The piezoelectric elements useful for detecting vibration or knocking. You can use them in a simple way by measuring the voltage at the output. Can also be used for very small sensors, audio such as a buzzer. Membrane with an outer diameter of 20 mm, bore 14 mm and a thickness of 0.20 mm. Andmpedancja is 1000 Ohms, the capacitance of 10 NF, the frequency...