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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Piezo Ignitor to power an LED -- any ideas?
References: <email@example.com> <firstname.lastname@example.org> <email@example.com> <3DDD8241.5D571789@webaccess.net>
Date: Fri, 22 Nov 2002 03:30:51 GMT
NNTP-Posting-Date: Thu, 21 Nov 2002 19:30:51 PST
John Larkin wrote:
> On Fri, 22 Nov 2002 01:03:14 GMT, Chuck Simmons
> >I don't see any need for high voltage diodes. (I actually don't see the
> >need for the bridge at all because the main pules is DC anyway.) The
> >capacitor will insure low reverse voltage on the diodes. You are a
> >little sensitive to current in that the charging current may be high.
> Isn't a piezo a capacitor? How can it create a net DC current?
When you apply a force to a piezoelectric material, the result is a
charge. The units of the piezoelectric constant can be
coulombs/kilogram. When you compress the material, there is an electric
field and therefore charge. If the material is free to oscillate as a
mechanical oscillator then AC will result. However, removing charge will
damp the oscillation.
I ran across an interesting reference here:
This has to do with recovering some energy from walking using PVDF which
is a plastic material (I think the trade name is Kynar). The efficiency
is very high because the material can be made in thin sheets stacked for
low voltage and high capacitance.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org
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