Piezo disk transducer

Guest
Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.

Thanks

Steve
 
steveahart@gmail.com wrote in
news:1175393904.182577.191140@y66g2000hsf.googlegroups.com:

Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.
Click to expand...
Resonance of a diaphragm is more a physical thing than electronic. If you
can get it mounted in your intended case, assembled and filled as close to
final result as you can easily get, you can test it.

Two ways: One is to put a microphone close to it, wrap the head of the mic
in a sock to damp all but the most immediate and direct signal path, then
send a slow square wave with sharp edges into the sounder, record the
microphone signal at the best sample rate you can get, and examine the
overshoot of the waveform. The square won't make it through a DC blocker,
but the overshoots will. Use plenty of mic gain, and avoid live feedback.

Second way is esier but has more room for error, sweep the frequency of a
sine wave with constant amplitude, and record the output as before, but
there's no need to be as careful with the mic placement, you're just
looking for peaks of higher amplitude. If you find a strong narrow one,
look closely at it (Spectrum analyser in Sound Forge or GoldWave or Cool
Edit) to get the frequency.
 
steveahart@gmail.com wrote in
news:1175393904.182577.191140@y66g2000hsf.googlegroups.com:

Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.
Click to expand...
Maybe an even simpler way, but you still need to mount it as intended, as
that will determine the frequency you'll get. When mounted, wire it
directly to an audio input and tap it gently with a light but hard object,
so that you're simulating a very short strong undamped pulse. Adjust the
gain for good level, then examine the response in the recorded waveform.
 
On 3/31/07 7:18 PM, in article
1175393904.182577.191140@y66g2000hsf.googlegroups.com,
"steveahart@gmail.com" <steveahart@gmail.com> wrote:

Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.

Thanks

Steve

What frequencies are you interested in. If you have an ac bridge that will
Click to expand...
work in the frequencies you are talking about, you can measure the impedance
at the frequencies of interest.

Also, try hitting the disk with an impulse and look at the response on an
oscilloscope. It should ring at the resonant frequency. It may be a bit
tricky to couple to it properly, but after all we cannot do it for you. You
also might have to use slightly different technique for series and parallel
resonances.

Bill
-- Fermez le Bush--about two years to go.
 
Put into a real circuit that does
somethin real ..

Input a tiny drive signal
and measure the DC amps
going into your driver ..

At around 50khz , you will see it absorb

very little power at its lowest harmonic .


---------------------------------------

Then buy a MFJ209 ( 2 -170MHZ RF Bridge )

and make a "dipper" and try same thing

on R.F. circuit components , and

get a fast electronics education .

Its the best way to "see" whats happening .


HAM RADIO magazine had an article
about changing RF bridge into a
grid Dip Oscillator ( "Dipper")

Its just a coil , resistor and Cap , that
makes MFJ209 read 3:1 SWR , over the
band /range .

I use mine handily ..
 
steveahart@gmail.com wrote:

Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.
Click to expand...
Metallize both sides if they aren't already. Conductive spray might
work. Then place a resistor in series (1k or so to ground), hook a scope
across that resistor and sweep it through with a generator.

--
Regards, Joerg

http://www.analogconsultants.com
 
Salmon Egg wrote:
On 3/31/07 7:18 PM, in article
1175393904.182577.191140@y66g2000hsf.googlegroups.com,
"steveahart@gmail.com" <steveahart@gmail.com> wrote:


Is there any easy way to test the resonance on a piezo disc
transducer? I have a few and need to know the resonance before I use
them in a circuit.

Thanks

Steve


What frequencies are you interested in. If you have an ac bridge that will
work in the frequencies you are talking about, you can measure the impedance
at the frequencies of interest.

Also, try hitting the disk with an impulse and look at the response on an
oscilloscope. It should ring at the resonant frequency. It may be a bit
tricky to couple to it properly, but after all we cannot do it for you. You
also might have to use slightly different technique for series and parallel
resonances.

Bill
-- Fermez le Bush--about two years to go.


excellent idea!
Click to expand...

Marc
 
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