US2083552A - Station selecting system - Google Patents

Description

June 15,-1937- A. s. BENJAMIN 2,083,552

STATION SELECT ING SYSTEM Filed Nov. 9, 1927 mam attozucq Patented June 15, 1937 UNITED STATES PATENT OFFICE STATION SELECTING SYSTEM Application November 9, 1927, Serial No. 232,073

43 Claims.

The present invention relates to inter-communicating station selecting systems.

More particularly the system relates to intercommunicating systems especially adapted for systems in which telegraph recorders or similar instruments are located at different points and where it may be desired to communicate at will with any one or more of the remaining instruments over a single circuit or conductor, leaving all the idle printers non-operative and providing means for indicating over the same circuit at all of the stations, when any one or more of the stations are signalling.

A primary object of the invention is to provide a switching system for telegraph or signalling systems, in which remote recorders or printers may be selectively started into operation over a common signalling circuit, either singly or in groups and providing an indication at all transmitting stations that the common circuit is in use for communication.

Other objects of the invention are such as may be obtained by the utilization of the various combinations and subcombinations set forth in the disclosure of the preferred embodiment of the invention as defined by the terms of the appended claims.

Referring to the drawing:

Figure 1 is a circuit diagram including the essential connections and apparatus for a system comprising three stations.

Figures 2 and 3 are modifications of the circuit.

Before describing the operations in detail, a brief description of the relations of the various mechanism employed will be given.

At each of the stations, A, B, and C, there is located a telegraph recorder, for example, a typewriting unit, preferably comprising a transmitter i and a printer 2, the detailed construction of 49 these mechanisms being for example such as disclosed in U. S. Patent #1567392, issued December 9, 1925, although it will be understood that any form of transmitter and receiver can be employed.

A single metallic circuit comprising a conductor 3, is provided connecting all of the stations in series although it is obvious that a single conductor and ground return could be employed.

The apparatus at each station comprises in part,

50 in addition to the printing unit referred to above, a dial code transmitter 4 of any well known type, such for example as are used in the telephone art, connected in the signalling line 3 for transmitting station selecting code combinations of impulses thereover. Line relays 5. comprise two windings one of which is biased to maintain the armature in a. normal position and the other winding of which operates in response to the code signals transmitted by the dial 4 to operate Gill selector relays 6 and 1. It will be apparent to those skilled in the art that line relays 5 may be a neutral or other equivalent form of relay. The Gill selectors used may be of any of the well known constructions, such for example as that shown in the patent to Gill #906,523, December 15, 1908, which operates in response to the predetermined code to close its contacts. Although a Gill selector is here disclosed, it is evident that anyone of the well known forms of selectors may be used. The Gill selector relays 6 at each station operate in response to individual predetermined code combinations of impulses different from the telegraph or printer operating code combinations to close the contacts of their armatures 8. The selector relays l at all the stations in turn operate in response to a common code combination of impulses different from the telegraph code combinations to close the contacts of their armatures 9 at their upper posi-- tions and to a different common code combination of impulses for closing the contacts of their armatures 9 at their lower position. It is evident, however, that variable combinations of the selectors 'I may be arranged to respond to the same code. Although here shown as connected in series with each other, it is obvious that the Gill selector relays may be connected in parallel with each other and in series with armatures 5' ofrelays 5. l. v

Each Gill selector relay 6 controls an energizing circuit for relay Ill at the contact of its armature 8, and each selector 1 controls energizing circuits for the relays II and I2 at the upper and lower contacts respectively of its armature 9.

The relays l0 and H in turn control the energizing circuit for relay l3 at their respective armatures l4 and I5 and control the shunting of resistance l6 at their respective armatures l1 and I8. Relay I2 controls the locking circuits for relays l0 and II at armature l9 and its back contact in a manner to be described in detail hereinafter and controls a second circuit for relay I3 at armature l9 and its front contact.

Relays I3 open and close the circuit for motors 20 at their armature 2|. Motors 20, when rotating, supply the motive power for the printers (not shown). Each printer while in rotation is selectively controlled by the magnet 2 responsive to code combinations of impulses.

Milliammeters 22 are connected in series with the signalling line to measure the current flow therein and to indicate when the line is busy in a manner to be described hereinafter.

The operation of the apparatus thus far de scribed is as follows:

Normally the line circuit is closed at each station through the contacts of transmitter I, the winding of line relay 5, milliammeter 22, contact 4 of the dial code transmitter, and resistance 16, all of the stations being in series in the line. Resistance i6, at each station is shunted by armatures I1 and 18 so that in effect, the resistance is disconnected from the system when no signals are being transmitted. With resistances at each station thus shunted and the apparatus normally at rest, the current flow in the signalling line is such as to cause the milliammeter to indicate normal line current, for example '75 milliamperes. This indicates to the operator at each station that the line is idle and any operator may proceed to select the desired station for communication therewith. With the apparatus at rest, an energizing circuit is completed at each station for relay l3 from negative battery, winding of relay l3, back contact and armature I, back contact and armature l5, and back contact and armature l9 to positive battery. Each relay l3, While energized, holds the energizing circuit for motor 20 open at armature 2| and the printer controlled thereby is therefore idle or at rest.

In order to illustrate the invention, it will be assumed that the operator at a remote station desires to communicate with the station A. To transmit signals it is first necessary to start the receiving printer at this station into operation preparatory to receiving the code.- This the operator accomplishes by rotating the dial of transmitter 4 at his station so as to transmit the predetermined code combinations of signals allotted to station A over the line 3. These code impulses transmitted over the signalling line operate the relay 5 at station A which in turn controls the energizing circuit for the Gill selector relays 6 and I and printer magnet 2. The circuit for the Gill selector relays 6 and 1 is completed from the positive side of battery, the back contact of armature 5' and through the winding of the Gill selector relays 6 and 1 in'series to the negative battery.

The Gill selector relay 6 responds to this code combination of impulses in the well known manner, to close the front contact of its armature 8 and a circuit is thereupon completed from the positive side of battery through the armature 8 and its front contact, and through the winding of relay ID to the negative side of battery. Upon energization of the relay in, a locking circuit is provided therefor from negative battery through the winding .of the relay ID to the front contact and armature ll, the back contact and armature l5 and the back contact and armature l9 to the positive battery.

As above set forth resistance I6 is normally shunted by the armatures i1 and I8 in engagement with their back contacts. With the resistance shunted, the current fiow through the milliammeter 22, is, as was pointed out above, the normal line current or milliamperes. When relay l0 energizes, armature l1 opens its back contact thereby opening the shunt around resistance I6 and the line current now flowing through the added resistance i6 is reduced to a lower value, for example 60 milliamperes. The new reading of the milliammeter 22 provides a visual indication at all the stations that the line is busy.

A further result of the energization of relay in is to open the energizing circuit for relay i3 at armature l4. As a result of the de-energization of the relay I3, the circuit for motor 20 is closed at armature 2| and its back contact. The motor 20 starts the receiving printer into operation in preparation for the receipt of the code combination of impulses from the transmitting station. By including in the signal circuit 3 the resistance l6 of the selected station, the current in the meter 22 has dropped from '75 to 60. The calling station now dials his own call, thereby starting his own motor and including his own resistance IS in the circuit 3, reducing the operating current from 60 to 50. The index of the meter 22 thus discloses the number of resistances 16 included in the circuit 3.

The transmitter l at the remote station is now operated to transmit signalling or message code combinations of impulses to which the relay 5 is responsive. It will be noted that the single magnet printer relay 2 at station A is connected in multiple with relays 6 and 1 and operates in response to the movement of the armature 5'. As the line impulses now being received operate the armature 5', the single magnet printer 2 responds to make a selection in the well known manner disclosed in the patent referred to above. Although the selector magnets 2 of the single magnet printers operate in response to the impulses when the station selection is made, no record is made during the station selecting period since the motors l8 are not in operation at that time and the printers are herefore idle. Energizetion and tie-energization of the relays 2 accordingly has no effect on the printers at stations where the motors remain idle. Similarly, although Gill selector relays 6 and I respond to the telegraph code signals, this has no effect on the selectors since these selectors are arranged to operate only in response to a predetermined code which is different than the code to which the printers respond.

As soon as the two stations are through communicating with each other, the operator at the remote station will transmit a disconnect code to operate the Gill selector 1 at the selected station A so as to operate its armature 9 to close its lower contact. When the armature 9 closes its lower contact, a circuit is completed from the positive side of battery over armature 9 and its lower contact, through the winding of relay l2 to the negative side of battery energizing relay l2. The energization of the relay l2 operates armature I9 to open the locking circuit for the relay l0 previously traced and closes its front contact. As a result of the armature I9 closing its front contact, a circuit is completed for relay l3 from the positive side of battery, armature l9 and its front contact and through the winding of relay l3 to the negative side of battery. Relay I3, upon energization opens the circuit for the motor 20 at armature 2|. The de-energization of the relay I0 prepares a circuit for the relay. [3 at armature H and its back contact which is completed as soon as the relay I2 is again de-energized. A short interval after transmission of the disconnect code, relay 1 is de-energized and its armature 8 disengages its back contact. Relay i2 is thereupon de-energized and the armature l9 drops to its back contact. The original circuit for the relay i3 is now again completed from the positive side of battery over armature l9 and its back contact, armature I and its ba'ckcontact, armature l4 and its back contact, and to the winding of relay It to negative battery. The relay I3 upon energization, maintains the circuit for the motor open and the receiving printer is therefore idle.

If it is desired to connect all of the stations for receiving a code combination of impulses simultaneously on the signalling line,- the code of impulses transmitted over the line are such as to operate the Gill selector relays 'I at each station for closing the upper contacts of their armature. As a result ofthe armatures 9 closing their upper contacts, circuits are completed from the positive side of the batteries at each station over armatures 9 and their front contacts, and through the windings of relays II to negative batteries. The relays II upon energization complete locking circuits for themselves from negative batteries through the windings o! relays II, the front contacts and armatures I5 and the back contacts,

and armatures I9 to positive batteries. A further result of the energization of relay at station A is to operate the armatures it which, upon energization open the shunt circuit of the resistance element I6 at station A, the eifect of which is to decrease the current flowin the signalling line to 60 milliamperes. It will be noted that the shunt for only one of the resistances I6 is opened when all of the stations are selected although the relays It at each station are energized. This prevents too great a change in the current flowing in the signalling line. Anindication is thus pro vided that the line is busy.

printers are thereupon started into operation.

In this manner all of the stations are connected in the signalling line for receiving the telegraph code. When it is desired to restore all the stations to normal the proper code combination will be transmitted for operating the Gill selectors controlled by the relays I to close armatures l] and their lower contacts, and circuits will thereupon be completed for the relays.

As soon as the armatures IQ of relays I2 move from their back contacts, the relays M are deenergized and their armatures l5 move to their back contact to again close the circuits for the relays I3. Relays I2, however, do not have looking circuits and therefore are only momentarily closed. When the relays are die-energized, their armatures move into engagement with their back contacts and the original circuits for relays It! are again completed from the positive side of batteries, armatures l9, and their back contacts, armatures I5 and their back contacts, armatures I8 and their back contacts and through the windings oi relays l 3 to the negative side of battery.

Although in the preferred embodiment of the invention, the resistance I6 is shown as normally shunted when no signalling is taking place, it is evident that the reversearrangement as shown in Figure 2 can be employed. In this modification oi the system, the resistance It is normally connected in series in the system. When relay lIl or II energizes the resistance I6 is shunted. In this case the normal flow of current is, for example 60 milliamperes, with the resistance IS in the circuit. Upon energization of either relays I0 or- I l, the resistance It is shunted and the current flowis increased to, for example, '15 milli- 1 amperes. The new milliammeter readings will indicate by its larger value that the line is busy".

A further modification is shown in Figure 3 in which the resistance I6 is connected to the back contact of armature 23 of relay I3. When the relay I3 is de-energized, the resistance I6 is shunted. Upon energization of relay I3 in the manner described above, the shunt is removed from resistance I6 to decrease the line current flow which indicates busy". By this arrangement, an indication is provided that the receiving apparatus is in operating condition and ready to receive the code combinations of impulses. At all of the remaining stations, the back contact of armature I8 is connected to one side of the resistance I6 and the armature to the other side of the resistance so that when the relay II is energized for starting the apparatus at all the stations into operation, only one shunt oi the resistance I6 is removed.

Although in the preferred form, a milliammeter to give the busy signal is disclosed, it is evident that other means of indication may be employed. Thus, for example, the milliammeter may be replaced by a marginal relay arranged to be responsive to currents exceeding sixty milliamperes, controlling a circuit to be completed when the relay is energized for illuminating a lamp or operating an indicator.

It is also evident that the milliammeter indicator could be arranged to play over a series of contacts, one of which is engaged by the mil-= liammeter indicator when the current exceeds sixty milliamperes and closes a circuit for operating an indicator either directly or through the medium of a relay.

It will be evident from the description of the in= vention that employing only a single circuit, connecting a number of stations, any one or all of the stations can be selected and started into operation from any other station. Signalling can then be carried on over the same circuit between the two stations while at the same time a visual indication is provided at all the stations showing that the circuit is busy.

Although the relay I3 is shown normally energized, it is evident that this relay may be maintained normally deenergized by completing its circuit over the front contacts of relays instead of the back contacts. A corresponding change in the circuit for motor 20 would then be necessary.

Having described the preferred embodiment of the invention, what is desired to be secured by Letters Patent and is claimed as new is:

1. An inter-communicating system for telegraph printers, comprising a plurality of stations, receivers at each of said stations, a single circuit connecting all of said stations, means including said single circuit for selecting any one and thereafter any other one of said stations, and means including said single circuit for transmitting signalling lmpulses for operating said receivers at the selected stations.

2. In an inter-communicating system, a plurality of stations, receiving apparatus at each of i said stations, a single circuit connecting all of said stations, means including said circuit for transmitting direct current signal conditions, means responsive to said direct current signal conditions for selecting one of said stations from another one of said stations to automatically start the receiver thereat into operation, means including said circuit for indicating that said receiver has been started into operation, and

means including said circuit for operating said selected station receiver from said other of said stations.

3. In a communicating system, a plurality of stations, a signalling line connecting all of said stations, means including said signalling line for transmitting code combinations of signalling conditions, means responsive to said code combinations for selecting said stations, a normally non-operating, printer-motor at each of said stations, and means individual to each of said printer-motors for automatically starting it into operation in response to the selection of its associated station.

4. In a communicating system, a plurality of stations, a single signalling circuit connecting all of said stations, means including said signalling circuit for transmitting direct current signalling conditions between any of said stations, and means operable over said signalling circuit and responsive to said direct current signalling conditions for indicating when said signalling circuit is busy and for indicating the number of stations operatively connected upon said busy line.

5. In an intercommunicating system, a plurality of stations, a single signalling circuit connecting all of said stations, means including said signalling circuit for transmitting direct current impulse conditions, means responsive to said impulse conditions for selecting one of said stations, and means operable over said signalling circuit for indicating continuously throughout the ensuing communicative period the number of responses to said means of selecting.

6. In a telegraph system. a calling station, other stations, a series line through all said stations, control means at said calling station for including in communication or excluding said other stations in said line selectively, and a signal device at said calling station indicating how many of said other stations are in communication in the said line.

7. In a telegraph system, a plurality of stations, a receiver normally non-operative at each station, a station selector at each station, said selectors each responsive to a code of signals and all selectively responsive to variant code signals, a receiver-conditioning device at each station and controlled by said station selector at that station to condition said receiver at that station to operate, a sender adapted to send code signals to which said station selectors are selectively responsive, and locking means for said receiverconditioning device, said sender being eilective to send further code signals to select other stations and to conditio n other receivers independently of the operative condition of said looking means at a first-selected station, whereby communication may be established with a plurality of independently selected stations.

8. In a telegraph system, a plurality of stations; a normally non-operative receiver at each station, a first selector at each station, said first selectors each responsive to predetermined code signals individual thereto and all selectively responsive to variant code signals, a second selector at each station, said second selectors all responsive to one predetermined code signal; means at each station to condition a receiver to operate and controlled by either said first or said second selector; and a sender adapted to send code signals to which said selectors are responsive.

9. In a telegraph system, a busy signal device adapted to be operated variably; means to onto variations in an electrical constant of said line wire, means at each station to modify the electrical constant of said line wire to control said signal, and means for telegraphic communication over said line wire.

11. In a telegraph system, a single line wire, a plurality of stations, means including said single line wire for selecting said stations one by one in any desired order up to any desired number and for connecting the selected stations for communication over said single line wire, a signal at the selecting station adapted to indicate the response of each selected station, means for starting and stopping printer-motors at said stations by remote control over said single line wire, and telegraphic apparatus at said stations all combining to form an integral equipment for point-to-point and broadcast telegraphic messages.

12. In a telegraph system, a communication circuit comprising two communicating telegraph stations and other stations, and means for selecting any one of said other stations and adding it to the communication, said means controllable from either of said two telegraph stations.

13. In a telegraph system for point-to-point and broadcast messages, a plurality of stations, a single line wire connecting all of said stations, a plurality of selectors one at each station and va riantly adjusted, said selectors adapted each to make its station responsive to telegraphic signals in said single line wire, and a plurality of selectorcontrolling keys, one at each station, said selectors operable successively in any order to make any desired stations concurrently responsive.

14. In a telegraph system, a single line wire, a plurality of stations connected upon said single line wire for selective signaling, a plurality of similar selectors variantly adjusted one at each of said stations, a plurality of further similar selectors similarly adjusted one at each of said stations, 9. signal-sender at one of said stations adapted to send signals over said single line wire to operate either any one of said variantly adjusted selectors or to operate all of said similarly adjusted selectors, and telegraphic apparatus at each 01 said stations and operable only when conditioned by the operation of the selector at its station.

15. In a telegraph system, a single line wire, a plurality of stations connected to said single line wire for signaling, a selective-signal sender at one of said stations, a plurality of selectors one at each station and operable individually and selectively over saidsingle line wire by said sender, a plurality of further selectors one at each station and operable collectively and simultaneously over said single line wire by said sender, telegraphic receiving apparatus at said stations and conditioned by said selectors to be responsive to telegraphic signals over said single wire, and a telegraphic-signal sender at said one of said stations.

tions, telegraph apparatus, motors for driving I said apparatus at said stations, a single line connecting said stations, means including said line for transmitting code combinations .of impulses, and further means responsive to the transmitted code combinations for selecting a station and for starting the motor thereof.

18. In a telegraph system, a plurality of stations, a single line wire connecting all of said stations, a transmitter at one of said stations, means for rendering responsive a number of said stations for telegraphic communication, means at each responsive station for modifying the resistance of said line wire, and a signal at said transmitter and under control of the modified resistance of said line wire for indicating the number of responsive stations.

19. In a telegraph system, a communication circuit comprising a plurality of communicating stations and a single line wire, means for adding a station to said communicating stations and thereby increasing the resistance of said circuit, and a signal device responsive to the resistance of said circuit and indicating the number of communicating stations.

20. In a telegraph system, a calling station, other stations, a communication circuit connecting all said stations, control means at said calling station for including or excluding other stations in said communication selectively, and a signal 40 device indicating how many of said other stations are in communication.

21. In a telegraph system, a single wire, two telegraph stations in communication on said wire, other stations also on said wire, and means for 5 selecting any one of said other stations and adding it to the communication, said means controllable from either of the two telegraph stations.

22. In a" telegraph system, a single wire, two telegraph stations in communication on said wire,

50 other stations also on said wire, normally inert motor means at all said stations, means for selecting any one of said other stations and adding it to the communication by rendering the motor thereat effective.

5s 23. In a party-line teletypewriter system, a plurality of stations capable of being remotely selected successively andautomatically conditioned for concurrent operative teletypewriter communication over a common line between any two or so more of said stations, a driving motor for a teletypewriter apparatus at one of said stations and connections whereby said motor may be started locally only when the code for selecting said station is dialed.

g5 24. A system for teletypewriter communication comprising a plurality of telegraph stations, 9. single line connecting all of said stations, telegraph equipment at all of saidstations including at each station, a selector switch, a dialing device 70 and teletypewriter provided with a motor and a circuit including motor starting contacts, said motor starting contacts being normally in nonmotor operating condition, and a sole means for placing said contacts at any station in motor 75 operating condition consisting of devices controlled by the selector switch local to said station through. appropriate operation of one of said dialing devices, said means operable at a plurality of stations successively to prepare for concurrent intercommunication.

25. In a telegraphsystem, a plurality of receivers, a line connecting all of said receivers at all times, transmitting mechanism connected in said line whereby said transmitting mechanism transmits electrical impulse signals to all of said receivers at all times, means in each receiver for recording said signals, and further means at each receiver for disabling a receiver from recording said signals while continuing to receive said signals.

26. In a telegraph system, a plurality of re-' ceivers, a line connecting all of said receivers at all times, transmitting mechanism connected in said line whereby said transmitting mechanism transmits electrical impulse signals to all of said receivers at all times, means in each receiver for recording said signals, and further means responsive to signals over said line for disabling a receiver from recording said signals while con tinuing to receive said signals.

27. Ina telegraph system, a plurality of receivers having selector magnets, a line connecting all of said receivers at all times, transmitting mechanism connected in said line whereby said transmitting mechanism transmits electrical impulse signals to all of said selector magnets, of said receivers at all times, means for recording said signals, and'further means at each receiver and responsive to signals over said line for dis-= abling a receiver from recording said signals while said selector magnets continue to receive said signals.

28. In a telegraph system, a plurality of re= ceivers having selector magnets, a line connect ing all of said receivers at all times. transmitting mechanism connected in said line whereby said transmitting mechanism transmits electrical impulse signals to all oi said selector magnets oi said receivers at all times, means in each receiver for recording said signals, and further means at each receiver and responsive to signals over said line for disabling a receiver from recording said signals while said selector magnets continue to receive said signals.

29. In a telegraph system, a plurality oi re ceivershaving selector magnets, a line connecting all of said receivers at all times, transmitting mechanism connected in said line whereby said transmitting mechanism transmits electrical impulse signals to all of said selector magnets of said receivers at all times, means in each receiver for recording said signals, and further means responsive to signals over said line for disabling a receiver from recording said signals f while said selector magnets continue to receive said signals.

30 In a telegraph system, a plurality of receivers having selector magnets, a line connecting all of said receivers at all times, transmitting which all of said receivers are connected at all times, transmitting apparatus connected in said line whereby mechanisms of all said receivers are responsive at all times to all signals transmitted by said transmitting apparatus, and means at each or said receivers responsive to signals received from said transmitting apparatus to enable said receivers to print in response to signals received from said transmitting apparatus or to disable said receivers from printing in response to signals received from said transmitting apparatus, said means being operable effectively at one or another of said receivers selectively according to control from said transmitting apparatus 32. In a printingv telegraph system, a plurality of receivers, a linecommon to said receivers to which all of said receivers are connected at all times, transmitting apparatus connected in said line whereby mechanisms of all said receivers are responsive at all times to all signals transmitted by said transmitting apparatus, and means responsive to signals received from said transmitting apparatus to enable said receivers to print in response to signals received from said transmitting apparatus or to disable said receivers from printing in response to signals received from said transmitting apparatus, said means being operable efiectively at one or another of said receivers selectively according to control from said transmitting apparatus. a

33. In a printing telegraph system, a plurality of receivers, a line common to said receivers to which all of said receivers are connected at all times, transmiting apparatus connected in said line whereby mechanisms of all said receivers are responsive at all times to all signals transmitted by said transmitting apparatus, and means responsive to signals received irom said transmitting apparatus to enable said receivers to print in response to signals received from said transmitting apparatus or to disable said re-- ceivers from printing in response to signals received from said transmitting apparatus.

34. In a printing telegraph system, a plurality of receivers, a line common to said receivers to which all of said receivers are connected at all times, a transmitter connected in said line whereby receiving mechanisms of all said receivers are responsive at all times to all signals transmitted by said transmitter, and means responsive to signals received over said line and adapted to enable one oi said receivers to print in response to signals received from said transmitter.

35. In a printing telegraph system, a plurality of receivers, a line common to said receivers to which all or said receivers are connected at all times, a transmitter connected in said line whereby receiving mechanisms of all said receivers are responsive at all times to all signals transmitted by said transmitter, and means responsive to signals received over said'llne and adapted to enable said receivers to print in response to signals received from said transmitter or to disable said receivers from printing in response to signals received from said transmitter, said means being operable effectively at one or another of said receivers selectively according to signals received over said line.

36. In an intercommunicating system, a plurality 01' stations, receiving apparatus at each of said stations, a single-wire circuit connecting all of said stations, means including said circuit for transmitting direct current signal conditions, means responsive to said direct current signal conditions for selecting one or said stations from any one of said stations to automatically condition the receiver at the selected station for operation, means for indicating that one of said stations has been selected for operation, and means including said circuit for operating all selected ones of said stations from. any one of said selected stations.

37. In an intercommunicating system, a plurality of stations, a single signalling circuit connecting all of said stations, means including said signalling circuit for transmitting direct current impulse conditions, means responsive to said im pulse conditions for selecting one or more of said stations, and means operable over said signalling circuit for indicating a response to said means for selecting.

38. In an intercommunicating system, a plurality of stations, a signalling line connecting all of said stations, means including said signalling line for transmitting code combinations of signalling conditions, a receiving printer at each of said stations having a normally inert driving motor, means responsive to said code combinations for selecting said stations, and means individual to each of said printers for automatically starting its motor into operation in response to the selection of its associated station.

39. In a telegraph system, a single line wire,

a plurality of stations connected thereto, means including said single line wire for selecting said stations one by one in any desired order up to any desired number and for conditioning the selected stations for intercommunication over said single line wire, a signal at the selecting station to indicate the response or each selected station, a printing telegraph receiver at each station having a normally inert driving motor, means for starting and stopping the printer-motors at said stations by remote control over said single line wire, the telegraphic apparatus at said stations all combining to form an integral equipment for point-'to-point and broadcast telegraphic messages.

40. In a telegraph system for point-to-point and broadcast messages, a plurality of stations, a single line wire connecting all of said stations, a plurality of selectors at each station and variantly adjusted, said selectors adapted each to make its station responsive to telegraphic signals in said single line wire, and a plurality oi selector-controlling keys, one at each station, said selectors operable at successive stations in any, order to make any desired stations concurrently responsive or operable at all stations simultaneously for broadcasting.

41. In a telegraph system, a plurality of stations, station selector controlling magnets, one at each of said stations, printer controlling magnets, one at each of said stations, line relays, one at each or said stations, a line circuit connected to all of said line relays, a signal impulse transmitter connected in said line circuit to which all of said line relays are at all times responsive, first local circuits, one at eachof said stations, including a printer controlling magnet and a contact of a line relay at each of said stations and responsive at all times to said line relay, second local circuits, one at each of said stations, in-

cluding a station selector controlling magnet and a contact of a line relay at each of said stations and responsive at all times to said relay, and other local circuits at each of said stations and selectively controlled by said selectors and operating selectively to render a station operative.

42. In a telegraph system, a telegraph line, a

plurality of telegraph stations arranged on said line, an automatic switch associated with each of said stations and connected to said line, normally inoperative telegraph transmitting and printingmechanismsat each station connected to said line, number transmitting means at each of said stations, each of said stations having a particular number assigned to it, means responsive to the operation of said number transmitting means in accordance with a particular number from one of said stations for operating the automatic switches on said line at all of said stations, means controlled by the automatic switch of the station to which the transmitted number is assigned for rendering its associated transmitting and printing mechanism. operative, means controlled by the automatic switch of the called telegraph station only for transmitting a cutthrough signal over said line to the calling station, and means in said calling station responsive to said cut-through signal for indicating that the transmitting and printing mechanism at the called station is in operative condition.

43. In a telegraph system, a telegraph line, a

plurality of stations arranged at intervals along said line, an automatic switching device individual to each of said stations and connected to said line; normally inoperative telegraph transmitting and printing mechanisms associated with each of said stations and connected to said line, means at any of said stations for operating all of said automatic switches on said line, the automatic switch at only one of said stations being operative to render its associated telegraph transmitting and printing mechanism operative, an indicating device at each of said stations, means responsive to the operation of the switch rendering its associated telegraph transmitting and printing mechanism operative for operating the indicating device at all of said telegraph stations, and means for telegraphically communicating between the calling and the selected station over said line.

ABRAHAM SUNDAHL BENJAMIN.

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