short of being exposed to the rotor piezo assembly center hole 40 rather access to the control electrode 42 is had along a rectilinear control electrode access channel 47 the access channel 47 is cut out of the second piezo layer 38 extending along the center hole 40 from the top surface 38b of the second layer 38 to the control electrode 42 still another conductive plate 50 is attached to the bottom surface 37a of the first piezo layer 37 that is on the surface which makes contact with the upper facing surface 27 of the stator dielectric assembly 25 preferably this conductive plate 50 is fired to the piezo material to form a unitary laminated layer of the rotor piezo assembly 35 this conductive plate 50 sometimes referred to hereafter as rotor piezo ground electrode 50 serves the double function of capacitor rotor and piezo element ground electrode that surface of the rotor piezo ground electrode 50 which contacts the stator dielectric assembly 25 is polished to a finish conforming closely with the top of the dielectric washer 26 the rotor piezo ground electrode 50 is formed in a semicircular pattern as seen in the figures which conforms closely in shape and size to the stator electrode plate 32 directly above the rotor.