Transistor oscillator including ultrasonic generator crystal

Abstract

Abstract Ultrasonic oscillators having electronic transducers and excitation circuits for the transducers in which the transducers can be disconnected from the oscillator without causing damage. The excitation circuit comprises a primary and a secondary circuit, in which the primary circuit is adapted to be energized with AC and is provided with a rectifier therein for producing a source of pulsating DC for energizing the oscillator system. The primary circuit includes a transistor having a collector-emitter circuit connected through the primary winding of a transformer across the pulsating DC source and having its base connected to a voltage divider, also across the pulsating DC source, such that the transistor is biased nearly to cutoff. A feedback circuit is provided having a coil inductively coupled to the transformer primary and electrically connected to the transistor emitter and through a blocking capacitor to the transistor base. The primary winding and feedback coil are wound with numbers of turns to resonate at a frequency higher than the operating range of the transistor. A secondary circuit comprising a transformer secondary winding connected across the transducer is wound inductively coupled to the primary winding and to the feedback coil such that when introduced into the oscillator circuit physically or by closure of the transducer circuit connection thereto it tunes the oscillator to the resonant frequency of the transducer, which is within the operating range of the transistor. This provides for inherently making the oscillator operative when the secondary is introduced and making it quiescent, i.e., nonoscillatory, when the secondary circuit is removed physically or electrically.

Inventors

• 👤 Walter J Loria
• 👤 Jerome Suhre

Bibliographic Details