US3770912A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Circuit for automatically disconnecting a test set from a telephone line
Assignee: Bell Canada Inc
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Filing: 1972-07-05
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Granted: 1973-11-06
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Expires: 1992-07-05
Abstract
Abstract The invention provides a circuit for automatically disconnecting a test set from a telephone line when the subscriber requests service. Switch means connected to the telephone line are responsive to the direct current flowing through the telephone line when the subscriber goes off-hook for automatically disconnecting the test set from the subscriber telephone line.
Inventors
- 👤 W Alford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:48
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28; H04M3/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
135 words
In a noise survey set comprising a noise measuring set and means for connecting the noise measuring set directly to a subscriber telephone line through a subscriber line circuit in a central office, an automatic disconnect circuit comprising, a first switch means having a predetermined impedance and being connected to one side of the telephone line, a second switch means having a predetermined impedance and being connected to the other side of the telephone line, the impedances of said switch means being substantially equal to each other and being large relative to the impedance of the telephone line, said switch means being responsive to the direct current flowing through the telephone line when the subscriber goes off-hook for automatically disconnecting the noise measuring set from the subscriber line circuit, thereby releasing the subscriber telephone line.
Claim 2
Dependent Claim
135 words
In a noise survey set comprising a noise measuring set and means for connecting the noise measuring set directly to a subscriber telephone line through a subscriber line circuit in a central office, an automatic disconnect circuit comprising, a first switch means having a predetermined impedance and being connected to one side of the telephone line, a second switch means having a predetermined impedance and being connected to the other side of the telephone line, the impedances of said switch means being substantially equal to each other and being large relative to the impedance of the telephone line, said switch means being responsive to the direct current flowing through the telephone line when the subscriber goes off-hook for automatically disconnecting the noise measuring set from the subscriber line circuit, thereby releasing the subscriber telephone line.
Claim 3
Dependent Claim
102 words
A circuit as defined in claim 1 wherein said switch means comprise, first and second relays, the first relay having one end connected to one side of the telephone line and its other end connected to ground, the second relay having one end connected to the other side of the telephone line and its other end connected to a source of voltage, a pair of break contacts, each one serially connected in a respective side of the telephone line at a location intermediate said relays and the central office, said break contacts being operable in response to the operation of said relays.
Claim 4
Dependent Claim
51 words
A circuit as defined in claim 2 wherein the connection of the noise survey set to the subscriber line circuit includes a control lead and wherein said disconnect circuit further comprises switch means operable in response to the operation of said relays for connecting a release signal to said control lead.
Claim 5
Dependent Claim
35 words
A circuit as defined in claim 3 further comprising, a holding bridge, and a pair of make contacts operable in response to the operation of said relays for connecting said holding bridge across said relays.
Claim 6
Dependent Claim
22 words
A circuit as defined in claim 4 wherein said holding bridge includes an indicating means which is activated when said relays operate.
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) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |