US4473796A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Resistance and capacitance measuring device
Assignee: Lockheed Martin Tactical Systems Inc
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Filing: 1982-06-18
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Granted: 1984-09-25
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Expires: 2002-06-18
Abstract
Abstract This circuit measures both the resistance and the capacitance of the parallel RC circuit that is the equivalent of any substantially non-inductive two-port device. Thus, the circuit can measure any resistance, capacitance, RC network, or diode, including photovoltaic diodes. The invention uses an operational amplifier, an audio A.C. oscillator and a voltage measuring device such as a digital RMS voltmeter. The resulting apparatus is small, inexpensive, accurate, and easy to operate. The resistance is measured with the audio oscillator set for a low frequency (such as 70 Hz); the capacitance is measured when the audio oscillator is set at a high frequency (such as 20 KHz). The resultant values can either be calculated using simple formulas or can be displayed directly using an analog or digital circuit.
Inventors
- 👤 Donald B. Nankivil
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:16
CPC Classifications
G; G01; G01R; G01R27/00; G01R27/02; G01R27/26
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
250 words
An apparatus for providing a direct visual reading of the values of the resistance and capacitance of the parallel resistive/capacitive circuit equivalent to any substantially non-inductive two-port device, comprising: an a.c. oscillator referenced to ground; a first operational amplifier having an inverting input terminal coupled to the first port of said device (the second port of the device being coupled to ground), a non-inverting input terminal coupled to the output of the a.c. oscillator, and an output terminal; a known resistance and a known capacitance each coupled between the inverting and output terminals of said first amplifier; a first a.c. to d.c. converter having a first terminal coupled to the output terminal of said first amplifier; a second a.c. to d.c. converter having a first terminal coupled to the positive terminal of said first amplifier; a first divider having first and second input terminals coupled to output terminals of each of said two converters, respectively; an inverter having an input terminal coupled to an output terminal of the first divider; a multiplier; a second divider; a second amplifier having a first input coupled to an output of said inverter, and having an output coupled to a first terminal of the second divider and to a first terminal of the multiplier; and a d.c. voltmeter switchably coupled to an output of the second divider (in order to measure the resistance of the two-port device) and to an output of the multiplier (in order to measure the capacitance of the two-port device).
Claim 2
Independent Claim
250 words
An apparatus for providing a direct visual reading of the values of the resistance and capacitance of the parallel resistive/capacitive circuit equivalent to any substantially non-inductive two-port device, comprising: an a.c. oscillator referenced to ground; a first operational amplifier having an inverting input terminal coupled to the first port of said device (the second port of the device being coupled to ground), a non-inverting input terminal coupled to the output of the a.c. oscillator, and an output terminal; a known resistance and a known capacitance each coupled between the inverting and output terminals of said first amplifier; a first a.c. to d.c. converter having a first terminal coupled to the output terminal of said first amplifier; a second a.c. to d.c. converter having a first terminal coupled to the positive terminal of said first amplifier; a first divider having first and second input terminals coupled to output terminals of each of said two converters, respectively; an inverter having an input terminal coupled to an output terminal of the first divider; a multiplier; a second divider; a second amplifier having a first input coupled to an output of said inverter, and having an output coupled to a first terminal of the second divider and to a first terminal of the multiplier; and a d.c. voltmeter switchably coupled to an output of the second divider (in order to measure the resistance of the two-port device) and to an output of the multiplier (in order to measure the capacitance of the two-port device).
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-25 | 1988-03-26 | 1988-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-25 | 1992-03-26 | 1992-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-25 | 1996-03-26 | 1996-09-25 | $7700.00 | Window Closed / Lapsed |