If I have several piezoeletric disc with a resonant (thickness) frequency of 125 kHz and stack them on top of each other, the overall resonant frequency seems to drop (but their individual resonant frequency ought to remain the same.)
So, the question: If want to achieve a lower working, i.e., use them at a lower frequency than their individual resonant frequency - is it than a good way/good practice to stack them? Or, is there a better way? (of course best would be to buy one with the right resonant frequency - but, I'm on a low (i.e., no)) budget here.)
Allt the best!