Abstract: An ultrasonic electro-mechanical resonant system and instrument that provides improvements in the design and implementation of a feedback system. The disclosed configuration and orientation of coils enhance the motional or velocity feedback signals while minimizing the effects of transformer coupling. A two coil and a three coil approach is disclosed that takes advantage of non-homogeneous magnetic fields. An asymmetrical arrangement enables velocity signals to be coupled into the coils without requiring additional signal conditioning or capacitive elements.