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Variable frequency ultrasonic generator with constant power output

  • US 5,276,376 A
  • Filed: 06/09/1992
  • Issued: 01/04/1994
  • Est. Priority Date: 06/09/1992
  • Status: Expired due to Term
First Claim
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1. A generator for driving an ultrasonic transducer comprising, in combination:

  • an output circuit including the ultrasonic transducer and a coupled load, the output circuit having a resonant frequency which is affected by the magnitude of the load presented to the ultrasonic transducer,a voltage controlled oscillator for driving the output circuit, the voltage controlled oscillator having a frequency variable within a predetermined limited range,a resonance follower having an input connected to the output circuit and being coupled to the voltage controlled oscillator for tuning the voltage controlled oscillator to the resonant frequency of the output circuit, the resonance follower including means for sweeping the voltage controlled oscillator through at least a part of the operating frequency range thereof until the resonance follower determines that the output circuit is oscillating at about the resonance frequency of the load,a power control circuit including a user settable power level control for setting a power demand signal, a wattmeter connected in the output circuit for producing a signal relating to the actual power delivered by the output circuit, and means for modulating the DC power supplied to the output circuit to cause the actual power to be at a level established by the demanded power, the output power setting means being effective across at least a part of the range of the voltage controlled oscillator for matching the delivered power to the demanded power over the range of frequencies at which the load can resonate.

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