Abstract: Apparatus for monitoring mechanical vibrations in a component part of an operating machine such as a large electrical power generator includes an electric charge producing transducer, preferably a piezoelectric accelerometer, affixed to the component part of the machine to be monitored, and a charge converter network located within the machine but relatively remote from the transducer. The charge converter network accepts the signal from the transducer, in the form of electrical charge generated at a rate and magnitude representative of the mechanical vibrations, and converts the charge signal to a conventional electronic signal. The charge converter network includes a differential operational amplifier having a resistive-capacitive feedback network providing equal impedance values to a corresponding resistive-capacitive network at the noninverting input of the amplifier. The transducer output is applied between the differential input terminals of the amplifier.