Using the circuit outlined in this white paper I have been able to find the anti-resonance of the piezo in question. I am using a Rigol DG1022 to create my signal, a sine wave at 20 V p-p, and a Yokogawa oscilloscope to look at my signal and measure the voltage over the R3 resistor. However, what I am having difficulty with is finding the resonance frequency. I believe what I need to do is use lower value resistors for R1 and R2 as the change in voltage around the resonance is to small for me to see.
It has been a few years since I have messed with electronics at all so I have a few questions.
1) What is it about the piezo being in a low impedance state that makes it so that the oscilloscope is not measuring the changes in voltage?
2)If I in fact do need lower resistance values for R1 and R2 in order to measure a voltage change at the resonance. How would I go about calculating what those values should be?