GB1389017A – Apparatus for conversion of telephones connection in parallel to a common line to provide a private switching system
– Google Patents
GB1389017A – Apparatus for conversion of telephones connection in parallel to a common line to provide a private switching system
– Google Patents
Apparatus for conversion of telephones connection in parallel to a common line to provide a private switching system
Info
Publication number
GB1389017A
GB1389017A
GB4412971A
GB4412971A
GB1389017A
GB 1389017 A
GB1389017 A
GB 1389017A
GB 4412971 A
GB4412971 A
GB 4412971A
GB 4412971 A
GB4412971 A
GB 4412971A
GB 1389017 A
GB1389017 A
GB 1389017A
Authority
GB
United Kingdom
Prior art keywords
line
relay
exchange
supply
circuit
Prior art date
1971-03-02
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB4412971A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MECHANIC ESFAHINI B
Original Assignee
MECHANIC ESFAHINI B
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1971-03-02
Filing date
1972-03-01
Publication date
1975-04-03
1972-03-01
Application filed by MECHANIC ESFAHINI B
filed
Critical
MECHANIC ESFAHINI B
1975-04-03
Publication of GB1389017A
publication
Critical
patent/GB1389017A/en
Status
Expired
legal-status
Critical
Current
Links
Espacenet
Global Dossier
Discuss
Classifications
H—ELECTRICITY
H04—ELECTRIC COMMUNICATION TECHNIQUE
H04M—TELEPHONIC COMMUNICATION
H04M1/00—Substation equipment, e.g. for use by subscribers
H04M1/68—Circuit arrangements for preventing eavesdropping
H04M1/70—Lock-out or secrecy arrangements in party-line systems
Abstract
1389017 Automatic exchange systems BAHBAM MECHANIC-ESFAHANI 1 March 1972 [2 March 1971] 44129/71 Heading H4K A circuit which enables a plurality of subsets to share a single exchange line, is adapted to receive dial signals over the exchange line and in response thereto to connect that exchange line exclusively to one subset and to supply locally generated ringing tone to that subset and is arranged also to return to conventional shared line working in response to failure of a local power supply. As described, the circuit is said to replace the party line circuit of a conventional party line arrangement. The circuit derives power from a local mains supply and if the supply fails a relay releases to connect the subsets in parallel and to the line to give continuity of service. A detector also monitors for exchange test potential on the party line and blocks a transistor supplying power to the relay causing the circuit to switch to the conventional mode for a short test period if the test potential is detected. When the circuit operates in the exclusive mode it functions like a concentrator concentrating calls to and from the subsets on to a single exchange line with the exception that the exchange is assumed to treat the party line as an ordinary subscriber line and that for incoming calls ringing on the party line is detected and the line looped through a resistor to provide an answer signal. The calling subscriber can then dial an extra digit 1, 2 or 3 transmitting 1, 2 or 3 pulses through the resistor. These are regenerated to enable one of three relays each of which is enabled in response to a pulse, disables any previously enabled relay, disconnects itself from the regenerator and connects an adjacent relay to the regenerator. A timer times out after a sufficient time for the dialling of the extra digit and the substation associated with the then enabled relay is selected. If no relay is selected the fourth or master substation is selected. Ringing tone is derived from the mains supply and its duration timed by a transistor timer. For an outgoing call the relays are enabled cyclically and when the relay associated with an originating subset is enabled a transistor detector responds cutting off the supply to the relays. If another subset goes off-hook while the line is engaged in an established call this cutting off arrangement prevents his relay responding and connects that subset to the tone supply.
GB4412971A
1971-03-02
1972-03-01
Apparatus for conversion of telephones connection in parallel to a common line to provide a private switching system
Expired
GB1389017A
(en)
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
US12022471A
1971-03-02
1971-03-02
Publications (1)
Publication Number
Publication Date
GB1389017A
true
GB1389017A
(en)
1975-04-03
Family
ID=22388983
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB4412971A
Expired
GB1389017A
(en)
1971-03-02
1972-03-01
Apparatus for conversion of telephones connection in parallel to a common line to provide a private switching system
Country Status (2)
Country
Link
US
(1)
US3725595A
(en)
GB
(1)
GB1389017A
(en)
Families Citing this family (4)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US4000375A
(en)
*
1975-02-20
1976-12-28
Hachishiro Kawamura
Automatic call transfer circuit for a plurality of telephones
CA1200036A
(en)
*
1978-03-13
1986-01-28
Guido Panizzon
Partyline subscriber interface circuit
JPH08174358A
(en)
*
1994-12-26
1996-07-09
Fanuc Ltd
Submotor unit mounting device for machine tool
KR100901772B1
(en)
*
2007-10-08
2009-06-11
한국전자통신연구원
Device for preventing eavesdropping through speakers
Family Cites Families (5)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
US1850192A
(en)
*
1930-05-23
1932-03-22
Associated Electric Lab Inc
Lockout party-line telephone system
US3033932A
(en)
*
1957-02-08
1962-05-08
Automatic Elect Lab
Selective ringing multi-party telephone system
US3100244A
(en)
*
1959-11-26
1963-08-06
Ass Elect Ind
Inter-communication systems
US3499121A
(en)
*
1966-03-03
1970-03-03
Proctor & Associates Co
Communication system exclusion circuit
US3514544A
(en)
*
1967-04-21
1970-05-26
Charles W Chambers Jr
Party line privacy device
1971
1971-03-02
US
US00120224A
patent/US3725595A/en
not_active
Expired – Lifetime
1972
1972-03-01
GB
GB4412971A
patent/GB1389017A/en
not_active
Expired
Also Published As
Publication number
Publication date
US3725595A
(en)
1973-04-03
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Legal Events
Date
Code
Title
Description
1975-08-13
PS
Patent sealed [section 19, patents act 1949]
1976-09-29
PLNP
Patent lapsed through nonpayment of renewal fees
