Patent US3119457A successfully refreshed from Google Patents.
US3784906A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bridge having multiple nulls
Assignee: BIDDLE CO J
•
Filing: 1971-11-01
•
Granted: 1974-01-08
•
Expires: 1991-11-01
Abstract
Abstract A multiple null bridge has more than two parallel branches, all of the branches being divided into two series portions of predetermined resistance ratio, except the first branch which contains a known resistance and means for connecting an unknown resistance in series with the known resistance. High input impedance d.c. null-detecting amplifiers all have one input terminal connected between the known and unknown resistance in the first branch with the other input terminal of each amplifier being connected between the respective series portions of different ones of the other parallel branches. The amplifiers are of high input impedance type so that they will not load the voltage divider branches in off-null condition.
Inventors
- 👤 D Ironside
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:33
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/145; G01R17/00; G01R17/10; G01R17/105
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
189 words
In a Wheatstone bridge testing circuit adapted to employ a direct current power source across first and second parallel branches consisting of resistances in series, wherein one branch contains a known resistance and means for receiveing an unknown resistance to be tested and the other branch consists of series resistances of predetermined ratio, the improvement of connecting a first high input impedance direct current amplifier with one input terminal connected to said first branch between the known and unknown resistances and its other terminal connected to said second branch between the resistances of predetermined ratio and adding in parallel with the first and second branches at least a third branch similar to the first or second and a second high input impedance direct current amplifier with one terminal connected to said first branch at the same point of connection as the first amplifier and the other terminal connected to said third branch at a point corresponding to the point of connection in the second branch, whereby a multiple null bridge is formed permitting At least two simultaneous comparisons of known against unknown resistances with respect to separate null points.
Claim 2
Dependent Claim
189 words
In a Wheatstone bridge testing circuit adapted to employ a direct current power source across first and second parallel branches consisting of resistances in series, wherein one branch contains a known resistance and means for receiveing an unknown resistance to be tested and the other branch consists of series resistances of predetermined ratio, the improvement of connecting a first high input impedance direct current amplifier with one input terminal connected to said first branch between the known and unknown resistances and its other terminal connected to said second branch between the resistances of predetermined ratio and adding in parallel with the first and second branches at least a third branch similar to the first or second and a second high input impedance direct current amplifier with one terminal connected to said first branch at the same point of connection as the first amplifier and the other terminal connected to said third branch at a point corresponding to the point of connection in the second branch, whereby a multiple null bridge is formed permitting At least two simultaneous comparisons of known against unknown resistances with respect to separate null points.
Claim 3
Dependent Claim
81 words
The Wheatstone bridge testing circuit of claim 1 in which at least a fourth branch containing resistances in a third predetermined ratio is connected in parallel with the first, second and third branches and a third high input impedance direct current amplifier is connected across the first and fourth branches with one terminal connected to the same point of connection in said first branch and the other terminal connected to the fourth branch between said resistance of a third predetermined ratio.
Claim 4
Dependent Claim
80 words
The Wheatstone bridge testing circuit of claim 2 in which at least a fifth branch containing resistance in a fourth predetermined ratio is connected in parallel with the first, second, third and fourth branches and fourth high impedance direct current amplifier is connected across the first and fifth branches with one terminal connected to the same point of connection in said first branch and the other terminal connected to the fifth branch between said resistances of a fourth predetermined ratio.
Claim 5
Dependent Claim
32 words
The Wheatstone bridge of claim 1 in which at least one input to each high impedance direct current amplifier contains a current limiting impedance preventing overloading of the amplifier in non-null conditions.
Claim 6
Dependent Claim
16 words
The Wheatstone bridge of claim 1 in which the high input impedance amplifiers are FET amplifiers.
Claim 7
Dependent Claim
30 words
The Wheatsone bridge of claim 5 in which at least one input to each high impedance amplifier contains a current limiting impedance preventing overloading of the amplifier in non-null conditions.
Claim 8
Dependent Claim
63 words
The Wheatstone bridge testing circuit of claim 1 in which the unknown resistance is in the first branch and the second and third branches contain resistances of known predetermined ratios different from one another, the first and second amplifiers feed a logic circuit indicating whether an unknown resistor undergoing trimming is higher than both nulls, lower than both nulls or between the nulls.
Claim 9
Independent Claim
75 words
A method of trimming resistors to a resistance intermediate the respective null points of a dual null direct current Wheatstone bridge comprising placing a resistor to be trimmed to a resistance between the two nulls in said dual null Wheatstone bridge as an unknown resistance, adjusting the resistance while it is in said bridge, and observing the change of resistance and ceasing adjustment when its resistance passes one null and lies between the two nulls.
Claim 10
Independent Claim
75 words
A method of trimming resistors to a resistance intermediate the respective null points of a dual null direct current Wheatstone bridge comprising placing a resistor to be trimmed to a resistance between the two nulls in said dual null Wheatstone bridge as an unknown resistance, adjusting the resistance while it is in said bridge, and observing the change of resistance and ceasing adjustment when its resistance passes one null and lies between the two nulls.
Claim 11
Independent Claim
64 words
A method of classifying a resistor within three or more classes of resistance values defined by nulls of a multiple null direct current Wheatstone bridge comprising placing a resistor to be classified in said dual null Wheatstone bridge as an unknown resistance and observing between which nulls the resistor value lies or whether it lies above or below all nulls to classify it accordingly.
Claim 12
Independent Claim
64 words
A method of classifying a resistor within three or more classes of resistance values defined by nulls of a multiple null direct current Wheatstone bridge comprising placing a resistor to be classified in said dual null Wheatstone bridge as an unknown resistance and observing between which nulls the resistor value lies or whether it lies above or below all nulls to classify it accordingly.
References Cited (Backward Citations)
US2393669A
Cited
US2479051A
Cited
US2925554A
Cited
US3461383A
Cited
US3491293A
Cited
US3646435A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-07 | 1977-07-09 | 1978-01-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-07 | 1981-07-09 | 1982-01-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-07 | 1985-07-09 | 1986-01-08 | $7700.00 | Window Closed / Lapsed |