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> <3DDCFAEE.1FD9D60@webaccess.net>
Date: Fri, 22 Nov 2002 00:35:20 GMT
NNTP-Posting-Date: Thu, 21 Nov 2002 16:35:20 PST
> Chuck Simmons wrote:
> > J81 wrote:
> >> On Thu, 21 Nov 2002 14:15:16 GMT, Kevin McMurtrie
> >> wrote:
> >> >In article <firstname.lastname@example.org>,
> >> > J81 wrote:
> >> >>I've got this half-baked idea to use a piezo ignitor to power an LED
> >> >>which needs 2.5v at around 15ma to 20ma. I'm currently under the
> > The piezoignitor is a capacitor. If you connect it's output to a larger
> > capacitor, you will get a lower voltage that you might be able to
> > measure with a high impedance voltmeter or electrometer. The voltage
> > tells you how much energy you have by E=V^2*C where E is energy in
> > joules, V is voltage in volts and C is capacitance in farads.
> Isn't energy lost though?
> If it isn't, then a large enough capacitor to cause an output of 10v or so,
> and a bridge rectifier may work.
There should be no real loss of energy. The equivalent circuit of a
typical piezoelectric device at low frequency is a capacitor in series
with a resistor and the whole thing having a shunt resistor. The
resistors are usually respectively very low and very high. The
piezoelectric constant can really be expressed in terms of charge.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons email@example.com