US3710248A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measurements with digital voltmeters
Assignee: Gemalto Terminals Ltd
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Filing: 1970-09-23
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Granted: 1973-01-09
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Expires: 1990-09-23
Abstract
Abstract A digital voltmeter is adapted for measuring resistance by switching an internal reference voltage to the voltmeter input and switching the feedback resistor out of circuit. The unknown resistor is connected in place thereof. For measuring current the input resistor is removed from the input circuit.
Inventors
- 👤 J Bloomfield
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:11
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/25; G01R19/255; H; H03; H03M; H03M1/00; H03M1/12; H03M1/50
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
189 words
A digital meter for selectively measuring voltage and resistance comprising a summing circuit, an input circuit to which an input voltage to be measured can be applied, said input circuit including a first resistor, the input circuit being connected to feed current resulting from said voltage into said summing circuit through said first resistor to cause the output of said summing circuit to ramp away from a datum level, a control circuit, circuit means connected between said control circuit and said summing circuit and including a second resistor, said control being responsive to said output of said summing circuit to feed a second current into said summing circuit through said second resistor in said circuit means in opposition to the first said current to drive said output toward said datum level, means in said control circuit for providing a digital measure of said second current, an internal voltage reference, terminals connectable to an unknown resistor, and switching means operable to a resistance measurement setting for connecting said voltage reference to said input circuit, disconnecting saiD second resistor and connecting said terminals in place thereof when operated to said setting.
Claim 2
Dependent Claim
189 words
A digital meter for selectively measuring voltage and resistance comprising a summing circuit, an input circuit to which an input voltage to be measured can be applied, said input circuit including a first resistor, the input circuit being connected to feed current resulting from said voltage into said summing circuit through said first resistor to cause the output of said summing circuit to ramp away from a datum level, a control circuit, circuit means connected between said control circuit and said summing circuit and including a second resistor, said control being responsive to said output of said summing circuit to feed a second current into said summing circuit through said second resistor in said circuit means in opposition to the first said current to drive said output toward said datum level, means in said control circuit for providing a digital measure of said second current, an internal voltage reference, terminals connectable to an unknown resistor, and switching means operable to a resistance measurement setting for connecting said voltage reference to said input circuit, disconnecting saiD second resistor and connecting said terminals in place thereof when operated to said setting.
Claim 3
Dependent Claim
205 words
A digital meter for selectively measuring voltage and resistance comprising a summing circuit, an input circuit to which an input voltage to be measured can be applied, said input circuit including a first resistor, the input circuit being connected to feed current resulting from said voltage into said summing circuit through said first resistor to cause the output of said summing circuit to ramp away from a datum level, a control circuit, circuit means connected between said control circuit and said summing circuit and including a second resistor, said control circuit being responsive to said output of said summing circuit to feed a second current into said summing circuit through said second resistor in said circuit means in opposition to the first said current to drive said output toward said datum level, means in said control circuit for providing a digital measure of said second current, an internal voltage reference, terminals connectable to an unknown resistor, at least one standard resistor, and switching means operable to a resistance measurement setting for connecting said voltage reference to said input circuit, switching said standard resistor in place of said first resistor, disconnecting said second resistor and connecting said terminals in place thereof when operated to said setting.
Claim 4
Dependent Claim
205 words
A digital meter for selectively measuring voltage and resistance comprising a summing circuit, an input circuit to which an input voltage to be measured can be applied, said input circuit including a first resistor, the input circuit being connected to feed current resulting from said voltage into said summing circuit through said first resistor to cause the output of said summing circuit to ramp away from a datum level, a control circuit, circuit means connected between said control circuit and said summing circuit and including a second resistor, said control circuit being responsive to said output of said summing circuit to feed a second current into said summing circuit through said second resistor in said circuit means in opposition to the first said current to drive said output toward said datum level, means in said control circuit for providing a digital measure of said second current, an internal voltage reference, terminals connectable to an unknown resistor, at least one standard resistor, and switching means operable to a resistance measurement setting for connecting said voltage reference to said input circuit, switching said standard resistor in place of said first resistor, disconnecting said second resistor and connecting said terminals in place thereof when operated to said setting.
Claim 5
Dependent Claim
14 words
A digital meter according to claim 2, comprising means for selecting different standard resistors.
Claim 6
Dependent Claim
22 words
A meter according to claim 1 wherein said input circuit includes means for shunting said first resistor to permit measurement of current.
References Cited (Backward Citations)
US3051939A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-09 | 1976-07-10 | 1977-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-09 | 1980-07-10 | 1981-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-09 | 1984-07-10 | 1985-01-09 | $7700.00 | Window Closed / Lapsed |