Patent US3872386A successfully refreshed from Google Patents.
US3872386A
Expired / Lapsed
US
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Test device
Assignee: Individual
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Filing: 1973-05-07
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Granted: 1975-03-18
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Expires: 1993-05-07
Abstract
Abstract The disclosure relates to a test instrument of compact size, operable with a battery source and capable of measuring with high precision voltages in the millivolt and low voltage ranges, milliamps, provide precision outputs in the millivolt and low voltage ranges, precision milliamps outputs and provide a two wire transmitter simulation. Measurements are made utilizing light emitting diode (LED) devices and operational amplifiers operating at high levels to minimize errors.
Inventors
- 👤 Gabriel J Luhowy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:47
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/165; G01R19/16533; G01R19/16538; G01R19/16542; G01R17/00; G01R17/20; G01R17/22; G01R19/14
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
152 words
A measuring system comprising in combination, a precision selectable first voltage, a differential operation amplifier having a pair of inputs and an output with one of said inputs connected to said first voltage, means coupled to the other of said inputs for providing an unknown input signal of a second voltage representing a predetermined condition, a pair of light emitting diodes normally in the same one of their on-off states, first voltage amplifying means coupled to said output and responsive to one of said polarities to change the state of one of the diodes, second voltage amplifying means coupled to said output and responsive to the other of said polarities to change the state of the other of said diodes and calibrating means for adjusting said first voltage to retain said diodes in the one of their on-off states, wherein the first and second means comprise driving transistors of opposite conductivity type.
Claim 2
Dependent Claim
152 words
A measuring system comprising in combination, a precision selectable first voltage, a differential operation amplifier having a pair of inputs and an output with one of said inputs connected to said first voltage, means coupled to the other of said inputs for providing an unknown input signal of a second voltage representing a predetermined condition, a pair of light emitting diodes normally in the same one of their on-off states, first voltage amplifying means coupled to said output and responsive to one of said polarities to change the state of one of the diodes, second voltage amplifying means coupled to said output and responsive to the other of said polarities to change the state of the other of said diodes and calibrating means for adjusting said first voltage to retain said diodes in the one of their on-off states, wherein the first and second means comprise driving transistors of opposite conductivity type.
Claim 3
Dependent Claim
23 words
A measuring system in accordance with claim 1 wherein the light emitting diodes are connected in the current path of a respective transistor.
Claim 4
Dependent Claim
17 words
A measuring system in accordance with claim 2 wherein said transistors are normally in a non-conductive state.
References Cited (Backward Citations)
US3076901A
Cited
US3228025A
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US3530378A
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US3530389A
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US3747006A
Cited
US3696304A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-17 | 1978-09-16 | 1979-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-17 | 1982-09-16 | 1983-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-17 | 1986-09-16 | 1987-03-18 | $7700.00 | Window Closed / Lapsed |