--exray-- wrote:
Chuck Harris wrote:


Electrolytic capacitors are self adjusting for working voltage (to
some degree). If they are operated for a long time at 50% of their
rating, the oxide reduces in thickness, and they become higher
capacitance, and lower working voltage. If you try to increase their
operating voltage, they will draw too much current. They will either
adapt to the new higher voltage, or they will blow up from the heat.


Thats very much true with older caps up to about 1970. But later model
caps don't exhibit this 'memory'.

It is all about the electrolyte. The older electrolytes tended to eat
the oxide layer pretty quickly. The manufacturers rated them for a
1 to 2 year shelf life... longer if they were in continuous use.

There have been alot of improvements in the electrolytes, and now the
caps last virtually forever. But the oxide thickness still determines
the tolerance, and as such it still changes with temperature, age and
voltage. Just not as much as it used to.

-Chuck

-Bill