US3821486A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bridge type supervisory detector with reduced breakdown voltage requirements
Assignee: AT&T Inc
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Filing: 1973-06-22
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Granted: 1974-06-28
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Expires: 1993-06-22
Abstract
Abstract A bridge-type supervisory detector for communication lines is provided with transistor circuits connected to each cross-arm of the bridge which provide output currents dependent upon the voltages of the respective line conductors. The breakdown voltage requirements placed on the detector itself and upon the differential amplifier which follows are thereby reduced and both may be fabricated readily and inexpensively with presently existing thin film and integrated circuit techniques.
Inventors
- 👤 H Mussman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:27
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/2272
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
189 words
A supervisory detector for monitoring the operative state of a communication path which includes a pair of line conductors, a source of direct potential, and a pair of feed impedances connecting respective ones of said line conductors to opposite sides of said source, said detector comprising a pair of circuit paths cross-connected from respective ones of said line conductors to the other sides of said source thereby forming a bridge circuit with said feed impedances, each of said circuit paths including a pair of resistances one of which has an exterior end connected to said line conductor and an interior end and the other of which has an exterior end connected to said source and an interior end, a common output terminal, and circuit means both to maintain the interior ends of said resistances at substantially constant potentials and to provide at said common output terminal a current dependent upon the voltage at the line conductor end of said circuit path, and means energized in response to a difference between currents at said common output terminals for generating an output indicative of the operative state of said communication path.
Claim 2
Dependent Claim
189 words
A supervisory detector for monitoring the operative state of a communication path which includes a pair of line conductors, a source of direct potential, and a pair of feed impedances connecting respective ones of said line conductors to opposite sides of said source, said detector comprising a pair of circuit paths cross-connected from respective ones of said line conductors to the other sides of said source thereby forming a bridge circuit with said feed impedances, each of said circuit paths including a pair of resistances one of which has an exterior end connected to said line conductor and an interior end and the other of which has an exterior end connected to said source and an interior end, a common output terminal, and circuit means both to maintain the interior ends of said resistances at substantially constant potentials and to provide at said common output terminal a current dependent upon the voltage at the line conductor end of said circuit path, and means energized in response to a difference between currents at said common output terminals for generating an output indicative of the operative state of said communication path.
Claim 3
Dependent Claim
57 words
A supervisory detector in accordance with claim 1 in which, in each of said circuit paths, the current at said common output terminal is the sum of a current proportional to the voltage at the line conductor end of the circuit path and a current proportional to the voltage at the source end of the circuit path.
Claim 4
Dependent Claim
49 words
A supervisory detector in accordance with claim 1 in which said circuit means includes at least one transistor having its emitter connected to the interior end of one of said resistances, its collector connected to said common output terminal, and its base connected to a source of direct potential.
Claim 5
Dependent Claim
59 words
A supervisory detector in accordance with claim 3 in which the base of said transistor is connected to a source of direct potential biasing the emitter-base junction of said transistor in the forward direction and the collector of said transistor is connected to a source of direct potential biasing the collector-base junction of said transistor in the reverse direction.
Claim 6
Dependent Claim
47 words
A supervisory detector in accordance with claim 1 in which said circuit means includes a transistor having its emitter connected to the interior ends of both of said resistances, its collector connected to said common output terminal, and its base connected to a source of direct potential.
Claim 7
Dependent Claim
59 words
A supervisory detector in accordance with claim 5 in which the base of said transistor is connected to a source of direct potential biasing the emitter-base junction of said transistor in the forward direction and the collector of said transistor is connected to a source of direct potential biasing the collector-base junction of said transistor in the reverse direction.
Claim 8
Dependent Claim
50 words
A supervisory detector in accordance with claim 1 in which said circuit means includes a pair of transistors having their emitters connected to the interior ends of respective ones of said resistances, their collectors connected to said common output terminal, and their bases connected to a source of direct potential.
Claim 9
Dependent Claim
59 words
A supervisory detector in accordance with claim 7 in which the bases of said transistors are connected to a source of direct potential biasing the emitter-base junctions of said transistors in the forward direction and the collectors of said transistors are connected to a source of direct potential biasing the collector-base junctions of said transistors in the reverse direction.
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) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |