Abstract: A piezoelectric resonator (10) having a sacrificial mass-loading layer (16). Material is removed from the mass-loading layer (16) to raise a resonator frequency to a desired target. The sacrificial layer (16) is of a dense material, such as silver or gold, but is of such a relative thin layer that it can be used on high frequency aluminum electrodes (14) of a resonator (10) without increasing adverse spurious frequency problems. It is not necessary that the mass-loading layer (16) be conductive. In addition, the silver or gold sacrificial layer (16) can be removed by ion milling at practical and economical rates, unlike aluminum or aluminum oxide. Preferably, a diffusion barrier (18) is interposed between the electrodes (14) and the mass-loading layer (16).

Abstract: An impulse transducer that does not use eccentric, motor-driven weights is constructed of a permanent magnet movable armature that oscillates within a housing and impacts resilient bumpers to produce vibrations. The armature is accelerated by a varying magnetic field energized by an alternating current. The dimensions of the enclosed housing and the mass of the movable armature as well as the strength of the magnetic fields can be optimized for the impulse magnitude that is desired.