Patent US5737101A successfully refreshed from Google Patents.
Patent US3555366A successfully refreshed from Google Patents.
US3555366A
Expired / Lapsed
US
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Monitor circuit
Assignee: AT&T Inc
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Filing: 1968-09-18
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Granted: 1971-01-12
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Expires: 1988-09-18
Abstract
Abstract A DARLINGTON CIRCUIT MAINTAINS CURRENT THROUGH THE COIL OF A RELAY. IN RESPONSE TO SIGNALS BEING MONITORED, THE DARLINGTON CIRCUIT MAY REDUCE THE COIL CURRENT. A TRANSISTOR, WHOSE EMITTER-COLLECTOR PATH IS IN SERIES WITH THE RELAY COIL, THEN RESPONDS TO THE DROP IN VOLTAGE ACROSS THE RELAY COIL AND EXTINGUISHES THE CURRENT THEREIN.
Inventors
- 👤 William J Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:05
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/42; H04M3/487; H04M3/4872
Claims Analysis
Total Claims: 0
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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) | 1974-01-11 | 1974-07-13 | 1975-01-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-11 | 1978-07-13 | 1979-01-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-11 | 1982-07-13 | 1983-01-12 | $7700.00 | Window Closed / Lapsed |