The circuit shown in the figure can be used to detect vibrations or to provide amplified acoustic signals, captured by a piezoelectric transducer. In this circuit we also use the operational amplifier LM108 whose characteristics were described in the CIR4564 project. The gain of the circuit basically depends on R3 which can be changed according to the application and the characteristics of the used transducer. The power supply does not have to be symmetrical. Resistors R1 and R2 form a reference divider for the polarization of the non-inverting input. Other resistor values provided they are the same can be tested.
