Re: gEDA-user: LED in reverse

[Karel Kulhavy <clock@xxxxxxxxxxxxx>]

On Sun, Nov 19, 2006 at 10:18:31AM -0500, DJ Delorie wrote:
> 
> > How is it possible that the LED withstands 20mA in forward and is
> > destroyed by 0.5mA in reverse?
> 
> Trick question.  Imagine an IDEAL current source.  It would be able to
> produce 0.5mA across an air gap, for example.  Imagine how many volts
> would be required to do that.
> 
> Now imagine that ideal current source across a diode.  In the forward
> direction, it would produce a fraction of a volt until the diode
> started conducting, no harm.  In the reverse direction it would apply
> enough voltage to hit the breakdown, at which point the diode starts
> conducting.

But the breakdown means that electron go through the diode just the other way.
Why do the atoms stay the same when hit by electron from one side and something
permanently changes in them when hit from the other? Are they asymmetric?

CL<
> 
> 
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