C'mon Shawn, have a little resourcefulness... ;-)

If you look at datasheets for a variety of physically similar devices,
you'll see that they all have specs in the same basic range for
capacitance and resonant frequency. This is basic physics, they're all
made from the same materials using the same basic process. You can
always find the resonant frequency by driving the piezo element with an
external signal generator and listen for the loudest frequency. You can
also measure it by putting a small resistor in series with the piezo
and look for the largest voltage drop across the piezo element -- this
will be it's resonant frequency.

It really doesn't take very long to characterize a given piezo element,
even if there are no markings on it at all.

Matt Pobursky
Maximum Performance Systems

On Wed, 16 Jun 2004 11:10:51 -0700, Shawn Wilton wrote:
> But you have to know the manufacturer to begin with.  All the ones I
> picked up were from surplus and there's no indication of manu.
>
> Matt Pobursky wrote:
>
> > On Wed, 16 Jun 2004 09:12:57 -0700, Shawn Wilton wrote:
> >
> >>Don't forget these need a lot of voltage.  I have a bunch of the 3 lead
> >>kind and you can run it with one lead, but you get low-moderate noise at
> >>20 volts.
> >
> >
> > You can greatly augment the acoustic output of piezo devices by edge
> > mounting them (this keeps mechanical damping to a minimum). Most piezo
> > manufacturers sell PCB mounting clips that hold them by the edges and
> > provide electrical contact especially for this purpose.
> >
> > You can also greatly increase the acoustic output by mounting the piezo
> > element in a tuned (resonant) enclosure. This is why many piezo buzzers
> > are sold in plastic cases. The case itself holds the piezo element by
> > it's edge in an enclosure tuned to it's resonant frequency.
> >
> > I wouldn't consider myself a piezo buzzer expert, but I've used almost
> > every type I have seen in dozens of applications over the past 25
> > years. Most of this information is available from the manufacturers
> > directly.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics