> >Are people claiming one diode goes to threshold and then the others start
> >being forced to threshold as that single diode avalanches? Is that the
> >mechanism that causes voltages to be "shared"?
>
> That's how I'm reading the argument, Tom.
>
> I repeat: if the data sheet doesn't say 'controlled avalanche device',
> don't rely on it being so.
"Controlled avalanche" means the diode has a breakdown curve
knee, where reverse current suddenly skyrockets. Engineering
references from Motorola state that "Normal circuit operating
voltages should be below the minimum breakdown voltage" (which
is found by a test that establishes a "knee" in current reached
when raising the reverse voltage).
Now they don't say these knees are all the same, they just say the
diode has at least this high of a knee in the reverse current curves.
They don't even specify the current.
If you depend on this knee establishing the division, then it seems
you are breaking the design guideline that normal operating
voltages should never reach that point. They warn if you constantly
avalanche the diodes, life can be reduced.
So let me ask again, what keeps one or more diodes from being
operated contrary to manufacturer's specs and suggestions when
you series a whole string with nothing but diodes?
73, Tom W8JI
w8ji@contesting.com
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