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Re: Non-linear capacitance - supercap




-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Saturday, January 08, 2000 1:30 PM
Subject: Re: Non-linear capacitance


>Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
>
>Gary and all,
>
>Perhaps this is because of hysteresis effects (the same effects that
>make a dielectric amplifier possible as in a recent post by Bert Pool).


I missed that post, could you refer me to it or e-mail me it? Thanks.

> having non-linear elements in a
>voltage divider chain would make accurate measurements quite a
>challenge! :^)


Ceramic is the worst choice for measurement. Can dig up a magazine article
reference if you wish. Any cap is good for power supplies and bypassing, but
measurement and RF brings out problems, like hysteresis, reactances and
other strange high-order effects like 'soakage'. Any dielectric type but
ceramic would probably due, exept rolled polyester with high inductance and
loss.

I would like to see a supercap made from high-Z piezo ceramic. I found an
article about the hysteresis problem - "On the Efficiency of Electric Power
Generation with Piezoelectric Ceramic" Michael Goldfarb
Lowell D. Jones, at
http://www.vuse.vanderbilt.edu/~meinfo/labs/cim/projects/papers/Gogola99.pdf

The paper is about piezoelectric  power generation, and the problem
hysterisis causes. Good analysis. I wonder if mechanicaly loading and DC
polarizing the ceramic stack, and limiting the peak AC could eliminate
hysterisis loss?

Scott