US3959602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Telephone substation circuit
Assignee: AT&T Inc
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Filing: 1974-11-19
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Granted: 1976-05-25
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Expires: 1994-11-19
Abstract
Abstract A substation circuit in accordance with the present invention includes a light emitting diode (LED) connected in parallel with the speech network of the associated telephone set, the speech network including a carbon transmitter, a receiver, and a hybrid coil. The LED is connected in series with a high ac impedance to prevent voice signals from being attenuated by the shunt path, and the LED is shunted by a varistor to provide high current and surge protection. The relative resistances of the illumination circuit and the speech network are such that at least one-fifth of the line current derived when the telephone set is connected to the longest telephone line loop is shunted through the LED path. The speech network components are selected so as to substantially compensate for the reduction in transmit level resulting from the reduced current flow through the transmitter.
Inventors
- 👤 Joel Stanley Jayson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:58
CPC Classifications
H; H04; H04M; H04M1/00; H04M1/02; H04M1/22
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
143 words
A telephone substation circuit comprising: a speech network including a carbon transmitter, a receiver, and a hybrid coil comprising a plurality of mutually coupled windings connected to the transmitter and receiver in a conjugate relationship; an auxiliary circuit connected in parallel with the speech network; and means for connecting the auxiliary circuit and the speech network to an associated telephone line, the auxiliary circuit being powered directly from the telephone line when the line connecting means is operated, the relative dc impedances of the auxiliary circuit and the speech network being such that at least one-fifth of the line current available in a longest telephone line loop is shunted through the parallel path of the auxiliary circuit, and the speech network components being such as to substantially compensate for the reduction in transmit level resulting from the reduced current flow through the transmitter.
Claim 2
Dependent Claim
143 words
A telephone substation circuit comprising: a speech network including a carbon transmitter, a receiver, and a hybrid coil comprising a plurality of mutually coupled windings connected to the transmitter and receiver in a conjugate relationship; an auxiliary circuit connected in parallel with the speech network; and means for connecting the auxiliary circuit and the speech network to an associated telephone line, the auxiliary circuit being powered directly from the telephone line when the line connecting means is operated, the relative dc impedances of the auxiliary circuit and the speech network being such that at least one-fifth of the line current available in a longest telephone line loop is shunted through the parallel path of the auxiliary circuit, and the speech network components being such as to substantially compensate for the reduction in transmit level resulting from the reduced current flow through the transmitter.
Claim 3
Dependent Claim
38 words
A telephone substation circuit as in claim 1 wherein the speech network includes a line winding, a network winding, and a transmitter path connected to the line and network windings, the transmitter path consisting of just the transmitter.
Claim 4
Dependent Claim
27 words
A telephone substation circuit as in claim 1 wherein the carbon transmitter has resistance and the carbon transmitter has a design value of at least 85 Ohms.
Claim 5
Dependent Claim
56 words
A substation circuit as in claim 1 wherein the hybrid coil includes a core having a gap therein for preventing saturation of the core at a highest line current design value and the gap is less than the gap employed to prevent saturation at said highest line current design value with the auxiliary shunt path removed.
Claim 6
Dependent Claim
152 words
A telephone substation circuit including means for illuminating the telephone comprising: a speech network including a carbon transmitter, a receiver, and a hybrid coil comprising a plurality of mutually coupled windings connecting the transmitter and receiver in a conjugate relationship; an illumination circuit including a light emitting diode connected in parallel with the speech network; and means for connecting the illumination circuit and speech network to an associated telephone line, the illumination circuit being powered directly from the telephone line when the line connecting means is operated, the relative dc impedances of the illumination circuit and the speech network being such that at least one-fifth of the line current available in a longest telephone line loop is shunted through the parallel path of the illumination circuit, and the speech network components being such as to substantially compensate for the reduction in transmit level resulting from the reduced current flow through the transmitter.
Claim 7
Dependent Claim
152 words
A telephone substation circuit including means for illuminating the telephone comprising: a speech network including a carbon transmitter, a receiver, and a hybrid coil comprising a plurality of mutually coupled windings connecting the transmitter and receiver in a conjugate relationship; an illumination circuit including a light emitting diode connected in parallel with the speech network; and means for connecting the illumination circuit and speech network to an associated telephone line, the illumination circuit being powered directly from the telephone line when the line connecting means is operated, the relative dc impedances of the illumination circuit and the speech network being such that at least one-fifth of the line current available in a longest telephone line loop is shunted through the parallel path of the illumination circuit, and the speech network components being such as to substantially compensate for the reduction in transmit level resulting from the reduced current flow through the transmitter.
Claim 8
Dependent Claim
40 words
A telephone substation circuit as in claim 5 wherein the illumination circuit further includes a high ac impedance connected in series with the light emitting diode to prevent voice signals from being attenuated by the light emitting diode shunt path.
Claim 9
Dependent Claim
52 words
A telephone substation circuit as in claim 6 wherein the illumination circuit further includes a resistor connected in series with the light emitting diode and a varistor connected in parallel with the resistor and the light emitting diode, the combination providing lightning surge and high current protection for the light emitting diode.
Claim 10
Dependent Claim
37 words
A telephone substation circuit as in claim 7 wherein the illumination circuit further includes a varistor connected between the light emitting diode shunt path and the speech network to raise the dc resistance of the speech network.
Claim 11
Dependent Claim
51 words
A telephone substation circuit as in claim 8 wherein the illumination circuit includes a pair of light emitting diodes poled oppositely to one another so that irrespective of the polarity of line current, one or the other of the light emitting diodes is illuminated when the line connecting means is operated.
Claim 12
Dependent Claim
39 words
A telephone substation circuit as in claim 5 wherein the speech network includes a line winding, a network winding, and a transmitter path connected to the line and network windings and the transmitter path consists of just the transmitter.
Claim 13
Dependent Claim
28 words
A telephone substation circuit as in claim 5 wherein the carbon transmitter has resistance and the carbon transmitter resistance has a design value of at least 85 Ohms.
Claim 14
Dependent Claim
103 words
A telephone substation circuit as in claim 5 wherein the hybrid coil comprises a line winding, a network winding, and a receiver winding and with the ratio of the turns of the network winding to the line winding designated n and the ratio of the turns of the receiver winding to the line winding designated m, the fraction of power generated by the transmitter that is delivered to the telephone line as determined by the equation ##EQU5## is greater than 0.60 and the fraction of power delivered from the line to the receiver as determined by the equation ##EQU6## is less than 0.40.
Claim 15
Dependent Claim
109 words
A telephone substation circuit as in claim 5 wherein the hybrid coil comprises a line winding, a network winding, and a receiver winding and the turns of the windings are selected to provide a line matched condition for a transmitter impedance having a design value of greater than 85 Ohms and a line impedance having a design value of 750 Ohms in accordance with the equation ##EQU7## where T is the transmitter impedance, L is the line impedance, n is the ratio of the turns of the network winding to the line winding and m is the ratio of the turns of the receiver winding to the line winding.
Claim 16
Dependent Claim
56 words
A substation circuit as in claim 5 wherein the hybrid coil includes a core having a gap therein for preventing saturation of the core at a highest line current design value and the gap is less than the gap employed to prevent saturation of said highest line current design value with the LED shunt path removed.
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) | 1979-05-25 | 1979-11-24 | 1980-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-25 | 1983-11-24 | 1984-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-25 | 1987-11-24 | 1988-05-25 | $7700.00 | Window Closed / Lapsed |