The fundamental problem is that the swinging cap can't deliver enough energy
to charge itself, AND run the device.  This circuit is a perpetual motion
machine.. The cap has to deliver more energy than it takes to charge itself,
and once you start bumping up VCC, it's running from it's own output.

You could power a different chip this way, IF the chip dosen't draw too
much.
You could use the signal from the pin to run a driver from a solid 3V rail,
and that could pump up to 5V at a lower current, into the processor.
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