[Diy_efi] DIY-WBO2 circuit now ceramic effects

[Jay Wallace]

Right you are. Quartz (one of the 7 crystalline forms of SiO2, not 
to be confused with quartz glass which is amorphous) is 
piezoelectric. The point that I was trying to make is that ceramic 
is not the same as piezoelectric.There are, in fact, several 
crystal classes for which the piezoelectric effect is forbidden; 
alumina and (cubic) zirconia belong to these forbidden classes.

Jay

At 02:15 AM 6/26/2002 +1200, you wrote:
>How can you say that silicon dioxide (Si02) is not a pizeoelectric crystal
>(especially being a permanently polarized material)??
>It's the basis of all oscillators in common manufacture.
>A very thin slice of Si02 cut at a particular angle (AT/BT/90 etc), which
>will have some natural vibration (I wouldn't try and doubt this, unless the
>the device is at ~-273.6 degrees C), a circuit is built around the crystal
>that will amplify the signal, invert it and then send it back.  This is the
>basic process inside an oscillator.  The crystal itself can be used as the
>filter, it will normally only allow a certain frequency to pass through it,
>ie only a certain voltage frequency will be realised in the movement of the
>crystal and thus produce a consecutive voltage.  However ofcourse, you can
>also get overtone crystal oscillators which just uses an external circuit to
>reduce oscillation at the fundamental frequency, and instead reinforce
>oscillation at some particular overtone (~ n x fundamental; where n = 3, 5,
>7, 9 (not higher that I know of)).
>
>As for the others, some other popular piezoelectric materials are human skin
>and bone (both having very low coupling efficiencies however)
>
>----- Original Message -----
From: "Jay Wallace" <jwallace at nist.gov>
>To: <diy_efi at diy-efi.org>
>Sent: Wednesday, June 26, 2002 1:28 AM
>Subject: Re: [Diy_efi] DIY-WBO2 circuit now ceramic effects
>
>
> > At 11:12 AM 6/25/2002 +0800, you wrote:
> > >md4etal tapped away at the keyboard with:
> > >
> > > > > md4etal tapped away at the keyboard with:
> > > > >
> > > > > > piezoelectric effect???
> > > > >
> > > > > If the heater's driven by PWM, that's electrically nowhere near a
> > > > > piezo element.
> > > > >
> > > > > If the vibration is severe enough, you may however be able to detect
> > > > > it at the sensor's other terminals.
> > >
> > > > Please, think deeper here :  Ceramic resonator, piezo effect,
> > > > ceramic media in the WB ........
> > >
> > > > you were basically making a 10K-20K microphone element with the
> > > > ceramic media in the WB sensor!!
> > >
> > >There will always be a case of piezo effects on crystaline
> > >structures exposed to physical distortion. An engine's exhaust is
> > >probably not the most quiet environment on Earth.
> >
> >
> > Snip....
> >
> > Wait a minute! Just because a material is ceramic (nonmetallic,
> > inorganic) and crystalline does NOT mean that is displays any
> > piezoelectric effect. Generally, ABO3 type compounds with a
> > permanent electrical dipole, like BaTiO3 or PZT, are piezoelectrics
> > but compounds like ZrO2 (oxygen sensors) SiO2 (glass) and Al2O3
> > (spark plug insulators) are not.
> >
> > The long and short of it is that I wouldn't expect mechanical noise
> > (vibration) in a zirconia sensor to produce any electrical signal
> > by means of a piezoelectric effect.
> >
> > Jay
> >
> >
> > _______________________________________________
> > Diy_efi mailing list
> > Diy_efi at diy-efi.org
> > http://www.diy-efi.org/mailman/listinfo/diy_efi
> >
>
>_______________________________________________
>Diy_efi mailing list
>Diy_efi at diy-efi.org
>http://www.diy-efi.org/mailman/listinfo/diy_efi


_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi