Patent US3916111A successfully refreshed from Google Patents.
US3916111A
Expired / Lapsed
US
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Telephone ringer isolator-ringing extender
Assignee: AT&T Inc
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Filing: 1974-05-17
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Granted: 1975-10-28
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Expires: 1994-05-17
Abstract
Abstract The invention is a ringer isolator-ringing extender circuit for a multiparty telephone line. The circuit includes a pair of terminals arranged for receiving alternating current signals superimposed on a predetermined potential and a third terminal arranged for connecting with ground. A pair of parallel connected and oppositely poled silicon controlled rectifiers, one of which is arranged for slaved triggering, is interposed between one of the receiving terminals and the third terminal. A threshold circuit connected between the receiving terminals and further connected to a gate electrode of one of the rectifiers prevents conduction through the rectifiers until a signal having predetermined polarity, magnitude and duration is applied between the receiving terminals. The rectifiers are arranged for triggering at a low anode to cathode potential after initial conduction.
Inventors
- 👤 Henry Walter Ott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:36
CPC Classifications
H; H04; H04Q; H04Q5/00; H04Q5/02; H04Q5/06
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
136 words
A telephone ringer isolator-ringing extender circuit comprising: a pair of terminals for receiving an alternating current signal superimposed on a predetermined potential; a third terminal for connecting with a reference potential; a pair of parallel connected silicon controlled rectifiers interposed between one of the receiving terminals and the third terminal, the rectifiers being oppositely poled; a threshold circuit connected between the receiving terminals and further connected to a gate electrode of one of the silicon controlled rectifiers, the threshold circuit arranged for preventing conduction through both rectifiers until a signal having predetermined polarity, magnitude and duration is applied between the receiving terminals triggering initial conduction through the one silicon controlled rectifier, and the pair of silicon controlled rectifiers being arranged for triggering at a low anode-to-cathode potential after initial conduction through the one silicon controlled rectifier.
Claim 2
Dependent Claim
136 words
A telephone ringer isolator-ringing extender circuit comprising: a pair of terminals for receiving an alternating current signal superimposed on a predetermined potential; a third terminal for connecting with a reference potential; a pair of parallel connected silicon controlled rectifiers interposed between one of the receiving terminals and the third terminal, the rectifiers being oppositely poled; a threshold circuit connected between the receiving terminals and further connected to a gate electrode of one of the silicon controlled rectifiers, the threshold circuit arranged for preventing conduction through both rectifiers until a signal having predetermined polarity, magnitude and duration is applied between the receiving terminals triggering initial conduction through the one silicon controlled rectifier, and the pair of silicon controlled rectifiers being arranged for triggering at a low anode-to-cathode potential after initial conduction through the one silicon controlled rectifier.
Claim 3
Dependent Claim
34 words
A telephone ringer isolAtor-ringing extender circuit in accordance with claim 1 wherein the silicon controlled rectifiers are arranged for triggering at zero volt anode-to-cathode potential after initial conduction through the one silicon controlled rectifier.
Claim 4
Dependent Claim
50 words
A circuit in accordance with claim 1 wherein a zener diode and a conventional diode are interposed in a gate circuit of the one silicon controlled rectifier for breaking down the zener diode into reverse conduction only in response to a ring signal having the predetermined polarity, magnitude and duration.
Claim 5
Dependent Claim
48 words
A circuit in accordance with claim 3 wherein a ringer circuit capacitor of a first telephone is connected in series circuit with the pair of silicon controlled rectifiers between one of the receiving terminals and the third terminal for blocking direct current from being conducted through the ringer.
Claim 6
Dependent Claim
47 words
A circuit in accordance with claim 4 wherein a ringer circuit capacitor of a second telephone is connected in series circuit with the pair of silicon controlled rectifiers between the one receiving terminal and the third terminal for blocking direct current from being conducted through the ringer.
Claim 7
Dependent Claim
123 words
A multiparty telephone line comprising a plurality of stations, each station having a ringer circuit and a ringer isolator circuit, the ringer circuit of each station having a capacitor and the entire ringer coil arranged electrically in series for blocking direct current from being conducted through the ringer coil, and the ringer isolator circuit of each station including a pair of oppositely poled silicon controlled rectifiers, each rectifier having an anode-cathode path connected electrically in series with the ringer circuit of the same station between one side of the line and ground and one of the rectifiers having a gate connected to another side of the line for enabling conduction through the ringer circuit in a full selective signaling arrangement for four parties.
Claim 8
Dependent Claim
123 words
A multiparty telephone line comprising a plurality of stations, each station having a ringer circuit and a ringer isolator circuit, the ringer circuit of each station having a capacitor and the entire ringer coil arranged electrically in series for blocking direct current from being conducted through the ringer coil, and the ringer isolator circuit of each station including a pair of oppositely poled silicon controlled rectifiers, each rectifier having an anode-cathode path connected electrically in series with the ringer circuit of the same station between one side of the line and ground and one of the rectifiers having a gate connected to another side of the line for enabling conduction through the ringer circuit in a full selective signaling arrangement for four parties.
Claim 9
Dependent Claim
94 words
A multiparty telephone line in accordance with claim 6 wherein the ringer isolator circuit of each station comprises a trigger circuit arranged for preventing conduction through the ringer circuit of its associated station until a signal having a predetermined polarity and magnitude is applied to the two sides of the line causing initial conduction through only one of the ringer circuits, and the ringer isolator circuit associated with the initially conducting ringer circuit being arranged for triggering at zero volt between the two sides of the line after initial conduction through its ringer circuit.
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) | 1978-10-27 | 1979-04-28 | 1979-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-27 | 1983-04-28 | 1983-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-27 | 1987-04-28 | 1987-10-28 | $7700.00 | Window Closed / Lapsed |