> i=C dV/dT calculation is indicating over 1300 uF
> .............
> fairly unreasonably large capacitor for this circuit.

A 5V 0.1F isn't much bigger than a button cell. I strip them out
of old VCRs all the time. And some are up to 1F

--
http://www.piclist.com hint: The PICList is archived three different
ways.  See http://www.piclist.com/#archives for details.