US2389666A - Telephone system - Google Patents

Telephone system Download PDF

Info

Publication number
US2389666A
US2389666A US526871A US52687144A US2389666A US 2389666 A US2389666 A US 2389666A US 526871 A US526871 A US 526871A US 52687144 A US52687144 A US 52687144A US 2389666 A US2389666 A US 2389666A
Authority
US
United States
Prior art keywords
relay
line
circuit
finder
vacuum tube
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
US526871A
Other languages
English (en)
Inventor
Roswell H Herrick
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.)
Automatic Electric Laboratories Inc
Original Assignee
Automatic Electric Laboratories Inc
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
Application filed by Automatic Electric Laboratories Inc filed Critical Automatic Electric Laboratories Inc
Priority to US526871A priority Critical patent/US2389666A/en
Application granted granted Critical
Publication of US2389666A publication Critical patent/US2389666A/en
Priority to FR930243D priority patent/FR930243A/fr
Priority to BE466457D priority patent/BE466457A/xx
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

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

Definitions

  • the present invention relates to telephone systems in general, but is concerned more particularly with automatic telephone ystems used to give service to subscribers in rural districts.
  • the principal object of the present invention is the production of new and improved circuit arrangements to provide automatic telephone service in rural areas, where the lines may have such a high resistance and be in such a relatively poor state of repair as to preclude the use of conventional automatic telephone switching equipment, without the necessity of rebuilding the outside plant.
  • One possible solution to this problem is disclosed in Patent No. 1,914,357, granted June 20, 1933, to Charles R. Brooks. This proposed solution require the use of a special repeater with each line in conjunction with conventional switching circuits.
  • the present invention eliminates the need for individual repeaters by incorporating new and improved control circuits in the switching equipment proper.
  • One of the features of the invention isth-e provision of a vacuum tube circuit common to all of the lines in the exchange that will respond to the initiation of a call from any substation and start a finder switch searching for the calling line. This feature reduces the amount of individual line equipment required to a single relay thus making the system economical.
  • the need for a separate vacuum tube circuit to detect the initiation of a call is eliminated by extending a circuit common to all of the lines through a distributor switch to a vacuum tube in the finder switch, and providing means to enable this vacuum tube to start the finder when a call is initiated in addition to its other functions.
  • a further feature of the present invention is the elimination of the magneto from the substation equipment, the supervisory and diallin operations being controlled through the use of the local battery at the substation.
  • Figs. 1 and 2 show, by means of the usual circuit drawings, a sufllcient amount of equipment in a telephone system embodying the features of the invention to enable the invention to be understood.
  • Fig. 1 shows two of the substations, A-t and B-l, connected to the exchange equipment through lines I31 and I 38, together with the common starting circuit, distributor switch, and one of a plurality of finder-connector links.
  • Fig. 2 is a modification of Fig. 1 in which the common starting circuit of Fig. 1 is eliminated.
  • the various stepping switches shown are the type in which every movement of the switch is controlled by the stepping magnet, the actual movement of'the wipers occurring during the release of the magnet.
  • the vacuum tubes shown in the drawings are the pentode type. Of course any other type may b used but the pentode is preferable since it can be designed to have a sharp cut-off characteristic thus requiring only a very small change in grid voltage to control the relay in its plate circuit.
  • the equipment shown is sufficient for a ten line exchange.
  • the number of finder-connector links required depends on the number of simultaneous conversations the exchange must handle.
  • the distributor switch is shown wired for three finder-connector links.
  • the substation rA-l is the usual local battery type modified by the addition of a calling device, a resistor, and a condenser. Provision is made for allowing a weak direct current to flow over the'line conductors to the exchange equipment, when the substation i in use, for control purposes.
  • the calling device interrupts this direct current circuit to control the stepping switches.
  • Each subscribers line terminates on the springs of a line relay at the exchange.
  • the lines are all normally connected to the input circuit of a common vacuum tube through back contacts of the line relays.
  • the removal of the receiver from the hookswitch at any of the substations will cause a current to flow over the line conductors through the back contacts of the line relay and through resistor I39.
  • the resultant voltage drop across resistor I39 reduces the grid voltage on vacuum tube I40, which is normally biased to cut-off by the voltage drop produced in resistor MI by the filament current.
  • the plate current of vacuum tube I40 then increases and operates relay I I0, which will in turn cause the finder switch previously selected by the distributor switch to start searching for the calling line.
  • the finder switch will test each line in succession by disconnecting it from the input circuit of the common vacuum tube I40 and transferring it to the input circuit of vacuum tube I42 in the finder.
  • Vacuum tube I42 is also normally biased to cut-off by the voltage drop produced across resistor I43 in its filament circuit.
  • the finder reaches the calling line the grid voltage on vacuum tube I42 will be reduced due to the voltage drop produced across resistor I44 by the current flowing over the line from the local battery at the calling substation.
  • the plate current of vacuum'tube I 42 therefore increases and operates relay I05 which causes the release of the common starting equipment and prepares the circuits to the connector which is associated with it.
  • Vacuum tube I 46 is normally biased to cut-ofi by the voltage drop produced across resistor I41 by its filament current.
  • the grid voltage of vacuum tube I46 will be reduced by the voltage drop across resistor I43 caused by the current flowing over the line from the local battery at the called substation.
  • the ,plate current of vacuum tube I46 consequently increases and operates relay I01 which prevents further application of ringing voltage to the line and establishes a transmission circuit between the calling and called lines.
  • the input circuits of vacuum tube I 42 and I46 are now connected in multiple so that as long as either party remains connected the grid voltage on vacuum tubes I42 and I46 will be reduced and will maintain the connection.
  • the substation and line equipment is identical to that previously described.
  • the lines are all normally connected to the input circuit of vacuum tube 242 through the distributor switch and the 11th bank contacts of the finder switch.
  • a circuit is established through the transmitter I28, the primary winding of the induction coil I29, the local battery I3I, and the contacts of the hookswitch I26.
  • the local battery I3I is also connected across the line I31 in series with resistor I32 and the interrupter springs I34 of the calling device I36.
  • a third circuit is established between one side of line I31, the oil-normal springs I35 of the calling device, condenser I33, the secondary winding of the induction coil I29, the receiver I21, and through make springs of the hookswitch I26 to the other side of line I31.
  • the ringer I30 is also disconnected from the line to prevent it from shunting any of the voice currents from the receiver.
  • the connection of the local battery across the line through resistor I32 allows a weak current to flow through the line conductors I31, the back contacts of the line relay, and through resistors I39 and I49 at the exchange. Resistor I49 prevents an accidental short-circuit on line I31 from making the common starting circuit inoperative.
  • the battery I3I at the substation must be poled so that this flow of current through resistor I39 will decrease the negative grid bias on vacuum tube I40.
  • the normal grid bias for this tube is obtained from the voltage drop across resistor I 4
  • Relay IIO operates, connects ground thru wiper I2I of the distributor switch DSI to wiper III of finder switch FSI, and closes a circuit through wiper I20 of DSI to rela I03 and the stepping magnet FSM--I of the finder switch FS-I Relay I03 operates, closes the circuit to the filaments of vacuum tubes I42 and I46, and prepares a multiple circuit to the stepping magnet 5 FSM-I from wiper II4 of FSI.
  • the stepping magnet of FSI operates and opens its own circuit at its interrupter springs I49, causing it to restore and advance the wipers one step. This operation is repeated as long as the circuit to the stepping magnet is completed through its interrupter springs.
  • the ground on wiper III of FSI operates the line relays IOI, I02, etc., in succession. The operation of each line relay transfers its associated line from the common starter tube I40 to vacuum tube I42 through wipers H2 and H3 of the finder switch FS--I.
  • any line which has already established connection with a finder would also have a direct voltage on it that would cause relay I in the second finder to operate.
  • the finder switch that is searching for a calling line pass over lines that have already been answered rovision is made to connect ground to wiper II4 of the finder switch after it has found a line.
  • a second finder that is searching for a calling line reaches a line that has already been answered the ground on wiper I I4 from the first finder will maintain the circuit to the stepping magnet FSM-I and relay I03 of the second finder, thus forcing the second finder switch to advance despite the operation of relay I05.
  • relay I05 When the calling line is found the operation of relay I05 opens the circuit to relay I03 and the stepping magnet of FS-I, if it has not already been opened by the release of relay H0 as previously described.
  • Relay I03 restores and closes the circuit to relay I04.
  • Relay I04 operates, closes a multiple circuit to the line relay IOI of the callin line thru wiper III of the finder switch; FS--I, closes a multiple circuit to the filaments of vacuum tubes I42 and I46, closes the circuit to relay I06 from the 11th bank contact of wiper I25 of the connector switch (IS-I, grounds wiper I I4 of the finder switch to prevent other finders from stopping on the same line, closes the circuit to the stepping magnet DSM-I of the distributor switch DS-I through its interrupter springs I50 and wiper H0 of DS--I and removes a multiple ground from bank contact II of wiper [I9 of DS-I.
  • the stepping magnet of the distributor switch DS-I now advances its wipers one step to route the next call to the following finder. If the next finder is in use the circuit to the stepping magnet of the distributor switch will be maintained.
  • Relay I IIB operates over the circuit closed by the operation of relay I04, prepares the circuit to relay I08 from wiper I22 of CSI, and prepares its own holding circuit.
  • relay I04 also connected dial tone to the calling line to inform the subscriber that the equipment was prepared for impulsing by the calling device.
  • the direct current flowing through the line and resistors I44 and I is interrupted by the calling device causing a corresponding number of interruptions to occur in the plate current of vacuum tube I42.
  • the off-normal springs I35 on the calling device I36 opens the circuit to the receiver I21 during impulsing to prevent the subscriber from hearing any objectionable clicks due to the transient currents created by the interruption of the direct current path by the interrupter springs I34 of the calling device I36.
  • Relay I05 follows the interruptions in plate current of vacuum tube I42 and restores a number of times corresponding to the digit dialled. Each time relay I05 restores it opens the circuit to relay I04, closes a holding circuit to relay I06, and closes the circuit to the stepping magnet CSM-l of the connector switch CS-I.
  • Relays'IM and I00 are slow to release and therefore remain operated during dialling.
  • the operatingcircuit to relay I06 is opened when the connector switch CS-I leaves its normal position but remains operated during dialling from the impulses it receives from a back contact of relay I05.
  • stepping magnet CSM--I operates, and each time the circuit is opened it releases and advances the wipers of 45 CS-I one step.
  • the circuit to relay I09 is closed from wiper I25.
  • Relay I09 operates, removes dial tone from the calling line and prepares the ringback tone circuit.
  • relay I08 prevents grounding wiper I22 of CS-I so as not to interfere with the connection previously established with the called line by another switch, opens the circuits to wipers I 23 and I24 of CSI to prevent the application of ringing current to the called line, and connects busy tone to the calling line to inform the calling subscriber that the called line is in use.
  • relay I08 will not be operated when relay I06 restores.
  • the restoration of relay I06 closes a circuit to the line relay I02 of the called line through wiper I22 of CS-I, causing the line relay to operate and connect the line I38 to the banks of CS-I, connects the ringing generator G-I' through springs I5I and I52 of the interrupter relay I to the called line to operate the ringer at the substation, and opens the circuit to the stepping magnet of CS-I at a second point to prevent further dialling.
  • the ringing generator is connected to the called line when relay I00 is operated.
  • the rin ing voltage is also applied to the calling line thru make springs on relay I04, break springs on relay I 08, make springs on relay I09, and through condensers I56 and I! which have a high reactance at the ringing frequency and permit only a weak current to flow in the calling line which serves to inform the calling subscriber that the called subscriber is being signalled.
  • relay I00 is also equipped with a pair of springs I53, I54, etc., for each finder-connector link.
  • Relay I01 operates, closes its locking circuit through resistor I59, opens the circuit from the interrupter relay springs I53 to resistor I48, and transfers the called line from the ringing generator G-I to the calling line, thereby establishing the talking circuit.
  • Resistor I32 and condenser I33 in the subset form a simple filter circuit that isolates the voice frequency and the direct current circuits. Since the calling and called lines are now directly connected the grid bias for vacuum tube I42 will be reduced due to the current flowing through resistor I44 from the local batteries at the calling and at the called substations as long as either party keeps his receiver oil of the hookswitch.
  • Relay I05 restores and opens the circuit to relay I 04.
  • Relay I04 restores, opens the circuit to the line relay I02 of the called line through wiper I22 of CSI, opens the circuit to the line relay ml of the calling line through wiper III of FS-I, opens the ringing generator and tone circuits to prevent interference with other lines, opens the filament circuits of vacuum tubes I42 and I46, opens the locking circuit to relay I01, removes the ground from wiper II4 of FS-I, removes the ground from the 1st bank contact of wiper II! of DSI, grounds the 11th bank contact of wiper II9 of DS-I, and closes the circuit to the stepping magnet CSMI of the connector switch CS-I through its interrupter springs I58 and wiper I25 of CSI.
  • Relay I01 restores.
  • the stepping magnet of CS--I operates self-interrupted and advances the wipers of CS-I until they reach the 11th step where the circuit to the stepping magnet CSMI and to relay I09 will be opened, allowing relay I09'to restore.
  • the line relays WI and I02 restore and the equipment is now prepared to handle another call when the distributor switch DSI again advances to the 1st step.
  • Figs. 1 and 2 are numbered with the same last two digits.
  • the leads which are common to all of the lines and correspond to those connected to resistor I30 in Fig. 1 are connected to wipers 2I1 and 2 I8 of distributor switch DS--2 in Fig. 2.
  • the bank contacts of wipers ZII and 2 I 8 of DS-2 are connected to the 11th bank contacts of wipers 2I2 and 2I3 of the corresponding finder switches.
  • the finder switches in-Fig. 2 are returned to the 11th position after each call.
  • All of the lines are thus normally extended through the back contacts of the associated line relays, wipers 2H and 2 I8 of the distributor switch, and wipers 2I2 and 2I3 of one of the finder switches to a vacuum tube 242 in one of the finders, in this case the first finder.
  • the fllament circuit to vacuum tube 242 is closed from wiper 220 of DS-2.
  • Vacuum tube 242 is normally biased to cut-ofi by means of the voltage drop in resistor 243.
  • Relay 205 operates and closes the circuit to relay 203 and the stepping magnet FSM-Z of the finder switch F S-2 through its interrupter springs 249 from ground on the 11th bank contact of wiper 2I4 of FS-2.
  • Relay ,203 operates and prepares a multiple circuit to the stepping magnet FSM-2 from wiper 2I5 of FS-Z.
  • the stepping magnet advances the wipers to the first set of bank contacts.
  • the first line relay 20I operates from wiper 2I I.
  • the first line is the calling line relay 205 will remain operated and will prevent further stepping of the finder switch as the circuit to FSM42 is opened by wiper 2l4. If the first line is already connected to another finder range there will be a ground on wiper 2 I 5 of FS-2 from the other finder that will cause this finder switch to step again even though relay 205 is operated. If the first line is idle there will be no potential across the line and the grid bias on vacuum tube 242 will increase to the cut-off value permitting relay 205 to restore. When relay 205 restores it recloses the stepping circuit to the finder switch from wiper 2I4 and causes the finder switch to continue stepping. The finder switch will continue stepping until the called line is reached at which time the net grid bias on vacuum tube 242 will be reduced by the direct current potential across the line causing relay 205 to operate.
  • Relay 205 operates and opens the circuit to relay 203 and the stepping magnet FSM2 of the finder switch FS2.
  • Relay 203 restores andcloses the circuit to relay 204 from wiper 2I4 of FS2, through make prings on relay 205. 5
  • Relay 204 operates, connects dial tone to the calling line to inform the subscriber that the equipment is prepared to receive impulses from the calling device, closes the filament circuit to vacuum tube 246, closes a multiple circuit to the filament of vacuum tube 242, grounds wiper 2I5 of the finder switch FS-2 to prevent other finders from stopping on the same line, grounds wiper 222 of the connector switch CS-2, closes the circuit to relay 296 from the 11th bank contact of Wiper 225 of CS--2, closes the circuit to the stepping magnet DSM2 of the distributor switch DS-2 through its interrupter springs 25! and wiper MS of DS 2, and removes a multiple ground from the 11th bank contact of wiper 219 of DS-2.
  • the distributor switch advances to the next idle finder as previously described for Fig. l.
  • the succeeding operations for connecting to the called line, testing to see that the line is free, signalling the called party, and establishing a transmission circuit are identical to those described for Fig. l.
  • the only difference in the two figures after this point occurs when both parties restore their re DC alternation to the hookswitch, allowing relay 2% to restore.
  • Relay 285 releases relay 284 which restores and closes the self-interrupting circuit to the stepping magnet CSM2 of the connector switch CS2 from wiper 225 of CS2 thru its interrupter springs 258, causing it to return its wipers to the 11th step.
  • Relay 284 also closes the self interrupted circuit to the stepping magnet FSM-Z of the finder switch FS-Z from Wiper 2M of FS-Z through its interrupter springs 249, causing the finder switch to restore its wipers to the 11th step.
  • a calling device at each local battery substation arranged to interrupt the said current flow in accordance with th digits in the telephone numbers of called subscribers, a space discharge device in said automatic switch, and means controlled by said space discharge device for directing said automatic switch in response to said interruptions of said current flow to set up connections to said called subscribers.
  • each finder means associating the control element of one of said vacuum tubes with said common circuit, means controlled by said vacuum .tube for starting the operation of its associated finder in response to said current fiow, means for associating the control element of said vacuum tube with said lines successivelyas the movement of the finder progresses in order to test the lines, and means controlled by said vacuum tube for terminating the operation of the finder in response to said current flow and for seizing the calling line when it is reached.
  • automatic switches in the exchange a calling device at each local battery substation arranged to interrupt the said current flow in accordance with the digits in the telephone numbers of called subscribers, and means. controlled by said second vacuum tube for directing said 11.
  • automatic telephone lines entering the exchange local battery telephone substations on each one of said lines, each provided with a local battery arranged to energize the transmitter thereat, circuit arrangements for setting up a current fiow from the local battery at a calling substation over the associated line to the automatic exchange, a pluraltiy of finders having access to said lines, a vacuum tube common to said finders, and means controlled by said vacuum tube in response to said current flow for operating one of said finders into association with said lines successively.
  • finders having access to said lines, means for operating one of said finders into association with said lines successively, a control device in said finder, means for associating said control device with said lines successively in order to test the lines as the movement of the finder progresses, and means controlled by said control device in response to said current flow for terminating the operation of the finder and for seizing the calling line when it is reached.
  • an automatic telephone exchange system telephone lines entering the exchange, 10- cal battery telephone substations on each one of said lines, each provided with a local battery arranged to energize the transmitter thereat, a common circuit, circuit arrangements for setting up a current fiow from the local battery at a calling substation over th associated line to the automatic exchange, a plurality of finders having access to said lines, a vacuum tube in each finder, means associating the control element of one of said vacuum tubes with said common circuit, and means controlled by said vacuum tube for starting the operation of its associated finder in response to said current flow.
  • a selecting system a plurality of lines, an automatic progressive movable switch, means controlled over any one of said lines for starting said switch and causing it to successively disassociate said lines from said control means and associate said lines with said switch, and means for terminating the operation of said switch when a particular line is reached and for maintaining that line in associaton with the switch.
  • a telephone exchange system telephone lines entering the exchange, a plurality of finders having access to said lines, means controlled over any one of said lines for starting one of said finders and causing it to successively disassociate said lines from said control means and associate said lines with said one finder, and means for terminating the operation of said one finder when a particular line is reached and for maintaining that line in association with said one finder.
  • an exchange In an automatic telephone system, an exchange, a plurality of telephone lines entering the exchange, a subscriber substation on each of said lines, each substation having a local battery arranged to energize the transmitter thereat, circuit arrangements for setting up a current flow from the local battery at a calling substation over the associated line to the exchange, automatic switches in the exchange accessible to any of said lines, a circuit common to said plurality of lines, and means responsive 'to said current flowing in said common circuit to effect a connection between a calling line and one of said automatic switches.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Devices For Supply Of Signal Current (AREA)
US526871A 1944-03-17 1944-03-17 Telephone system Expired - Lifetime US2389666A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US526871A US2389666A (en) 1944-03-17 1944-03-17 Telephone system
FR930243D FR930243A (fr) 1944-03-17 1946-07-04 Système téléphonique
BE466457D BE466457A (enrdf_load_stackoverflow) 1944-03-17 1946-07-05

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US526871A US2389666A (en) 1944-03-17 1944-03-17 Telephone system

Publications (1)

Publication Number Publication Date
US2389666A true US2389666A (en) 1945-11-27

Family

ID=24099157

Family Applications (1)

Application Number Title Priority Date Filing Date
US526871A Expired - Lifetime US2389666A (en) 1944-03-17 1944-03-17 Telephone system

Country Status (3)

Country Link
US (1) US2389666A (enrdf_load_stackoverflow)
BE (1) BE466457A (enrdf_load_stackoverflow)
FR (1) FR930243A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2616980A (en) * 1948-04-26 1952-11-04 Hartford Nat Bank & Trust Co Flip-flop circuit for operating a switch
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

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2616980A (en) * 1948-04-26 1952-11-04 Hartford Nat Bank & Trust Co Flip-flop circuit for operating a switch
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
BE466457A (enrdf_load_stackoverflow) 1946-08-31
FR930243A (fr) 1948-01-20

Similar Documents

Publication Publication Date Title
US2283610A (en) Telephone system
US2149646A (en) Automatic telephone system
US2115320A (en) Automatic telephone system
US2389666A (en) Telephone system
USRE23056E (en) Relay automatic telephone system
US2262595A (en) Telephone system
US1910972A (en) Telephone system
US2052051A (en) Telephone system
US2427000A (en) Coin-operated telephone system
US2294907A (en) Telephone system
US2100523A (en) Automatic telephone system
US2567115A (en) Electronic director
US2135921A (en) Automatic telephone system
US1673420A (en) Automatic telephone system
US2515783A (en) Controlling circuits for rotary connector switches
US2530104A (en) Relay automatic telephone system
US2706747A (en) Selector repeater for telephone systems
US1674677A (en) Connecter-switch circuit
US2170403A (en) Telephone system
US2458262A (en) Relay selector circuit arranged to simultaneously test a selected group of trunks
US2105898A (en) Telephone exchange system
US2225305A (en) Telephone system
US1753491A (en) Automatic telephone system
US2142658A (en) Telephone system
US1935910A (en) Telephone system