Patent US3598924A successfully refreshed from Google Patents.
US3598924A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Line holding circuit for a multiline telephone system
Assignee: TELRAD TELECOMMUNICATION AND ELE
•
Filing: 1969-05-01
•
Granted: 1971-08-10
•
Expires: 1989-05-01
Abstract
Abstract The invention relates to a line holder circuit for a multiline telephone system which allows for the line to be held when the user, by actuating the line extension contacts, wishes to establish communication with an associated extension.
Inventors
- 👤 Daniel Zucker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 20:25
CPC Classifications
H; H04; H04M; H04M9/00; H04M9/002; H04M9/005; H04M9/006
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
133 words
In a telephone instrument for use in a multiline telephone system, a plurality of like line holding memory circuits each circuit comprising a silicon controlled rectifier connected in series between a handset cradle switch of the instrument and a terminal adapted for connection on the one hand to a holding relay and on the other hand to corresponding terminals in other instruments of the system, a gating circuit coupled to the gate of the silicon controlled rectifier and comprising a line key contact connected to a hold key of the instrument and a capacitor, one plate of which is connected via a line key contact to earth and and through a resistance to a current supply source and the other plate of which is coupled to the cathode of said silicon controlled rectifier.
Claim 2
Dependent Claim
133 words
In a telephone instrument for use in a multiline telephone system, a plurality of like line holding memory circuits each circuit comprising a silicon controlled rectifier connected in series between a handset cradle switch of the instrument and a terminal adapted for connection on the one hand to a holding relay and on the other hand to corresponding terminals in other instruments of the system, a gating circuit coupled to the gate of the silicon controlled rectifier and comprising a line key contact connected to a hold key of the instrument and a capacitor, one plate of which is connected via a line key contact to earth and and through a resistance to a current supply source and the other plate of which is coupled to the cathode of said silicon controlled rectifier.
References Cited (Backward Citations)
US3420963A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-08-09 | 1975-02-08 | 1975-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-09 | 1979-02-08 | 1979-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-09 | 1983-02-08 | 1983-08-10 | $7700.00 | Window Closed / Lapsed |