Patent US4644579A successfully refreshed from Google Patents.
US4644579A
Expired / Lapsed
US
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Shunt regulator for hands-free telephone
Assignee: Nortel Networks Ltd
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Filing: 1985-06-18
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Granted: 1987-02-17
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Expires: 2005-06-18
Abstract
Abstract In a loudspeaking telephone the power supply to the loudspeaker amplifier is shunted by a regulator which functions as a programmable Zener diode. Under conditions of low available line current, e.g. where two similar instruments are operated in parallel at the end of a long line, the regulator voltage is reduced in value to disable the amplifier and conserve power to maintain the basic operating functions of the telephone.
Inventors
- 👤 Edward J. W. Whittaker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 15:02
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/60; H04M1/6033; H04M19/00; H04M19/02; H04M19/04; H04M9/00; H04M9/08; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
89 words
A shunt regulator circuit for a telephone instrument connected to a telephone line for controlling a current supply to a loudspeaker amplifier in said telephone instrument, the circuit including said amplifier which is responsive to an input signal representative of the magnitude of current on the line, and a voltage regulator coupled in parallel with said current supply, such that, when the line current is less than a predetermined value, the output voltage of said regulator is progressively reduced with diminishing line current so as to disable said amplifier.
Claim 2
Dependent Claim
89 words
A shunt regulator circuit for a telephone instrument connected to a telephone line for controlling a current supply to a loudspeaker amplifier in said telephone instrument, the circuit including said amplifier which is responsive to an input signal representative of the magnitude of current on the line, and a voltage regulator coupled in parallel with said current supply, such that, when the line current is less than a predetermined value, the output voltage of said regulator is progressively reduced with diminishing line current so as to disable said amplifier.
Claim 3
Dependent Claim
18 words
A shunt regulator as claimed in claim 1, wherein said signal responsive amplifier comprises a long-tailed transistor pair.
Claim 4
Dependent Claim
17 words
A shunt regulator as claimed in claim 2, wherein said voltage regulator comprises a Darlington transistor pair.
Claim 5
Dependent Claim
19 words
A shunt regulator circuit as claimed in claim 1, wherein said circuit is configured on an integrated circuit chip.
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) | 1990-02-16 | 1990-08-18 | 1991-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-16 | 1994-08-18 | 1995-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-16 | 1998-08-18 | 1999-02-17 | $7700.00 | Window Closed / Lapsed |