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Super Capacitors



At 11:08 AM -0600 11/11/98, Gary Karshner wrote:
Ed,
Electrolytic capacitors make a poor choice for RC time constant
measurements. First their capacitance is at best within 10% of their stated
value. It is typically an under estimate of the value because of the way the
are used in filtering. Second they have a low leakage resistance ( the order
of a megohm and voltage dependent). The leakage resistance can be viewed as
a built in resistor in parallel with the capacitor. In addition some of the
Pasco units also have a low internal resistance (the order of a megohm) that
can act like a leackage resistance as well if your using it to measure the
voltage across the capacitor. A third effect is a high ESR (effective series
resistance) that as the name implies can be view as a resistance in series
with the leads of the capacitor. This one is especially true for some of the
"super capacitors" that have capacitances in the order of Farads.

How do those "super caps" work? Is this "capattery"
<http://www.evanscap.com/Capattery.html > the same thing? How do they get
so much capacitance in such a small package?

Thanks,
Larry