I have a self drive piezo element/self excited piezo element that I want to resonate at about 1-2kHz. As of my understanding, by using a circuit like in the figure below, the element will resonate at its eigenfrequency (the frequency with the most SPL). However, my piezo element's eigenfrequency seems to be about 17kHz. How can I create a circuit for controlling the resonating frequency? I guess it can be done by supplying a PWM signal in addition with an op-amp or something like that, but I am not quite sure how to do it.
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eidetech
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A piezo has one strong resonant frequency and a few weaker resonances. The physical parts of the piezo determine the resonant frequency plus its physical enclosure measurements. You cannot change a 17kHz piezo to resonate at 2kHz. – Audioguru Jun 13 '23 at 13:07
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Hmm yeah I agree. I have a PCB that makes the piezo oscillate at about 1.4kHz at a very audible volume. When I use the circuit in the figure above, and use my phone with an audio spectrum app, I can clearly see that it resonates at about 17kHz. The problem is that the components on the PCB that makes it oscillate at about 1.4kHz are not labeled, so it is very hard to reverse engineer it. – eidetech Jun 13 '23 at 13:17
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There are many different types of oscillators, I do not know which one you want.
Here is the horrible frequency response of a typical piezo transducer (speaker).
The difference in output level between the resonant peaks and the lower nulls is huge (40dB):
Audioguru
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