Abstract: Apparatus for monitoring the motion of a movable element, such as a rotatable shaft, comprising sensor means for producing a series of repetitive pulses in response to the motion of the movable element, ramp generator means for producing an increasing ramp signal, the ramp generator means including means for resetting the ramp signal to a starting level in response to each of the pulses, level detector means operable in response to the increase of the ramp signal above a predetermined level, and control means for performing a control function in response to the operation of the level detector means.

Abstract: A vibratory system is provided on a wall member of a receptacle. The vibratory system comprises inner and outer rod elements projecting transversely from the inner and outer sides of the wall member and secured thereto, as by an internal screw stud with the axes of the rod members substantially aligned. Vibrations are induced in the outer rod element by an electromagnet having a coil which is supplied with low frequency electrical pulses. The magnitude of such vibrations is sensed by sensing the electrical signals induced in the coil due to such vibrations. A biasing magnetic flux is produced between the electromagnet and the outer rod element so that the vibrations produce variations in the magnetic flux. The electrical pulses supplied to the coil are at a substantially lower frequency than the natural vibration frequency of the outer rod element.