US3612993A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedance measuring apparatus
Assignee: Applied Automation Inc
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Filing: 1970-06-11
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Granted: 1971-10-12
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Expires: 1990-06-11
Abstract
Abstract An unknown impedance is measured by means of an operational amplifier in which the unknown impedance and a reference impedance are connected in the feedback path selectively. A first calibrated resistance element is connected in the amplifier input circuit. A function generator having two outputs is connected to the amplifier and a second calibrated resistance element. The potential across the second resistance element is compared with the amplifier output.
Inventors
- 👤 Harold A Tims
- 👤 Joe P Lindsey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:21
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
158 words
Impedance measuring apparatus comprising: an amplifier having an input and an output; first switching means to connect a reference impedance element and a test impedance element selectively between the output and the input of said amplifier; a function generator having first and second outputs, said function generator providing alternating current signals at said first and second outputs, and including means to vary the phase of the signal at one of the outputs relative to the phase of the signal at the other output; a first calibrated adjustable resistor connected between the first output of said function generator and the input of said amplifier; a second calibrated adjustable resistor mechanically connected to said first resistor so that the two resistors have common resistance; second switching means to apply the first and second outputs of said function generator selectively across said second resistor; and adjustable means to compare the voltage across said second resistor with the output of said amplifier.
Claim 2
Dependent Claim
158 words
Impedance measuring apparatus comprising: an amplifier having an input and an output; first switching means to connect a reference impedance element and a test impedance element selectively between the output and the input of said amplifier; a function generator having first and second outputs, said function generator providing alternating current signals at said first and second outputs, and including means to vary the phase of the signal at one of the outputs relative to the phase of the signal at the other output; a first calibrated adjustable resistor connected between the first output of said function generator and the input of said amplifier; a second calibrated adjustable resistor mechanically connected to said first resistor so that the two resistors have common resistance; second switching means to apply the first and second outputs of said function generator selectively across said second resistor; and adjustable means to compare the voltage across said second resistor with the output of said amplifier.
Claim 3
Dependent Claim
45 words
The apparatus of claim 1 wherein said means to compare comprises a potentiometer having one end terminal connected to the output of said amplifier and the second end terminal connected to said second switching means, and a meter connected to the contactor of said potentiometer.
Claim 4
Dependent Claim
24 words
The apparatus of claim 2, further comprising a second amplifier and a band-pass filter connected between the contactor of said potentiometer and said meter.
Claim 5
Dependent Claim
11 words
The apparatus of claim 3 wherein said meter is an oscilloscope.
Claim 6
Dependent Claim
51 words
The apparatus of claim 1, further comprising a phase meter to measure the difference in phase between two alternating current signals of common frequency, said phase meter having first and second inputs, and means connecting said first and second inputs to the first and second outputs of said function generator, respectively.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-11 | 1975-04-12 | 1975-10-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-11 | 1979-04-12 | 1979-10-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-11 | 1983-04-12 | 1983-10-12 | $7700.00 | Window Closed / Lapsed |