US3636440A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Isolation-guarding measuring instrument for in-circuit component testing
Assignee: GLENVILLE GAGE Co Inc
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Filing: 1970-05-27
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Granted: 1972-01-18
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Expires: 1990-05-27
Abstract
Abstract A portable, isolation-guarding measuring instrument that may be easily carried by electronic technicians, television service repairmen, etc. The instrument comprises a suitable meter movement of the voltmeter-type for providing an indication of the magnitude of an electrical signal and having first and second input measurement terminal leads for coupling the opposite terminals of an in-circuit component to be measured to the meter movement and to an excitation signal. A third isolation-guarding terminal lead maintained at essentially the same potential as the potential of one of the first and second input measurement terminal leads, is provided for connection to nodal points of other circuit components connected in parallel circuit relationship with the in-circuit component to be measured. As a result, measurement of the actual value of the in-circuit component can be obtained without requiring that the in-circuit component be disconnected even partially from the other components with which it is in circuit relationship.
Inventors
- 👤 Melvin E Stanford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 15:22
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/2832; G01R31/2836; G01R31/2843
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
247 words
A portable guarding instrument for measuring the in-circuit impedance of a circuit component connected to as least one other circuit component in a circuit having at least three junction nodal points comprising, in combination feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and adapted for connection to a source of excitation signals, meter means for providing an indication of an electrical signal connected between the output of the amplifier means and a source of ground potential, first and second input measurement lead means for coupling to nodal points formed by the opposite terminals of a component under test, said first lead means adapted for connection to a source of excitation signals and said second lead means connected to said amplifier, and third isolation guarding lead means for coupling to remaining junction nodal points of other components connected in circuit relationship with the component under test, said third lead means being connected to a source of potential maintained at the potential of one of said first or second lead means whichever is at the virtual ground potential of the feedback amplifier input whereby essentially zero potential is maintained across other in-circuit components not being tested as a result of the third isolation guarding lead connection thereby to provide a measurement of the actual value of the in-circuit component being tested without requiring that the in-circuit component be disconnected even partially from the other components with which it is in circuit relationship.
Claim 2
Dependent Claim
247 words
A portable guarding instrument for measuring the in-circuit impedance of a circuit component connected to as least one other circuit component in a circuit having at least three junction nodal points comprising, in combination feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and adapted for connection to a source of excitation signals, meter means for providing an indication of an electrical signal connected between the output of the amplifier means and a source of ground potential, first and second input measurement lead means for coupling to nodal points formed by the opposite terminals of a component under test, said first lead means adapted for connection to a source of excitation signals and said second lead means connected to said amplifier, and third isolation guarding lead means for coupling to remaining junction nodal points of other components connected in circuit relationship with the component under test, said third lead means being connected to a source of potential maintained at the potential of one of said first or second lead means whichever is at the virtual ground potential of the feedback amplifier input whereby essentially zero potential is maintained across other in-circuit components not being tested as a result of the third isolation guarding lead connection thereby to provide a measurement of the actual value of the in-circuit component being tested without requiring that the in-circuit component be disconnected even partially from the other components with which it is in circuit relationship.
Claim 3
Dependent Claim
83 words
An isolation-guarding measuring instrument according to claim 1 wherein the third isolation-guarding lead means is maintained essentially at the potential of the first input measurement lead means, the first lead means is connected to the input of the feedback amplifier means and is maintained at virtual ground potential, and the second input measurement lead means is connected to the output of the feedback amplifier means whereby the in-circuit component to be measured is connected in the feedback path of the feedback amplifier means.
Claim 4
Dependent Claim
55 words
An isolation-guarding measuring instrument according to claim 2 wherein the source of excitation signal comprises means for supplying an input current of known value to the input of the feedback amplifier means and the output of the feedback amplifier means is proportional to the value of the feedback impedance of the in-circuit component being measured.
Claim 5
Dependent Claim
64 words
An isolation-guarding measuring instrument according to claim 3 wherein the means for supplying an input current of known value to the input of the feedback amplifier means comprises a matrix of calibrating resistors of known differing values and selector switch means for connecting desired ones of the calibrating resistors in circuit relationship with a source excitation signal and the input of the amplifier means.
Claim 6
Dependent Claim
52 words
An isolation-guarding measuring instrument according to claim 4 further including input potential adjusting variable resistor means coupled to the input of the feeDback amplifier means for initially adjusting the potential of the feedback amplifier means input to a value of virtual ground potential prior to a measurement being taken with the instrument.
Claim 7
Dependent Claim
49 words
An isolation-guarding measuring instrument according to claim 5 further including a second input signal current full scale adjust variable resistor means coupled to the matrix of calibrating resistors for initially adjusting the full scale value of the input signal current supplied to the input of the feedback amplifier means.
Claim 8
Dependent Claim
54 words
An isolation-guarding measuring instrument according to claim 6 further including first transistor emitter-follower amplifier means interconnected between the output of the second input signal current full scale adjust variable resistor means and matrix of calibrating resistors and second transistor emitter-follower amplifier means interconnected between the output of the amplifier means and the meter means.
Claim 9
Dependent Claim
30 words
An isolation-guarding measuring instrument according to claim 7 further including a multiplicity of terminals on the third isolation-guarding terminal lead means for connection to a multiplicity of junction nodal points.
Claim 10
Dependent Claim
30 words
An isolation-guarding measuring instrument according to claim 1 further including a multiplicity of terminals on the third isolation-guarding terminal lead means for connection to a multiplicity of junction nodal points.
Claim 11
Dependent Claim
87 words
An isolation-guarding measuring instrument according to claim 1 wherein the third isolation-guarding lead means is maintained essentially at the potential of the second input measurement lead means, the second input measurement lead means is connected to the input of the feedback amplifier means and is maintained at virtual ground potential, and the first input measurement lead means is connected to a source excitation signal whereby excitation current is first supplied through the in-circuit component to be measured and thence to the input to the feedback amplifier means.
Claim 12
Dependent Claim
69 words
An isolation-guarding measuring instrument according to claim 10 further including means for adjusting the feedback current of the feedback amplifier means and an input current of known value is supplied to the input terminal of the feedback amplifier means and the adjusted value of the impedance in the feedback path of the feedback amplifier means is proportional to the value of the impedance of the in-circuit component being measured.
Claim 13
Dependent Claim
228 words
A portable guarding instrument for measuring the in-circuit impedance of a circuit component connected to at least one other circuit component in a circuit having at least three junction nodal points comprising in combination feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and an output, meter means coupled to the output of the feedback amplifier means for providing an indication of the value of the output signal from the feedback amplifier means, first and second input measurement lead means for coupling nodal points formed by the opposite terminals of an in-circuit component to be measured to the feedback amplifier means and to a source of excitation signal, and third isolation-guarding lead means connected to a source of potential maintained at essentially the same potential as the potential of one of said first and second input measurement lead means whichever is maintained at virtual ground potential, said third lead means being applied to remaining nodal points of other circuit components coupled in parallel circuit relationship with the in-circuit component to be measured whereby essentially zero potential difference is maintained across other in-circuit components not being tested and measurement of the actual value of the in-circuit component being tested can be obtained without requiring that the in-circuit component be disconnected even partially from the other components with which it is in circuit relationship.
Claim 14
Dependent Claim
228 words
A portable guarding instrument for measuring the in-circuit impedance of a circuit component connected to at least one other circuit component in a circuit having at least three junction nodal points comprising in combination feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and an output, meter means coupled to the output of the feedback amplifier means for providing an indication of the value of the output signal from the feedback amplifier means, first and second input measurement lead means for coupling nodal points formed by the opposite terminals of an in-circuit component to be measured to the feedback amplifier means and to a source of excitation signal, and third isolation-guarding lead means connected to a source of potential maintained at essentially the same potential as the potential of one of said first and second input measurement lead means whichever is maintained at virtual ground potential, said third lead means being applied to remaining nodal points of other circuit components coupled in parallel circuit relationship with the in-circuit component to be measured whereby essentially zero potential difference is maintained across other in-circuit components not being tested and measurement of the actual value of the in-circuit component being tested can be obtained without requiring that the in-circuit component be disconnected even partially from the other components with which it is in circuit relationship.
Claim 15
Dependent Claim
202 words
An isolation-guarding measuring instrument for measuring the value of an in-circuit Component of an electrical circuit under test at different points in an electrical circuit having at least one other junction nodal point coupled to it in circuit relationship, comprising feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and an output, meter means coupled to the output of the feedback amplifier means for providing an indication of the value of the output signal from the feedback amplifier means, first and second input measurement lead means for coupling nodal points of an in-circuit component to be measured to said feedback amplifier means, and isolation-guarding lead means connected to a source of potential maintained at essentially the same potential as one of said input measurement lead means whichever is maintained at virtual ground potential for coupling to other in-circuit junction nodal points connected in circuit relationship with the component to be tested whereby essentially zero potential difference is maintained between the component being tested and other in-circuit junction nodal points connected to said isolation-guarding lead means and the actual value of any given in-circuit component can be tested without requiring that the circuit under test be dismantled.
Claim 16
Dependent Claim
202 words
An isolation-guarding measuring instrument for measuring the value of an in-circuit Component of an electrical circuit under test at different points in an electrical circuit having at least one other junction nodal point coupled to it in circuit relationship, comprising feedback amplifier means having an input maintained at virtual ground potential through internal feedback circuitry and an output, meter means coupled to the output of the feedback amplifier means for providing an indication of the value of the output signal from the feedback amplifier means, first and second input measurement lead means for coupling nodal points of an in-circuit component to be measured to said feedback amplifier means, and isolation-guarding lead means connected to a source of potential maintained at essentially the same potential as one of said input measurement lead means whichever is maintained at virtual ground potential for coupling to other in-circuit junction nodal points connected in circuit relationship with the component to be tested whereby essentially zero potential difference is maintained between the component being tested and other in-circuit junction nodal points connected to said isolation-guarding lead means and the actual value of any given in-circuit component can be tested without requiring that the circuit under test be dismantled.
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) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |