Piezoelectric Experiment

[Mechatronics Eng]

Dear Sirs, I am a new registered member here, so pleased to be with you, a mechatronics engineer and would like to share with you electromechanics thoughts.

I am in dire need to do an experiment to measure sound frequency ( or dB ) generated from a piezoelectric sound generator transducer.

Thanks.

 

[Sceadwian]

You can start simply by hooking up the piezo element directly to an oscilloscope that has decent sensitivity. If you do not have a scope that has decent sensitivity then start by creating a simple operational amplifier circuit to boost the output from the piezo to something a scope you have can read. Without an oscilloscope you could possibly use a PC sound card for input as long as you're within the human audio range, although you would definitely require and operational amplifier circuit to feed a sound card a high enough signal to read.

 

[alec_t]

To detect the piezo generator frequency, if in the audio range, you could use a PC to generate an audio output of variable frequency and adjust the output to give a zero beat frequency.

 

[Mechatronics Eng]

You can start simply by hooking up the piezo element directly to an oscilloscope that has decent sensitivity. If you do not have a scope that has decent sensitivity then start by creating a simple operational amplifier circuit to boost the output from the piezo to something a scope you have can read. Without an oscilloscope you could possibly use a PC sound card for input as long as you're within the human audio range, although you would definitely require and operational amplifier circuit to feed a sound card a high enough signal to read.

Sceadwian, thank you for your explination.
- If I connect the sound piezoelectric transducer directly to the oscilloscope, how can I operate the the trnsducer without an external power supply!

Please, could you post the circuit diagram that contains Op Amp?

 

[Mechatronics Eng]

To detect the piezo generator frequency, if in the audio range, you could use a PC to generate an audio output of variable frequency and adjust the output to give a zero beat frequency.

Thank you alec. I need futher details on using the PC to generate audio output. Kindly, would you put an expressing block diagram? Thanks.

 

[Sceadwian]

If I connect the sound piezoelectric transducer directly to the oscilloscope, how can I operate the the trnsducer without an external power supply!

Well you can't, you said you were trying to measure the output from a transducer, you didn't say the transducer didn't already have a driver.

I need futher details on using the PC to generate audio output. Kindly, would you put an expressing block diagram? Thanks.

This is only applicable if the frequencies are in the human audio range, PC sound cards have a steep drop off of frequency response after 22khz making even a few khz higher attenuated so much as to be unusable.

Output from a sound card to a piezo transducer is as straight forward as you can get no block diagram needed, simply connect the ground and one signal line (left or right doesn't matter) directly to the two wires from the transducer.

You posts are woefully lacking in the specifics of the devices you're actually using and the eact types of readings you're trying to get. We can't provide more information until you go into a LOT more details about what specifically you're trying to do.

 

[alec_t]

Another way to measure the piezo output frequency, if in the audible range, is to record the output and then analyse its spectrum on a PC using software such as Audacity (freeware).

 

[Sceadwian]

If you want frequency analsys Audicity isn't that great, try Spectrum Lab, I've used it for years incredibly useful software.

 

[Mechatronics Eng]

Dear sirs,


I really appreciate your assistance and patience. Let me inform you specifically what I need, please see attached image. Thank you.

 

[alec_t]

If you are driving the piezo at 2kHz as shown then you know the frequency already! The sound spectrum will be the 2kHz fundamental plus harmonics. So what is it exactly that you want to measure?