US3928735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Trunk make-busy circuit
Assignee: AT&T Inc
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Filing: 1974-12-23
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Granted: 1975-12-23
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Expires: 1994-12-23
Abstract
Abstract A trunk make-busy circuit for enabling a test position to access and test the trunk circuits of a telephone central office. The trunk make-busy circuit distinguishes between subscriber busy and trouble busy ones of the trunk circuits and enables the test position to access trouble busy trunk circuits. The trunk makebusy circuit responds to the test position by removing and restoring a trunk circuit for use on subscriber calls.
Inventors
- 👤 James Blakely Kennedy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 03:43
CPC Classifications
H; H04; H04M; H04M3/00; H04M3/22; H04M3/26; H04M3/28
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
99 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service and for use in restoring the trunk to subscriber service by a trunk test circuit arranged to selectively apply voltages between a busy lead of the trunk and a ground terminal comprising directional current conducting means for making the trunk appear busy, and means responsive to one of the applied voltages for establishing a make-busy path from the ground terminal through said directional current conducting means to the busy lead and to another one of the applied voltages for interrupting said established make-busy path.
Claim 2
Dependent Claim
99 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service and for use in restoring the trunk to subscriber service by a trunk test circuit arranged to selectively apply voltages between a busy lead of the trunk and a ground terminal comprising directional current conducting means for making the trunk appear busy, and means responsive to one of the applied voltages for establishing a make-busy path from the ground terminal through said directional current conducting means to the busy lead and to another one of the applied voltages for interrupting said established make-busy path.
Claim 3
Dependent Claim
83 words
The make-busy plug set forth in claim 1 wherein said establishing and interrupting means comprises a latch relay connected in series with zener diodes, said latch relay responsive to current flow in one direction for closing make contacts and responsive to current flow in another direction for releasing said make contacts, and wherein said directional current conducting means comprises a diode connected in series combination with said make contacts, said series combination connected in parallel with said latch relay and said zener diodes.
Claim 4
Dependent Claim
147 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service and for use in restoring the trunk to subscriber service by a trunk test circuit arranged to selectively apply positive and negative voltages between a busy lead of the trunk and a ground terminal comprising a diode for making the trunk appear busy to subscriber calls and trouble busy to the trunk test circuit, a latch relay responsive to the applied negative voltage for closing make contacts and to the applied positive voltage for releasing said make contacts, a first control path serially insertable between the busy lead and the ground terminal for enabling said latch relay and comprising zener diodes connected in series with said latch relay, and a second control path connected in parallel with said first control path and comprising the diode connected in series with said make contacts.
Claim 5
Dependent Claim
147 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service and for use in restoring the trunk to subscriber service by a trunk test circuit arranged to selectively apply positive and negative voltages between a busy lead of the trunk and a ground terminal comprising a diode for making the trunk appear busy to subscriber calls and trouble busy to the trunk test circuit, a latch relay responsive to the applied negative voltage for closing make contacts and to the applied positive voltage for releasing said make contacts, a first control path serially insertable between the busy lead and the ground terminal for enabling said latch relay and comprising zener diodes connected in series with said latch relay, and a second control path connected in parallel with said first control path and comprising the diode connected in series with said make contacts.
Claim 6
Dependent Claim
168 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service by establishing a connection from a ground terminal with a make-busy terminal of the trunk and for use in restoring the trunk to subscriber service by interrupting the connection in response to a trunk test circuit applying voltages to a lead connected with the make-busy terminal comprising a first terminal connectable with the ground terminal, a second terminal connectable with the trunk make-busy terminal, a latch relay having a coil winding responsive to one of the applied voltages for closing make contacts and responsive to another of the applied voltages for releasing said make contacts, a control path connected between said first and said second terminals for enabling said latch relay and comprising zener diodes connected in series with said latch relay coil winding, and a make-busy path connected between said first and said second terminals in parallel with said control path and comprising a diode connected in series with said make contacts.
Claim 7
Dependent Claim
168 words
A make-busy plug for use in removing a telephone central office trunk from subscriber service by establishing a connection from a ground terminal with a make-busy terminal of the trunk and for use in restoring the trunk to subscriber service by interrupting the connection in response to a trunk test circuit applying voltages to a lead connected with the make-busy terminal comprising a first terminal connectable with the ground terminal, a second terminal connectable with the trunk make-busy terminal, a latch relay having a coil winding responsive to one of the applied voltages for closing make contacts and responsive to another of the applied voltages for releasing said make contacts, a control path connected between said first and said second terminals for enabling said latch relay and comprising zener diodes connected in series with said latch relay coil winding, and a make-busy path connected between said first and said second terminals in parallel with said control path and comprising a diode connected in series with said make contacts.
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) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |