US3558830A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Overvoltage transmission line protector
Assignee: Communication Technologies Inc
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Filing: 1969-04-09
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Granted: 1971-01-26
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Expires: 1989-04-09
Abstract
Abstract A telephone line is connected to local transmitting equipment through a protective device including an amplitude limiter. The amplitude limiter is effectively shunt-connected with the local equipment for the talking or transmitting mode, that is, when circuits are established for dialing or voice frequency, tone or pulsed data transmissions to the line, but not effectively shuntconnected for the ringing mode, that is, when circuits are established for bell operation on an incoming ringing signal.
Inventors
- 👤 Warren G Bender
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:59
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/738; H04M1/74; H04M1/745; H02; H02H; H02H9/00; H02H9/04
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
81 words
A circuit for connecting a telephone line to a transmitting party station of the type that is nonconducting in the on-hook condition to a direct current voltage applied between two terminals thereof connected to said line, and conductive to a direct talking current in the off-hook condition, having the combination of: a signal amplitude limiter; circuit means operable to provide a path through said limiter between said terminals; and a detector responsive to said off-hook condition to operate said circuit means.
Claim 2
Dependent Claim
81 words
A circuit for connecting a telephone line to a transmitting party station of the type that is nonconducting in the on-hook condition to a direct current voltage applied between two terminals thereof connected to said line, and conductive to a direct talking current in the off-hook condition, having the combination of: a signal amplitude limiter; circuit means operable to provide a path through said limiter between said terminals; and a detector responsive to said off-hook condition to operate said circuit means.
Claim 3
Dependent Claim
22 words
The combination according to claim 1, in which the detector is responsive to the flow of talking current through said party station.
Claim 4
Dependent Claim
27 words
The combination according to claim 2, in which the detector includes a direct current conductive impedance and circuit means responsive to direct current flowing in said impedance.
Claim 5
Dependent Claim
17 words
The combination according to claim 1, in which the detector is nonresponsive to alternating current ringing signals.
Claim 6
Dependent Claim
30 words
The combination according to claim 1, in which the detector is frequency discriminating and nonresponsive to alternating current ringing signals in a range below that of transmission by said station.
Claim 7
Dependent Claim
30 words
The combination according to claim 1, in which the detector has disabling means having two stable conditions respectively attained by differing amplitudes of direct current voltage appearing between said terminals.
Claim 8
Dependent Claim
22 words
The combination according to claim 1, in which said detector includes a relay and said circuit means include contacts of said relay.
Claim 9
Dependent Claim
25 words
The combination according to claim 7, in which said relay has an operating coil in series connection between said party station and the telephone line.
Claim 10
Dependent Claim
29 words
The combination according to claim 8, in which the relay is slow-acting and nonresponsive to alternating current ringing signals in a range below that of transmission by said station.
Claim 11
Dependent Claim
32 words
The combination according to claim 8, having a shunt connection around said operating coil and means responsive to the on-hook condition to cause said shunt connection to conduct alternating current ringing signals.
Claim 12
Dependent Claim
53 words
The combination according to claim 8, having a shunt connection around said operating coil, and means having two stable conditions respectively attained by two differing amplitudes of direct current voltage appearing between said terminals and responsive to the hiGher of said amplitudes to cause said shunt connection to conduct alternating current ringing signals.
Claim 13
Dependent Claim
14 words
The combination according to claim 11, in which the shunt connection includes a transistor.
Claim 14
Dependent Claim
22 words
The combination according to claim 11, in which the shunt connection includes a transistor having a bias circuit connected between said terminals.
Claim 15
Dependent Claim
23 words
The combination according to claim 13, in which the bias circuit includes a Zener diode having a breakdown voltage between said two amplitudes.
Claim 16
Dependent Claim
14 words
The combination according to claim 1, in which the signal amplitude limiter includes varistors.
Claim 17
Dependent Claim
19 words
The combination according to claim 1, in which the signal amplitude limiter includes varistors in series with a capacitor.
Claim 18
Dependent Claim
22 words
The combination according to claim 1, in which the signal amplitude limiter includes plural parallel and reversely connected unidirectional amplitude clipping elements.
Claim 19
Dependent Claim
34 words
The combination according to claim 1, in which the signal amplitude limiter includes two circuits for each including a diode, the circuit means having a switching element in each of said two last-mentioned circuits.
Claim 20
Dependent Claim
13 words
The combination according to claim 18, in which the switching elements are transistors.
Claim 21
Dependent Claim
33 words
The combination according to claim 18, in which the switching elements are transistors, said transistors having bias circuits including a common impedance in series connection between said party station and the telephone line.
Claim 22
Dependent Claim
26 words
The combination according to claim 1, in which the detector operates the circuit means when direct talking current flows through the party station in either direction.
Claim 23
Dependent Claim
30 words
The combination according to claim 1, in which the detector includes two direct current conductive circuits each responsive to direct current flowing in a distinct direction through the party station.
Claim 24
Dependent Claim
53 words
The combination according to claim 22, in which each of the direct current conductive circuits has disabling means having two stable conditions respectively attained by differing amplitudes of direct current voltage appearing between said terminals, one of said stable conditions producing a shunt around its direct current conductive circuit during the on-hook condition.
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) | 1974-01-25 | 1974-07-27 | 1975-01-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-01-25 | 1978-07-27 | 1979-01-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-01-25 | 1982-07-27 | 1983-01-26 | $7700.00 | Window Closed / Lapsed |