OSCILLATOR AND OSCILLATOR CONTROL CIRCUIT

• US 3,629,726 A
• Filed: 08/29/1969
• Issued: 12/21/1971
• Est. Priority Date: 08/29/1969
• Status: Expired due to Term

• Current Assignee: Gabriel Popescu
• Original Assignee: Gabriel Popescu
• Inventors: Popescu, Gabriel
• Application Number:
  US04/854,240
• Time in Patent Office: 844 Days
• US Class Current: 331/116.00M
• CPC Class Codes: B06B 1/0253 taken directly from the generator circuit
• CPC Class Codes: B06B 2201/58 Magnetostrictive transducer
• CPC Class Codes: H03B 2200/0006 Clapp oscillator
• CPC Class Codes: H03B 5/30 with frequency-determining element being electromechanical resonator
• CPC Class Codes: H03B 5/362 the amplifier being a single transistor H03B5/364 - H03B5/368 take precedence

Abstract

An oscillator circuit adapted particularly for use with transducers for producing energy in the ultrasonic frequency range in which a combination of feedback signals representative of the voltage across the transducer and the current through the transducer are used to more precisely lock the oscillator to the resonant frequency of the load to thereby provide improved power transfer from the oscillator to the transducer. A current control circuit is also provided to control the amount of shock delivered by the transducer.

Claims

1. In combination an ultrasonic transducer means whose impedance varies as a function of its loading, oscillator circuit means including amplifying means having at least a control electrode and first and second output electrodes, means for connecting said transducer means in series between a point of reference potential and said first output electrode so that the current through said amplifying means is proportional to the current through said transducer means and a first voltage appears between said first output electrode and said point of reference potential which is proportional to the voltage across said transducer, and means connected to said second output electrode for producing a second voltage proportional to the current through said amplifying means and for applying said second voltage between said control electrode and said point of reference potential so that said first and second voltages are vectorially additive with respect to the operation of said amplifying means.

2. In the combination of claim 1 wherein said three electrode amplifying means is a semiconductor device having an emitter, a collector and a base electrode which are respectively said first and second output electrodes and said control electrode.

3. In the combination of claim 2 wherein said transducer is connected to said emitter electrode and said means for applying the second voltage to said base electrode comprises tuned feedback circuit means connected between the collector and base electrodes.

4. The combination of claim 1 wherein said means for producing said second voltage comprises a resistor means.

5. The combination of claim 2 wherein said means for producing said second voltage comprises resistor means connected between said collector electrode and a source of operating potential.

6. In the combination of claim 3 wherein said transducer is of the piezoelectric type and has the characteristics of a series circuit of inductance, capacitance and resistance.

7. In the combination of claim 1 further comprising means for supplying voltage to said oscillator amplifying means, control means for varying the magnitude of the supply voltage, and means responsive to the current through the transducer for operating said control means.

8. In the combination of claim 7 wherein said control means comprises a voltage comparator circuit, said current responsive means producing a voltage control signal which is proportional to the current through the transducer, and comparing means for setting a reference level voltage and for comparing the reference level voltage with the control voltage, said comparing means producing an output signal when the control voltage exceeds the reference level voltage.

9. In the combination of claim 8 further comprising a control device connected to said comparing means and to a power supply voltage, means connecting said control device as the power supply for the oscillator means, said control device responsive to the output signal of the comparing to vary the voltage from the voltage supplied to the oscillator means in a manner to attempt to maintain a substantially constant current through said transducer.

10. In the combination of claim 8 wherein said comparing means comprises a transistor with the reference level voltage being the inherent voltage drop between two electrodes of the transistor.

11. In the combination of claim 9 wherein said comparing means comprises a transistor with the reference level voltage being the inherent voltage drop between two electrodes of the transistor.