Abstract: A piezo electric transducer employs a stack of piezo electric crystals interposed between electrodes and maintained under compression to develop an electrical charge which instantaneously corresponds to the acceleration of the device. One or two electrical resistors in series with the piezo electric crystal stack output develops a charge which instantaneously corresponds to the velocity of the device. The velocity responsive charge is delivered to a charge converter which may be located remotely from the piezo electric transducer. The charge converter generates an electrical signal having a voltage which is proportional to the instantaneous velocity of the device. The assembly permits use of high-sensitivity piezo electric crystals.

Abstract: An electromechanical transducer employs an Eddy current type displacement sensing device mounted in confronting relation to a seismically supported, nonmagnetic metal beam which is presented within an enclosed chamber. Movement of the nonmagnetic metal beam is damped. Movement of the nonmagnetic metal beam relative to the Eddy current type displacement sensing device occurs when the device is moving cyclically at low frequencies up to about 200 Hertz. Because of the damping of the movement of the metal beam, its instantaneous displacement is proportional to the instantaneous acceleration applied to the transducer. The output electrical signal from the Eddy current displacement sensing device can be integrated to provide an output signal directly proportional to the instantaneous velocity of the transducer. The signal can be twice integrated to provide an output signal corresponding to the instantaneous displacement of the transducer.