction

Yes the do they give a maximum and minimum range for this parameter.

I understand (now, thanks) that the "typ." and "max." values for VF are not only individually different,
but may change over time for a given led.
(Besides a temperature dependency of course)

Grumpy_Mike:

Any real life experiece with that?

Yes

It it usual that VF will grow with age ( making current decrease in a given resistor controlled circuit )?