Abstract: A swept sideband driver circuit has a boost converter followed by a buck converter obtaining near unity power factor. A full wave bridge powered from the buck converter circuit drives the PZT output load. The output of the buck converter circuit is controlled by a power level control circuit. The analog power level control circuit receives a sample of the output load current and a sample of the output load voltage from which it produces a product. The product signal is compared with manually adjusted pot signal. A difference signal results and used to adjust the output voltage of the buck converter circuit thereby increasing or decreasing the power to the load to drive the error signal to zero. A swept sideband modulation circuit modulates the frequency of the full wave bridge with a harmonic rich signal thereby imposing side bands on the voltage to the PZT load.

Abstract: A generator for driving an ultrasonic transducer for use in ultrasonic cleaning. The generator is capable of maintaining substantially constant real output to a load while the output frequency of the generator is square wave frequency modulated about a wide bandwidth. Thus, the generator is capable of maintaining substantially constant real output to the load even if the output frequency is modulated substantially away from the load's resonant frequency. The square wave modulation of the output frequency causes improved cavitation of semi-aqueous cleaning solutions used in the load, and thus improves the cleaning action of the ultrasonic transducer.