Transduction, control and measurement of vibration in vibratory apparatus

Claim 1

Apparatus for controlling the amplitude of vibration of an electrically driven mechanical vibratory device; a field effect transistor; an accelerometer adapted to be mounted and oriented on the device to produce a first electrical potential varying as the acceleration in the direction of vibration of the device, the accelerometer being connected to apply the electrical output of the potential thereof between the gate and the emitter of the field effect transistor; means for applying a second potential between the collector and the emitter of the field effect transistor, of a magnitude to maintain conduction therein for the range of said output; means for producing a third potential proportional to the collector-emitter current flow through the field effect transistor; means for amplifying the electrical output of the third potential producing means; and means inversely responsive to the amplitude of the alternatingcurrent component of the third potential for controlling the current applied to drive the device, in which the accelerometer includes an oscillatory mounting shaft and is encapsulated for mounting on the device, the mounting shaft being encased in resilient material.