Ruben J=F6nsson wrote:
>>> A 2000uF capacitor charged to 10V.
>>
>> Yes, but you have to drain it to zero to get the whole 100mJ out.  In
>> practise you'll need a bigger cap or higher voltage.
>
> So - drain it to zero.

That is theoretically possible, but back here in the real world that would
require a circuit that can be usefully powered down to nearly zero volts.
It also leaves no margin for tolerance, inefficiency, etc.

If you want to actually *use* the stored energy, you very likely need it to
be over a limited voltage range that does not go down to zero.  About the
only exception I can think of is for heating.  You can switch a resistor
accross the cap and it will eventually convert all the energy stored in the
cap to heat.


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