US2295032A - Communication exchange system - Google Patents

Communication exchange system Download PDF

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Publication number
US2295032A
US2295032A US286220A US28622039A US2295032A US 2295032 A US2295032 A US 2295032A US 286220 A US286220 A US 286220A US 28622039 A US28622039 A US 28622039A US 2295032 A US2295032 A US 2295032A
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US
United States
Prior art keywords
line
common
relay
lines
wire
Prior art date
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 - Lifetime
Application number
US286220A
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English (en)
Inventor
Deakin Gerald
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
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.)
Filing date
Publication date
Priority to NL57724D priority Critical patent/NL57724C/xx
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Priority to US286220A priority patent/US2295032A/en
Priority to GB10549/40A priority patent/GB541768A/en
Priority to CH235878D priority patent/CH235878A/de
Priority to FR867450D priority patent/FR867450A/fr
Application granted granted Critical
Publication of US2295032A publication Critical patent/US2295032A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04Q—SELECTING
    • H04Q3/00—Selecting arrangements

Definitions

  • H represent the hook switches of anumber of subscribers telephone sets which are respectively connected to the several lines a-ba
  • each of these lines 2t-br has connected to it a number of simple ohmic resistors J, K, L.
  • the L resistor which may be of the order of 50,000 ohms is permanently connected to the b wire of each line and its free end is connected to the negative pole of the exchange battery whose positive terminal is grounded in conventional fashion.
  • the K resistor associated with each line is preferably equal in resistance to the L resistor and is connected at its free end to the common start wire lc preferably through the individual line resistor J.
  • a common start circuit S For starting one or more free line finders to Search for a calling line a common start circuit S is provided.
  • This circuit S comprises a vacuum tube V whose anode current constantly energizes an associated relay X except when the grid of this tube V is driven negative by a potential applied to the control wire 7c.
  • the grid of tube V In the absence of any current received over control wire lc the grid of tube V is normally maintained at ground potential, or any other desired reference potential, by high resistance grid leak G which is connected to ground as shown, or to a bias source of any desired potential.
  • An auxiliary relay Y of slow release type is provided and connected as shown to be operated upon the release of relay X. In the simple system shown in Fig. 1 the control wire lc is directly connected to the start wire lc' as shown.
  • a common test circuit T In addition to the common start circuit S a common test circuit T generally similar to S is provided.
  • This circuit T comprises the vacuum tube V whose anode current normally energizes relay X', and also comprises a leak G and an auxiliary relay Y controlled from relay X.
  • the grid of tube V is connected to the test wire c of the first free line finder such as line finder I, through a common allotting device N which may be a relay chain r selecting switch and which operates in a manner well known per se to connect three wires f, c' and g of the rst idle line finder circuit to the corresponding three wires of the common test circuit as shown.
  • relay Y back contact of relay Y to the grid of tube V.
  • the resulting decrease of anode current releases relay X, thus energizing relay Y in an obvious manner.
  • a back contact of relay Y disconnects the grid of V, thus reener- I gizing relay X, but relay Y remains energized for an interval due to its slow release characteristics.
  • switch magnet M in series with its own interruptor contacts if the switch is of step by step type, or directly if it is of power driven type
  • wipers W of the line finder switch MW to hunt for the calling line.
  • relay P may be omitted from the line nder of Fig. 1 or from that of Fig. 3. In such case magnet M and its interruptor if any will be directly connected in place of the relay P.
  • relay Y energizes relay R in the line iinder which switches-through the a and b wires to the two windings of balanced bridge relay Q and simultaneously places ground on the c wire of the line finder and conductor n which extends to the common allotting device in order to cause this allotter to associate the test circuit T with the next idle line nder in known manner.
  • bridge relay Q In the line nder I, which is now connected to the calling line, bridge relay Q energizes over the line loop in the usual fashion, thus holding relay R over an obvious locking circuit of the latter. The subsequent operations of the equi ment beyond the line finder take place in the usual manner preferably under control of bridge relay Q.
  • any such line will apply ground potential to this common start wire lc' through its resistor J.
  • Such ground potential will not tend to falsely initiate a call because tube V requires a negative potential for releasing relay X.
  • resistor J is preferably made large in comparison with resistors K and L and the number of subscribers lines which are common to the start line k' is preferably maintained reasonably low.
  • each K and L resistor is desirably more than l and preferably of the order of 100 in order to reduce transmission losses to a negligible amount. If necessary a ratio as low as 3 may be used although this will result in a loss of almost one decibel.
  • the leakages of the telephone lines will often be of the order of a few megohms or tens of megohms, and thus the combined leakage of 100 such lines would, when no c wires were grounded, give a potential approaching or even exceeding the negative potential given by one calling line v in the presence of 1 0 busy lines whose c wires are grounded.
  • the resistances of the lines are unusually high to common as many as 50 or 100 lines in the simple manner shown in Fig. l, with suiiicient operating margins to give good reliability
  • the line finders are of a type serving a comparatively large group of lines such as 100 or 200 lines, I prefer to modify the arrangement of Fig. l as shown in Fig. 2.
  • the lines are not all commoned to the same start wire 7c', but are commoned in groups (of which only two groups are illustrated) which are shown as each comprising three lines but which in practice may each comprise 5 or lines.
  • a constantly operating commutatingdevice which may be an ordinary relay chain or selector switch, but which preferably is a light motor driven rotary switch or commutator adapted to run continuously for a long time without appreciable wear and designed with very light contact pressures, which are permissible in view of the high impedances and small currents associated therewith.
  • This commutating device should complete its cycle within about one or two seconds, or preferably within a fraction of a second.
  • the start wires lc will be substantially continually connected to wire lc even though not actually connected thereto for more than a fraction of the time.
  • Fig. 2 employing semi-common k' wires.
  • the lines will be grouped in say 10 subgroups of 10 lines each, the 10 lines of each subgroup being commoned by means of resistors and the subgroups being successively associated with the common control wire k in the manner clearly shown in Fig. 2-
  • Fig. 3 represents a preferred form of the common start circuit S and the common test circuit T of Fig. l.
  • one single common circuit ST replaces the two common circuits S and T of Fig. l.
  • the remainder of the system is essentially as shown in Fig. l, excepting that the line finders are slightly modied so that the battery for relay P is supplied from a back contact of relay R rather than from a common multiple associated with common start circuit S as shown in Fig. 1.
  • the modification shown in 3 may be used with the simple system of Fig. l wherein the J resistors are actually continually connected to the wire 7c or in the preferred system (obtained by modifying Fig. l according to Fig. 2) wherein the J resistors are only substantially continually connected to the control Wire 7c.
  • Fig. 3 The manner of operation of Fig. 3 is as follows: Upon the initiation of a call negative potential is received over wire k as in the case of Fig. l and this potential passes over back contacts of relays Y and Z to the grid of tube V" thus causing the release of relay X". The release of relay X energizes relay Z" over back Contact of X" and back contact of Y". The consequent operation of relay Z transfers the grid lead of tube V to the c wire of the line finder while another contact of relay Z simultaneously energizes relay P in the line nder to cause magnet M to step the wipers W around in search of the calling line.
  • relays Z and Y The locking circuit of relays Z and Y" is broken, thus releasing relay Z immediately, but relay Y remains energized for an interval because of its slow release characteristics.
  • the release of Z causes P to release thus stopping switch MW.
  • relay Y relay R is energized over back contact X, front contact Y" and wire g, and the operation of this relay R breaks the circuit of relay P (already broken by Z"), applies a ground to Wire n to cause the allotter N to connect ST to the next line nder after the release of relay Y and switches the a and b wires through to bridge relay Q so that the latter ⁇ operates in the usual manner and holds relay R.
  • Y releases and the allotter transfers ST to the next line finder.
  • the tubes V, V' and V" may be grid controlled gaseous discharge tubes of the trigger type instead of high vacuum tubes so as to remain conducting when once ignited.
  • a special battery with grounded negative may be used for feeding the L resistors and relays X, X and X may be correspondingly modified to operate upon the initiation of a call.
  • high vacuum tubes may be used with a self-locking circuit of known type to remain either conducting or non-conducting until reset. Any of these expedients will permit a very brief contacting time for the commutating device D, thus permitting a very rapid operation of this device while still insuring operation (or release) of relay X.
  • such lines may be segregated and served by conventional equipment including line and cutoff relays. Or without segregating such lines, line and cutoff relays may be added thereto and instead of connecting the leaky lines directly to the start circuits of my invention the line relays may be connected to actuate such start circuits.
  • my invention may be used in part as well as in its entirety.
  • the start circuit arrangement of the invention may be used without the special test circuit of the invention.
  • the testing may be performed across the a and b wires with a simple bridged test relay such as Q, testing only lines whose c wires are ungrounded.
  • nders may be started simultaneously or if the finders have two or three home positions two or three finders may be started.
  • the group of lines associated with one iinder may be split and two separate start circuits associated therewith.
  • the allotter may be arranged to start not simply the first idle iinder but rather the first idle finder which is occupying such a home position as to find the calling line most quickly ⁇
  • a telephone or the like exchange system comprising a number of subscribers lines each having a first and a second conductor, a subscribers station connected to each line and including means for varying the conductance between said conductors of said line to initiate a call, a, high ohmic resistance per line each resistance being substantially non-reactive and having one end permanently connected to the rst conductor of its associated line and its other end permanently connected to a common return point, a common start circuit sufficiently sensitive to be actuated in response to the said variation of the conductance between the conductors of one of said lines even in series with the associated high resistance, said common start circuit being connected to said common return point, and means for providing connection between said common start circuit and the second conductor of each line to cause the actuation of said circuit in response to the intiation of a call comprising a common control conductor connected to said start circuit, a further high ohmic resistance per line each of said further resistances having one end permanently connected to the second conductor and its associated line and constantly operating distributor -me
  • a telephone or the like exchange system comprising a number of subscribers lines each having a first and a second conductor, a subscribers station connected to each line and including means for varying the conductance between said conductors of said line to initiate a call, a high ohmic resistance per line each resistance being substantially non-reactive and having one end permanently connected to the rst conductor of its associated line and its other end permanently connected to a common return point, a common start circuit sufliciently sensitive to be actuated in response to the said variation of the conductance between the conductors of one of said lines even in series with the associated high resistance, said common start circuit being connected to said common return point, and means for providing connection between said common start circuit and the second conductor of each line to cause the actuation of said circuit in response to the initiation of a call comprising a common control conductor connected to said.
  • a telephone or the like communication exchange system comprising a number of subscribers lines extending to a central exchange and each having a rst and a second conductor symmetric to ground, a subscribers station connected to each line and including means for varying the conductance between said conductors of said line to initiate a call, a rst and a second high ohmic resistance of approximately equal value per line, each resistance having a value at least five times as high as the impedance with ⁇ respect to communication frequencies of its associated line with its connected station as seen from the exchange, and the rst resistance having one end permanently connected to the rst conductor of its associated line and its other end permanently connected to a common return point which is at ground potential at least with respect to communication frequencies, and the second resistance having one end permanently connected lto the se-cond conductor of its associated line, a third conductor individually associated with each line within the exchange and permanently connected to the other end of the associated second resistance, a common control conductor, a.
  • common start circuit suiiciently sensitive to be actuated in response to the said variation of the conductance between the conductors of one of said lines even in series with both the associated high resistances said common start circuit being connected between said common return point and said common control conductor, means for providing connection between said common control conductor and the third conductor of each line to cause the actuation of said circuit in response to the initiation of a call, and means for grounding said third conductor of any line at least with respect to communication frequencies during the communication period of a call over such line, whereby said line and connected resistances are symmetric to ground during communication.
  • a telephone or the like exchange system comprising a number of subscribers lines extending to a central exchange and each having a nrst and a second conductor, a subscribers station connected to each line and including means for closing a loop connection between said conductors of said line to initiate a call, a first and a second high ohmic resistance per line each resistance having a value at least ve times as high as the impedance with respect to communication frequencies of its associated line with its connected station as seen from the exchanges, and the first resistance having one end permanently connected to the rst conductor of its associated line and its other end permanently connected to a common return point, and the second resistance having one end permanently connected to the second conductor of its associated line, a third conductor individually associated with each line within the exchange and permanently connected to the other end of the associated second resistance, a common control conductor, a common start circuit sufficiently sensitive to be actuated in response to the closed condition of said loop connection even in series with both the associated high resistances, said common start circuit being connected between said common return point and
  • a system according to .claim 4 wherein said means for providing connection between said common control conductor and the third conductor ci each line comprises constantly operating distributor means for connecting said common control conductor to the third conductors of the several lines in rapid succession.
  • said means for providing connection between said common control conductor and the third conductor of each line comprises a third high ohmic resistance per line each such third resistance having one end permanently connected to the third conductor of its associated line and its other end permanently connected to said common control conductor.
  • said means for providing connection between said common control conductor and the third conductor of each line comprises a third high ohmic resistance per line each such third resistance having one end permanently connected to the third conductor of its associated line, a plurality of semi-common start conductors each connected to the other ends .of a plurality ofsaid third resistances, and constantly operating distributor means for connecting said common control conductor successively to said semi-common start conductors.
  • a telephone or the like exchange system comprising a number of subscribers lines extending to a central exchange and each having a rst and a second conductor, a subscribers statio-n connected toieach line and including means for closing a loop connection between said conductors of said line to initiate a call, a rst and a second high ohmic resistance per line each resistance having a value at least ve times as high as the impedance with respect to communication frequencies of its associated line With its connected station as seen from the exchanges, and the rst resistance having one end permanently connected to the rst conductor of its associated line and its other end permanently connected to a common return point, and the second resistance having one end permanently connected to the seco-nd conductor of its associated line, a third conductor individually associated with each line within the exchange and permanently connected to the other end of the associated second resistance, a common start circuit suiciently sensitive to be actuated in response to the closed condition of said loop connectlon even in series with both the associated high resistances said
  • said common start circuit comprises electron discharge means and relay means actuated thereby.
  • each of said first and second high ohmic resistances has sufcient resistance to cause substantially no impairment of the transmission of speech nor of any auxiliary signals of alternating and direct current types which are customarily transmitted over telephone Wires.
  • each of said rst and second high ohmic resistances has a value of at least 10,000 ohms.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Monitoring And Testing Of Exchanges (AREA)
  • Interface Circuits In Exchanges (AREA)
US286220A 1939-07-24 1939-07-24 Communication exchange system Expired - Lifetime US2295032A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL57724D NL57724C (en(2012)) 1939-07-24
US286220A US2295032A (en) 1939-07-24 1939-07-24 Communication exchange system
GB10549/40A GB541768A (en) 1939-07-24 1940-06-18 Communication exchange systems
CH235878D CH235878A (de) 1939-07-24 1940-06-26 Fernmeldeamtsanlage mit zum mindesten teilweisem Wählerbetrieb.
FR867450D FR867450A (fr) 1939-07-24 1940-10-10 Systèmes de communications à bureaux centraux

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US286220A US2295032A (en) 1939-07-24 1939-07-24 Communication exchange system

Publications (1)

Publication Number Publication Date
US2295032A true US2295032A (en) 1942-09-08

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Application Number Title Priority Date Filing Date
US286220A Expired - Lifetime US2295032A (en) 1939-07-24 1939-07-24 Communication exchange system

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US (1) US2295032A (en(2012))
CH (1) CH235878A (en(2012))
FR (1) FR867450A (en(2012))
GB (1) GB541768A (en(2012))
NL (1) NL57724C (en(2012))

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471415A (en) * 1940-05-22 1949-05-31 Int Standard Electric Corp Telephone calling line identification system
US2553605A (en) * 1946-06-20 1951-05-22 Int Standard Electric Corp Busy indication in electronic switching equipment for automatic telephone exchanges
US2581457A (en) * 1942-06-15 1952-01-08 Int Standard Electric Corp Electronic stop circuit for switches
US2662119A (en) * 1948-01-08 1953-12-08 Hartford Nat Bank & Trust Co Line-finder stopping circuit
US2699467A (en) * 1951-03-16 1955-01-11 Automatic Elect Lab Telephone system and a relayless line circuit and circuits in cooperation therewith for extending a call
US2761904A (en) * 1950-11-09 1956-09-04 Int Standard Electric Corp Signalling systems used for characterizing subscriber's lines in a telephone network
US2761902A (en) * 1949-06-27 1956-09-04 Int Standard Electric Corp Automatic telephone exchange

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2471415A (en) * 1940-05-22 1949-05-31 Int Standard Electric Corp Telephone calling line identification system
US2581457A (en) * 1942-06-15 1952-01-08 Int Standard Electric Corp Electronic stop circuit for switches
US2553605A (en) * 1946-06-20 1951-05-22 Int Standard Electric Corp Busy indication in electronic switching equipment for automatic telephone exchanges
US2662119A (en) * 1948-01-08 1953-12-08 Hartford Nat Bank & Trust Co Line-finder stopping circuit
US2761902A (en) * 1949-06-27 1956-09-04 Int Standard Electric Corp Automatic telephone exchange
US2761904A (en) * 1950-11-09 1956-09-04 Int Standard Electric Corp Signalling systems used for characterizing subscriber's lines in a telephone network
US2699467A (en) * 1951-03-16 1955-01-11 Automatic Elect Lab Telephone system and a relayless line circuit and circuits in cooperation therewith for extending a call

Also Published As

Publication number Publication date
CH235878A (de) 1944-12-31
NL57724C (en(2012))
FR867450A (fr) 1941-10-27
GB541768A (en) 1941-12-10

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