Piezo as a contact microphone

[Carel]

I would like to program a MCU to be able to detect water flowing through a pipe. The requirements are:

1.) No tapping into the piping system (it should be an external device only).
2.) It should use the principle of sound measuring (audio quality does not matter).
3.) It should only detect sound emitted from the object it is in contact with.

So - I was thinking of using a piezo from a buzzer. I need help in choosing the correct piezo, I am not sure whether I should be using an internal or external drive piezo. I want it to be very sensitive.

Are there any suggestions to what kind of piezo I should be looking for or specific parameters of the piezo I should be looking for?
I was looking at these, but I am so not sure whether I should take the Internal or External drive: http://za.rs-online.com/web/c/passi...o+buzzer#sort-by=P_breakPrice1&sort-order=asc

 

[73's de Edd]

.


Sir Carel . . . . . . .

" to detect water flowing through a pipe "

A that sensing point . . . . .would that be plastic -copper or galvanized iron or ? type of pipe ?

73's de Edd



.

 

[Carel]

It will probably be galvanized iron.

 

[elektrroda]

i don't know , whether that's is possible. Water is fluid where to spread sound. but from second side water when it flow , make a noise ( i mean as white noise) and this physical phenomena you can use . you must use filters who eliminate all noise about impulse character. Mic you use as sensor , and how will circuit to measure , control? if do you use digital circuit , you must write algorithm who will eliminate noise of impulse. place when will mount mic , you must protect material sound absorber. mic must touch pipe , you don't use glue .

 

[BobK]

Why not use a piezo contact microphone, which is designed for this purpose?

https://en.wikipedia.org/wiki/Contact_microphone

Bob

 

[elektrroda]

i thought about this converter piezoelectric . And I think that author of topic too

 

[Carel]

Why not use a piezo contact microphone, which is designed for this purpose?

https://en.wikipedia.org/wiki/Contact_microphone

Bob

A Piezo contact microphone is exactly the same thing as a Piezo buzzer. It refers to the same device, just used for a different purpose. I already know I want to use a Piezo as a microphone, but my original question is how to choose the correct one. This component is not just a standard device, there are different types of discs with Piezo material on them.

My question is however, should I use a Internal or External drive Piezo? Should I use a Piezo buzzer disc with a higher or lower audio volume level, in dB (this rating refers to sound emission - but remember I want to use it as a microphone)? There are many types of Piezo's. I would like to know for what parameters to look for to choose the best Piezo element?

 

[Colin Mitchell]

Buy a $2.00 music card from a $2.00 shop It contains a very sensitive contact microphone.

 

[elektrroda]

i don't know whether don't must use preamp. piezo has voltage to max 0,2 V. if author want hear a noise , he must use amplifier with limiter and filter high band , , must eliminate trouble of impulse

 

[BobK]

A Piezo contact microphone is exactly the same thing as a Piezo buzzer. It refers to the same device, just used for a different purpose. I already know I want to use a Piezo as a microphone, but my original question is how to choose the correct one. This component is not just a standard device, there are different types of discs with Piezo material on them.

My question is however, should I use a Internal or External drive Piezo? Should I use a Piezo buzzer disc with a higher or lower audio volume level, in dB (this rating refers to sound emission - but remember I want to use it as a microphone)? There are many types of Piezo's. I would like to know for what parameters to look for to choose the best Piezo element?

Yes, they are the same thing. But one is optimized for putting out sound, and the other for picking it up.

A dynamic microphone and a 12 in woofer are also the same thing, but I would not use the 12 in woofer to record my voice nor the dynamic microphone to blast the car next to mine with thundering bass.

Bob

 

[Carel]

A Piezo contact microphone is exactly the same thing as a Piezo buzzer. It refers to the same device, just used for a different purpose. I already know I want to use a Piezo as a microphone, but my original question is how to choose the correct one. This component is not just a standard device, there are different types of discs with Piezo material on them.

My question is however, should I use a Internal or External drive Piezo? Should I use a Piezo buzzer disc with a higher or lower audio volume level, in dB (this rating refers to sound emission - but remember I want to use it as a microphone)? There are many types of Piezo's. I would like to know for what parameters to look for to choose the best Piezo element?

Yes, they are the same thing. But one is optimized for putting out sound, and the other for picking it up.

A dynamic microphone and a 12 in woofer are also the same thing, but I would not use the 12 in woofer to record my voice nor the dynamic microphone to blast the car next to mine with thundering bass.

Bob

Yes - but that's my question. How to choose the "optimal Piezo". I have searched on RS's website, and they don't list the Piezo's under contact microphones, they list it as a buzzer. So, obviously I need to choose the right Piezo to make a good microphone. This is what I need help on. How do I choose the correct one?

For a dynamic microphone, there is lots of info out there with minimal use of Google. But for Piezo's - someone like me who have never used them as a mic before, I certainly need advise on how to choose one. At this stage, amplification is no problem. Filtering ain't no problem either. For my project, accuracy is what matters. And defining accuracy for my project would mean I want to detect the loudness of a sound (between 1 to 4 kHz) with a very high precision. As you know, water emits a sound at this frequency when passing through a pipe, but the vibration it causes are way too small to be even felt by hand (in my case). So, I need help on choosing the right Piezo that has the highest sensitivity that will generate the largest output voltage.

Like I said, Google is not to friendly regarding this.

 

[BobK]

And I am saying that a clue that a particular piezo is good as a contact microphone, is that is is sold as a contact microphone.

Bob