A method of maintaining a constant movement of a cutting blade of an ultrasonic waveguide includes providing an ultrasonic transducer operable to convert a received motional current into a movement of a cutting blade of an ultrasonic waveguide, a measurement circuit connected in a parallel configuration with the ultrasonic transducer, and a variable power source operable to supply current through a set of connection points to the parallel configuration and thereby create the motional current in the ultrasonic transducer. Current is supplied through a set of connection points of the parallel configuration with the variable power source to, thereby, create the motional current in the ultrasonic transducer and the motional current is regulated with a current controller by varying an output of the power source, thereby maintaining a substantially constant rate of movement of the cutting blade across a variety of cutting loads.