Patent US3218570A successfully refreshed from Google Patents.
US3218570A
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Automatic variable attenuator circuit
Assignee: Nortel Networks Ltd
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Filing: 1963-01-28
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Granted: 1965-11-16
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Expires: 1983-01-28
Abstract
No abstract record available.
Inventors
- 👤 Godier Ivan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:49
CPC Classifications
H; H03; H03G; H03G1/00; H03G1/0005; H03G1/0035; H03G1/0041
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
189 words
AN AUTOMATIC VARIABLE ATTENUATOR CIRCUIT COMPRISING INPUT CONNECTIONS FOR CONNECTING AN INPUT SIGNAL VOLTAGE THERETO, OUTPUT CONNECTIONS FOR CONNECTING AN OUTPOUT SIGNAL VOLTAGE THEREFROM; AN AMPLIFIER HAVING AN INPUT AND AN OUTPUT, THE AMPLIFIER OUTPUT BEING CONNECTED TO SAID OUTPUT CONNECTIONS; A VARIABLE ATTENUATOR NETWORK CONNECTED BETWEEN THE INPUT CONNECTIONS AND THE AMPLIFIER INPUT, AND INCLUDING A FIRST THERMISTOR AND A FIXED IMPEDANCE CONNECTED IN SERIES ACROSS SAID INPUT CONNECTIONS AND A SECOND THERMISTOR CONNECTED IN SERIES BETWEEN THE INPUT CONNECTIONS AND THE AMPLIFIER INPUT; A SECOND HEATER IN JUXTAPOSITION WITH THE FIRST THERMISTOR; A SECOND HEATER IN JUXTAPOSITION WITH THE SECOND THERMISTOR; MEANS FOR GENERATING A VARIABLE DIRECT CURRENT ERROR SIGNAL THAT IS PROPORTIONAL TO THE OUTPUT SIGNAL VOLTAGE LEVEL; A HIGH IMPEDANCE SOURCE OF DIRECT CURRENT POWER; A TRANSISTOR HAVING BASE, EMITTER AND COLLECTOR ELECTRODES, THE EMITTER AND COLLECTOR ELECTRODES BEING CONNECTED IN SERIES WITH THE SECOND HEATER ACROSS THE HIGH IMPEDANCE SOURCE, THE BASE AND EMITTER ELECTRODES BEING CONNECTED TO THE MEAANS FOR GENERATING A VARIABLE DIRECT CURRENT ERROR SIGNAL; AND A FIXED RESISTOR CONNECTED IN SERIES WITH THE FIRST HEATER ACROSS THE HIGH IMPEDANCE SOURCE.
Claim 2
Dependent Claim
189 words
AN AUTOMATIC VARIABLE ATTENUATOR CIRCUIT COMPRISING INPUT CONNECTIONS FOR CONNECTING AN INPUT SIGNAL VOLTAGE THERETO, OUTPUT CONNECTIONS FOR CONNECTING AN OUTPOUT SIGNAL VOLTAGE THEREFROM; AN AMPLIFIER HAVING AN INPUT AND AN OUTPUT, THE AMPLIFIER OUTPUT BEING CONNECTED TO SAID OUTPUT CONNECTIONS; A VARIABLE ATTENUATOR NETWORK CONNECTED BETWEEN THE INPUT CONNECTIONS AND THE AMPLIFIER INPUT, AND INCLUDING A FIRST THERMISTOR AND A FIXED IMPEDANCE CONNECTED IN SERIES ACROSS SAID INPUT CONNECTIONS AND A SECOND THERMISTOR CONNECTED IN SERIES BETWEEN THE INPUT CONNECTIONS AND THE AMPLIFIER INPUT; A SECOND HEATER IN JUXTAPOSITION WITH THE FIRST THERMISTOR; A SECOND HEATER IN JUXTAPOSITION WITH THE SECOND THERMISTOR; MEANS FOR GENERATING A VARIABLE DIRECT CURRENT ERROR SIGNAL THAT IS PROPORTIONAL TO THE OUTPUT SIGNAL VOLTAGE LEVEL; A HIGH IMPEDANCE SOURCE OF DIRECT CURRENT POWER; A TRANSISTOR HAVING BASE, EMITTER AND COLLECTOR ELECTRODES, THE EMITTER AND COLLECTOR ELECTRODES BEING CONNECTED IN SERIES WITH THE SECOND HEATER ACROSS THE HIGH IMPEDANCE SOURCE, THE BASE AND EMITTER ELECTRODES BEING CONNECTED TO THE MEAANS FOR GENERATING A VARIABLE DIRECT CURRENT ERROR SIGNAL; AND A FIXED RESISTOR CONNECTED IN SERIES WITH THE FIRST HEATER ACROSS THE HIGH IMPEDANCE SOURCE.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1968-11-15 | 1969-05-17 | 1969-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-11-15 | 1973-05-17 | 1973-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-11-15 | 1977-05-17 | 1977-11-16 | $7700.00 | Window Closed / Lapsed |