Re: [CAD_CAM_EDM_DRO] On LED's and Gecko Tunings

Andy Wander wrote:

>By this, do you mean that if I apply a voltage of exactly the LEDs rated
>voltage across it, it will draw more current than it is rated for?
>

You can't do that, except for a few minutes, as the voltage drop is
temperature
sensitive. AS the LED heats up, the voltage drop goes DOWN (at least it is
that way in Silicon diodes) and so a thermal runaway condition is
guaranteed.

>And do LEDs really have an "internal resistance", or does it just look like
>they do?
>

Yes. But, the effective resistance is not all true resistance, although
some of it is.
Some of it is also an effect of the abundance of charge carriers in the
junction.
Anyway, the resistance is quite low, probably much less than one Ohm.

>I am starting to think that it is not as simple as an "internal resistance",
>but is more of an "internal voltage drop", based on my tests above which
>gave nearly constant voltage for a halving of current-so the LED isn't
>acting as a resistance, at least not according to Ohm's Law.
>
>

Right, the actual resistance part is quite low. It is effectively
modeled as
a very small resistor in series with an ideal battery of about 2.1 V for a
green LED, and 1.7 V for a Red.

Jon