Diode-quad bridge circuit means

• US 3,869,676 A
• Filed: 04/22/1974
• Issued: 03/04/1975
• Est. Priority Date: 12/20/1971
• Status: Expired due to Term

• Current Assignee: Dean R. Harrison, John Dimeff
• Original Assignee: Dean R. Harrison, John Dimeff
• Inventors: Harrison, Dean R., Dimeff, John
• Primary Examiner(s): Brody, Alfred L.
• Application Number:
  US05/462,844
• Time in Patent Office: 316 Days
• Field of Search: 332/47 329/166,204 324/DIG.1 307/321
• US Class Current: 324/680
• CPC Class Codes: G01R 23/06 by converting frequency into an amplitude of current or voltage
• CPC Class Codes: G01R 27/16 Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
• CPC Class Codes: H03D 3/00 Demodulation of angle-, frequency- or phase- modulated oscillations H03D5/00, H03D9/00, H03D11/00 take precedence
• CPC Class Codes: H03D 3/26 by means of sloping amplitude/frequency characteristic of tuned or reactive circuit H03D3/28 - H03D3/32 takes precedence

Abstract

A transducer and frequency discriminator circuit including a four-terminal circulating diode bridge, a first pair of capacitors connected in series across two terminals of the bridge, and a second pair of capacitors, or other impedance elements, connected in series across the other two terminals of the bridge. A source of balanced alternating electrical energy for energizing the circuit is coupled between the commonly connected plates of the first pair of capacitors and the commonly connected plates of the second pair of capacitors. Due to the operation of the diode bridge, the sum of the resultant charges developed on the first pair of capacitors is proportional to the relationship between the respective capacitors of the second pair, and consequently, an output voltage taken across the first pair of capacitors will be proportional to that relationship.

Claims

1. A transducer circuit, comprising:

first and second input terminals;

a diode bridge including first, second, third and fourth bridge terminals consecutively coupled together by four diodes polarized in circulating relationship;

a signal source for developing a signal of balanced alternating polarity across said first and second input terminals;

a first capacitor coupling said first input terminal to said first bridge terminal, and a second capacitor coupling said first input terminal to said third bridge terminal; and

a first impedance means coupling said second bridge terminal to said second input terminal, and a second impedance means coupling said forth bridge terminal to said second input terminal, the impedance of at least one of said first and second impedance means being variable, and the impedances of each of said first and second capacitors being small with respect to the impedances of each of said first and second impedance means at the frequency of said signal source, whereby an output signal developed across said first and third bridge terminals is proportional to the difference between the impedances of said first impedance means and said second impedance means divided by the sum of the impedances of said first impedance means and said second impedance means.

2. A transducer circuit as recited in claim 1 wherein said first impedance means includes a fixed capacitor, and said second impedance means includes a variable capacitor.

3. A transducer circuit as recited in claim 2 wherein said first impedance means further includes a first inductor in series with said fixed capacitor, and said second impedance means further includes a second inductor in series with said variable capacitor.

4. A transducer circuit as recited in claim 2 wherein said first impedance means further includes a first inductor in parallel with said fixed capacitor, and said second impedance means further includes a second inductor in parallel with said variable capacitOr.

5. A transducer circuit as recited in claim 1 wherein said first impedance means includes a fixed resistor, and said second impedance means includes a variable resistor.

6. A transducer circuit as recited in claim 1 wherein said first impedane means includes a fixed inductor, and said second impedance means includes a variable inductor.

7. A transducer circuit as recited in claim 1 and further comprising:

a first output terminal and a second output terminal;

a third impedance means coupling said first bridge terminal to said first output terminal;

a fourth impedance means coupling said third bridge terminal to said second output terminal; and

a third capacitor coupling said first output terminal to said second output terminal.

8. A transducer circuit, comprising:

first and second output terminals;

a first capacitor and a second capacitor forming a first series circuit coupling said first output terminal to said second output terminal;

a first diode and a second diode polarized in a first common direction and forming a second series circuit coupling said first output terminal to said second output terminal;

a third diode and a fourth diode polarized in a second common direction and forming a third series circuit coupling said first output terminal to said second output terminal;

a first impedance means and a second impedance means forming a fourth series circuit coupling the circuit junction between said first and second diodes to the circuit junction between said third and fourth diodes; and

a source of alternating current coupling the circuit junction between said first and second capacitors to the circuit junction between said first and second impedance means, whereby an output signal developed across said first and second output terminals is proportional to the difference between the impedances of said first impedance means and said second impedance means divided by the sum of the impedances of said first impedance means and said second impedance means.

9. A transducer circuit as recited in claim 7 wherein said first output terminal is connected to said first and second series circuits by a first resistor, said second output terminal is connected to said first and second series circuits by a second resistor, and said first output terminal is capacitively coupled to said second output terminal.

10. A transducer circuit, comprising:

a first output terminal and a second output terminal;

first, second and third series circuits coupled in parallel between said first and second output terminals, said first series circuit including first and second capacitors coupled together at a first circuit junction, said second series circuit including first and second diodes coupled together at a second circuit junction and polarized in a first common direction, and said third series circuit including third and fourth diodes coupled together at a third circuit junction and polarized in a second common direction;

a first impedance means and a second impedance means coupled together at a fourth circuit junction and forming a fourth series circuit coupling said second circuit junction to said third circuit junction; and

a source of alternating current coupling said first circuit junction to said fourth circuit junction, whereby an output signal developed across said first and second output terminals is proportional to the difference between the impedances of said first impedance means and said second impedance means divided by the sum of the impedances of said first impedance means and said second impedance means.

11. A transducer circuit as recited in claim 10 wherein said first impedance means and said second impedance means have different impedance characteristics.