US3835258A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ring trip circuit
Assignee: International Standard Electric Corp
•
Filing: 1973-02-01
•
Granted: 1974-09-10
•
Expires: 1993-02-01
Abstract
Abstract An electronic circuit is disclosed for detecting when a telephone handset is lifted in response to ringing tone and for providing a voltage which operates a relay to interrupt the transmission of ringing current. The circuit includes an oscillator controlled by the d.c. potential difference across a resistor in series with a wire carrying ringing current to the telephone line. The oscillator is coupled through transformer windings to the circuits to be controlled.
Inventors
- 👤 Cardonnel G Le
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:14
CPC Classifications
H; H04; H04M; H04M19/00; H04M19/02; H04M19/026
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
119 words
A ringing trip circuit for connection in series with a subscriber''s line comprising a resistor for connection in series with a subscriber''s line, a low-pass filter having input terminals connected across the resistor to supply d.c. voltage from said resistor to filter output terminals, a detecting device connected to receive the d.c. voltage appearing on the output terminals of the filter and responsive thereto to provide an a.c. voltage across detecting device output terminals, means coupled to receive the a.c. voltage from the detecting device, said means including a switching devicE, and said means responding to receipt of said a.c. voltage to operate the switching device to enable disconnection of a subscriber''s line from a source of ringing current.
Claim 2
Dependent Claim
119 words
A ringing trip circuit for connection in series with a subscriber''s line comprising a resistor for connection in series with a subscriber''s line, a low-pass filter having input terminals connected across the resistor to supply d.c. voltage from said resistor to filter output terminals, a detecting device connected to receive the d.c. voltage appearing on the output terminals of the filter and responsive thereto to provide an a.c. voltage across detecting device output terminals, means coupled to receive the a.c. voltage from the detecting device, said means including a switching devicE, and said means responding to receipt of said a.c. voltage to operate the switching device to enable disconnection of a subscriber''s line from a source of ringing current.
Claim 3
Dependent Claim
29 words
A circuit as claimed in claim 1, in which the detecting device includes an oscillator, and the oscillator is responsive to the d.c. voltage to provide said a.c. voltage.
Claim 4
Dependent Claim
40 words
A circuit as claimed in claim 1, in which the detecting device includes an oscillator to provide the a.c. voltage in response to the d.c. voltage, and the oscillator includes a transistor coupled to the primary windings of a transformer.
Claim 5
Dependent Claim
80 words
A circuit as claimed in claim 1, in which the detecting device includes an oscillator responsive to the presence of the d.c. voltage to produce the a.c. voltage, the oscillator includes a transistor coupled to the primary windings of a transformer to produce the a.c. voltage across said windings, said means coupled to receive the a.c. voltage from detecting means includes rectifier means, and the secondary windings of the transformer are coupled through the rectifier means to the switching device.
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) | 1977-09-09 | 1978-03-11 | 1978-09-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-09 | 1982-03-11 | 1982-09-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-09 | 1986-03-11 | 1986-09-10 | $7700.00 | Window Closed / Lapsed |