Olin Lathrop wrote:
> That's not the point.  Measure the current/voltage curve of any LED you
> have.  It will demystify LEDs in general and you will learn something.

The problem I had was that I was thinking of LED's as being distinct 
from normal diodes.

I understand diodes completely:
    * They only allow current to flow in one direction
    * They always have 700 mV across them (or thereabouts)

If the supply voltage is less than 700 mV though, then negligible 
current flows.

Now the only difference with an LED is that instead of 700 mV, you have 
maybe 2.2 volts.

I know what the current/voltage curve of a diode looks like. For a 2.2 
volt diode, it should look something like as follows:
    * When the supply voltage is less than 2.2 volts, the current flow 
is extremely low (in the micro or nanoamps)
    * As the supply voltage hits 2.2 volts, the current curve starts to 
rise, and then it quickly becomes a near-vertical line.

The current curve doesn't shoot up to the sky in a perfect straight 
line, but it's pretty straight. Zeners of course have a straighter line 
(but of course you use them in reverse bias).

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