US2352271A

US2352271A - Teletypewriter pay station circuit

Info

Publication number: US2352271A
Application number: US368838A
Authority: US
Inventors: Wilmarth Y Lang; Fred J Singer
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1940-12-06
Filing date: 1940-12-06
Publication date: 1944-06-27
Anticipated expiration: 1961-06-27

Description

.I une 27, 1944.- A w. Y.` LANG ET AL A l TELETYPEWRITER PAI STATION CIRCUIT 3 Sheets-Sheet l Filed Dec. s, 1940 i WV/ ANGl FJ S/NGER /N VE N TORS' j ATTORNEY June 27, 1944- w. Y. LANG ET Al.

TELETYPEWBITER PAY S'J'JIIOI` CIRCUIT Filed Dec. s, 1940 5 Sheets-Sheetl 2 W y. LANG F J. S/NGE R Y 33m? ATTORNEY i INI/ENTORS! N NNN June 27, 1944- w. Y. LANG E-r AL TELETYPEWRITER PAY sTA'i'IoNIRcUT Filed nec. 6,1940 5 Sheets-sheet s Y WKLANG /NVENTORS-EJ-5/NGER ATTORNEY Patented June 27, 1944 2,352,271 TELETYPEWRITER PAY STATION CIRCUIT Wilmarth Y. Lang, Towaco, N. J., and Fred J. Singer, Rockville Centre, N. Y., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application December 6, 1940, Serial No. 368,838

39 Claims.

' A more specic object of this invention is the provision of teletypewriter circuits whereby teletypewriter service may be made available for typewriter switching oflice by means of loop conductors |02 and |03. The cord circuit per Fig. 2

' is one of a plurality of cords at a particular opgeneral use by the public upon the performance by the user of a certain prerequisite condition, such as the depositing of a coin, etc.

A feature of this invention is a coin collection device connected t`0 a teletypewriter station circuit.

A further feature of this invention is an arrangement Wherein the use of the teletypewriter station facilities for communication may be prevented until a coin is deposited.

A further feature of this invention is an arrangement wherein after communication between a calling and a called party has proceeded, it may c25 be suspended under control of the central station operator until an additional coin is deposited.

These and other features will become apparent from the following description when read with reference to the associated drawings in which:

Fig. 1 is the teletypewriter pay station circuit and station line circuit of this invention;

Fig. 2 is a well-known teletypewriter cord circuit modified to cooperate with the pay station circuit and station line circuit of this invention; and

Fig. 3 is a well-known operators position circuit which cooperates with the cord circuit of Fig. 2.

The operation of the circuits in so far as is necessary to an understanding of the invention herein will now be described.

The drawings are to be arranged as shown in Fig. 4. That is to say, Fig. 2 is to be positioned at the right of Fig. l and Fig. 3 below Fig. 2. The

conductors extending to the bottom margin of Fig. 2 connect to conductors extending to the top margin of Fig. 3 in corresponding positions.

The wiring and apparatus shown at the lefthand side ci Fig. 1 is the teletypewriter pay station circuit. It will be located in some public place to which any one wishing :to make use of pay station teletypewriter equipment has access. The pay station equipment is connected to jack l0! which is located in a switchboard at a teleerators position in the switchboard. The cord circuit is used to interconnect calling and called parties either directly, as in the case of local calls which may be completed in a single switchboard, or through a second switchboard or a number of switchboards in tandem. Fig. 3 is the operators position circuit. One such circuit is furnished per operators position. It may be connected to any of the cord circuits which the operator may be using at any time by the manipulation of a key individual to each of the cords. 'Ihis connects teletypewriter sending and receiving equipment to a particular cord for communication incident to establishing and supervising the connection.

GENERAL DESCRIPTION or PAY STATION CIRCUIT The pay station circuit as shown in Fig. 1 is a loop circuit having its ends terminated in battery and ground at the central station. When the loop isl not in use, it is open at the right-hand outer contacts of relay H0. 'I'he bottom loop conductor, conductor |03, is grounded through the right-hand outer armature and back contact of relay I l0 and the windings of coin collect and return magnets l30 and |3l. The winding of a polar receiving relay, which controls the teletypewriter receiving magnet, and the teletypewriter transmitting contacts are connected in series with the top loop conductor which is open.

' As will become apparent from the detailed description below, the loop may be closed at the pay station by performing two operations, namely (l) inserting a coin in a coin box which closes one set of make contacts |05 in the coin boX, and (2) manually closing the contacts of motor start key 106, which key is located external to the coin box in any convenient position. 'I'hese two sets of contacts are arranged in series to close a shunt around the open right-hand outer contacts of relay H0 where the loop is open. This energizes the left-hand winding of relay H0 which closes the loop.

The coin box which is used in the pay station circuit may be any one of a large variety of multicoin boxes such as that disclosed in the patents to O. F. Forsberg 1,043,219, November 5, 1912, A. F. Bennett 1,863,322, June 14, 1932, and the application of O. A. Shann et al. Serial No. 271,630, iled May 4, 1939, having electrical connections simplied in accordance with the coin box circuit shown in Fig. 1.

As is explained in the disclosures of the abovementioned patents and application, in the operation of multicoin boXes, the coins in dropping through their respective chutes strike bells or metal coils which generate characteristic tones which are picked up by a transmitter. A particulai` coin slot may be arranged so that it strikes a bell once to indicate say the deposit of a ve cent coin. The ten cent slot may be arranged so that the ten cent coin strikes the same bell twice in passing. The twenty-five cent coin will strike a metal coil, or cathedral gong as it is known, to generate a different tone.

The transmitter is arranged in such position with respect to the bell or gong that it can pick up the tone. This results in the generation of a corresponding tone in the receiver at the central station.

The pay station circuit herein is so arranged that the transmitter is normally shunted by contacts IM so that its resistance .is not normally included in the loop circuit. As any coin passes down through its respective slot it opens contacts IM which opens the normally closed shunt around the well-:known transmitter. While the contacts are open and the transmitter is connected in series .in the loop, it vpicks up the tone which is generated by the vstriking of the bell or gong. Then contacts vI I4 are slowly restored to `reclose the shunt.

In the case of the rst coin which is dropped into the slot, .in order to permit the loop to be lclosed when motor start key |06 is actuated, although contacts ||4 are opened to remove the shunt from around the coin tone transmitter as the coin passes contacts IM, since the loop is Vnot yet closed and the operators coin signal receiver is not yet connected to the coin signal jack the operator does not check the coins denomination.

Since it is necessary to deposit a coin in order to close contacts |05, which contacts must be closed in series with motor start key contacts I G6 before the loop can be closed and preliminary to lighting Vline signal lamp |I'Il the central station operator knows that a coin has been deposited.

A coin, after being deposited and closing contacts IE5, is held in suspension for collection or return under control of coin collect and coin return keys in the cord circuit at the central -station whichconnect either positive or negative battery to the ring ofthe loop to actuate either the coin collect or the coin return polarized magnet in the lcoin box -to direct the suspended coin to the coin storage compartment or to the coin return hopper, respectively.

Outward call The manner in which the circuits function on an outward call, that is on a call which originates at the pay station will rst be described.

To originate a call, a coin is inserted in slot 1IIlll of the lcoin box, momentarily opening contacts I I4, which contacts reclose slowlyfand closing contacts |05. Then motor start key |06 is actuated manually momentarily. This closes a circuit which extends from battery at the central office, though the winding of relay |08, break contact and tip jack IllI, pad resistance |09, loop conductor |02, left-hand winding of relay Ht, bottom winding of polar relay II I, teletypewriter sending contacts Il?, left-hand ar mature and break Contact of relay IIS, break contacts H4, make contacts |05, make contacts |05, conductor |03, pad resistance H5, break.

contact and tip of coin signal jack IIS, ring and break contact of jack IUI to ground. Relay H18, at the central oflice, operates lighting lamp as a signal that the pay station is calling. Relay lli) at the station operates and then locks over a circuit from the positive pole of battery IIS, through contacts IIS), which contacts are normally closed, resistance I2B, right-hand winding of relay I I0, right-hand inner make contact and armature of relay IIO to the negative terminal of battery I I8 which is grounded. The operation of relay III) closes a circuit from one side of a source of commercial power supply, preferably alternating current, through the winding of an alternating current relay I2 I, the left-hand outer armature and front contact of relay III! to the opposite side of the power source, operating relay |2l. The operation of relay |2I closes the power supply circuit for the teletypewriter motor (not shown). The operation of relay II shunts its operating winding through the left-hand inner armature and front -contact of relay III),

Polar relay tI I I at lthe pay `station is biased by an obvious circuit through its top winding which maintains the armature of relay lI II in its lefthand position, as shown, while the loop traced above is open. When the loop is closed, the effect of currentin the bottom winding of relay III preponderates over 'the eiect vof the biasing current and the armature lof relay III is actuated to `its right-hand position to engage its marking contact. When the armature of relay III is in engagement withits right-hand contact, the teletypewriter receiving magnet |22 is energized over a circuit `from the positive terminal of battery |23, through the winding of receiving'rnagnet |22, resistance |24, right-hand or marking contact and armature of relay II'I to the negative terminal of battery I 23,

Central station operator 'response 'to line signal In response to the lighting of lamp |I'I in the switchboard at the central station the operator at the particular position where the lamp III and its associated jack |0| are located, inserts plug 2M into jack |0I. 'I'his separates the tip and ring of jack IBI from their associated break contacts. Relay |02! is released, extinguishing lamp .l II. The tip ring and sleeve of the station jack are extended through the tip ring and sleeve of the cord.

Description of cord circuit Except for the modifications necessary to .condition the cord circuit per Fig. 2 to `cooperate with a pay station circuit, the cord circuit per Fig. 2 is well known in the art. It is arranged on one side for answering incoming calls on sub scriber or toll lines. Both the answering and calling cords are arranged to provide an automatic fiashing recall on both toll and subscriber lines. Both cords are arranged to provide a steady disconnect signal. Both cords are arranged to send a recall signal over a connected toll line. The calling cord is arranged to send a disconnect signal over a connected toll line. The calling cord is arranged to ring on a subscriber line or toll line. Ringing on a subscriber line or a toll line to which the answering cord is connected may be accomplished in the operators position circuit. The cordl circuit is equipped with `a single line repeater for repetition of telegraph position circuit.

repeater relays.

lay 208 to ground.

or spacing contact of polar relay 2|2.

Since the operation of the cord is well known, it will be described only so far as is necessary to an understanding ofthe manner in which it cooperates'with the pay station circuit of Fig. 1 to provide pay station service.

In order to cooperate with the pay station circuit, the well-known cord circuit per Fig. 2 has been modified so as to include coin collect and coin return keys in each side of the cord. These keys are indicated as 204, 205,206 and 201. The sleeve circuit may be traced from ground in'Fig. 1 through resistance |25, sleeve of jack |,0|, sleeve of plug 20|, winding of marginal relay 202, winding of relay 203 to battery. The magnitude of resistance |25 is high to prevent the operation of marginal relay 202, which operates only on connection to a toll line, in which the corresponding sleeve resistance is low, Relay 203 operates. The operation of relay 203 operates relay 208 over a circuit from ground through the bottom, armature and front contact of relay 203, through the bottom winding of relay 208 to battery,

,The operation of relay 208 energizes the cord 'contact of relay 208 to ground. A circuit may also be traced from positive battery 2|4, through resistance 2|5, left-hand or marking contact and armature ofY polarrelay 2|2, the bottom or biasing Winding of polar relay 2| l, resistance 2I6 and the top outer armature and front A circuit may be traced from negative battery through resistancev 2|1, bottom inner armature and front contact of relay 208 to the right-hand A circuit may be traced from negative battery through 'resistance 2|8, bottom outer front contact and varmature of relay 208, to the left-hand or spacing contact ofp'olar relay 2| A circuit may be traced from negative battery through resistance 2I1, bottom inner armature and front contact of relay 208, resistance 2I9, top break contacts of the make-before-break contact combination of relay 220, bottom armature andv break contact of key 22|, bottom break contacts of the make-before-break combination of key 222, top Winding of polar relay 2||, armature and left-hand or marking contact of relay 2| 2 and resistance 2|5 to positive battery.

The transmission circuit through the answering `cord may be traced from positive battery 209, through resistance 2|0, right-hand or marking contact and armature of polar relay 2||, top winding of polar relay 2|2, top outer armature and back contact and top inner back contact and armature of relay 223 in parallel, top outer armature and back contact and top inner back contact and armature of relay 224 in parallel, top front contact and armature of relayv 203; top winding of differential relay 221 and resistance 228 to the tip of plug 20|.

contact rof reand break contact of key V205, top armature and back contact of relay 202, bottom winding of differential relay 221, bottom inner armature and front contact of relay 203, bottom outer armature and front contact' of relay 208, and resistance 2 8 to negative battery. H l

It may be observed that the loop remains closed after plug 20| is inserted in jack 0|. Positive battery |01. connected to the tip of the subscribers loop through jack |0| is'replaced by positive battery connected to the markingcontact of relay 2||. Ground connected to the ring'of the subscribers loop through jack |0|, is placed by negative battery connected to resistance 2l8. The polarity of the current through the loop remains the same as before'the insertion of plug 20|.

The effect of the current through the bottom or biasing windings of polar relays 2|| and 2|2 in the paths traced above is to tend to actuate the' armatures of these relays to engage with their respective spacing contacts,Y This effect is opposed in each instance by the effect f the current in the top or line windings of these relays in the paths traced above, which latter eiect preponderates and` the armatures are actuated to engage with their marking contacts with which each is shown in engagement in Fig.2. The ef`- fects of the current inthe top and bottom windings of differential relay 221 neutralize each other so thearmatures remain unoperated as'shown in Fig. 2. l

Operators position circuit connected to cord.

The operator will connect her position circuit to the cord in order to communicate with vthe calling party. This may bedone before the cord is connected to the calling line or after such connection. To perform this operation the operator actuates key 225. This connects ground through the middle armature and front contact ofkey 225, and the winding of relay 224 to battery, operating relay 224. The operation of relay 224 Yconnects the transmission loop lin the operatorfs position--circuit in series with'the cord circuit Atransmission loop heretofore traced. The position circuit loop is' cut in at the two top makebefore-break contact'combinations of relay224.

'The operators loop may be tracedfrom the top outer make contacts of the make-before-break contact combination of relay 224,'l through the top break contacts of the make-before-break contact combination of key 30| in parallel with the bottom break contacts of the bottom make-be- -fore-break contact-combination of key 30|, top

lnow extends through all of the circuits, namely,

the Day Station line and station circuit, the cord circuit and the operators position circuit. The armature of `relay 305 is shown in engagement with its' right-hand or spacing contact. The eiect of the current in theV bottomv winding, when the circuits are interconnected and current flows for the marking'condition, is to operate the armature of relay 305 to engage with its left-hand or marking contact. Key 306 is operated. This establishes a path for energizing the top or biasing winding of relay 305, which path may be traced from battery through resistances 3II and 301, top winding of relay 305 and the top armature and make contact of key 306 to ground. The effect of current in this path returns the armature of relay 305 to its righthand or spacing contact when the loop is opened either at the transmitting contacts in the station circuit or at the transmitting contacts in the operators position circuit as well as when the armature of relay 2li is actuated to engage with its left-hand or spacing contact, in response to a spacing signal received from the circuit to which the calling end of the cord is connected. Under this latter condition both ends of the loop which extend through the bottom winding of relay 305 are connected to negative battery and the loop current drops to zero.`

With key 305 operated, when relay 305 is in its left-hand or marking contact, the winding of relay 309 is energized from ground through the top make contact and armature of relay 306, winding of relay 309, resistances 308 and 3II to battery. When the armature of relay 305 is engaged with its right-hand or spacing contact, the winding of relay 309 is shunted by the path through the armature and right-hand or spacing contact of relay 305 but relay 309 remains operated during the reception of ordinary communication signals, as relay 309 is a slow-release relay. Its function is to prevent the teletypewriter from spinning during long idle intervals. In order to do this it is necessady to maintain the receiving magnet 3|0 energized during such intervals. During the reception of ordinary marking and spacing signals, the receiving magnet 3 I 0 is energized :for marking and deenergized for spacing signals. The circuit by means of which magnet 3|0 is energized during marking may be traced from battery through resistance 3I2, winding of receiving magnet 3|0, resistance 3I3, make contacts of the make-before-break contact combination of relay 300, which is operated, left-,hand or marking contact and armature of relay 305 and through the top armature and make contact of key 306 to ground. When the armature of relay 305 is actuated to engage with its right-hand or spacing contact, this path is broken and magnet 3|0 is deenergized. Relay 309 does not release on ordinary spacing signals. For long spacing signals relay 309 releases, closing an energizing path for magnet 3|0 through its break contacts to ground on the bottom armature and make contact of key 306.

Calling party and operator communicate The calling party operates the teletypewriter at the pay station to transmit the number of the called party. This is recorded on the teletypewriter receiver in the operators position circuit as magnet 3|0 follows the signals.

Operator extends the call The next step in the proceedings is the eXtension of the circuits toward the called party. If the call is a local call, it may be completed in the same switchboard as the one in which the calling pay station line is terminated. If the call is to a station in a distant city it will be extended to a switchboard in the distant city for completion by means of a long distance circuit extending to the switchboard in the distant city.

The operator will connect her position circuit to the calling end of the cord by operating key 30I. This connects her transmitter and the bottom winding of the receiving relay 305 in series with the cord repeater. This circuit may be traced from battery in Fig. 3 through resistance 3I4, bottom armature and make contact of key 30|, top armature and break contact of key 302, break contacts of key 303, bottom winding of receiving relay 305, transmitting contacts, break contacts of key 304 to the top inner make contacts of relay 224 from whence the circuit has been traced to positive battery 209.

Positive battery is conected to the tip conductor of the station loop simultaneously to hold the loop closed. The circuit for this may be traced from positive battery in Fig. 3 through resistance 3I2, the middle armature and front contact of key 30| to the top outer make contacts of the make-before-break contact combination of relay 224. From this point the circuit extends over the tip around the station loop and back on the ring to negative battery connected to resistance 2I8 in Fig. 2.

The operator inserts the plug of thev calling cord 230 into the jack 23| connected to the called line or to a trunk extending to the proper distant city.

If the connection is made directly to a subscribers line, ground through a relatively high resistance 232, approximately 600 ohms, is connected, in the sleeve of the called lineto the circuit which extends through the windings of Vmarginal relay 233 and relay 220. vRelay 220 operates. Relay 233 remains unoperated as it is arranged to respond only when connected to a trunk circuit having a lower sleeve resistance.

The operation of relay 220 connects the tip of the calling cord to the cord.circuit repeater. This circuit may be traced from the tip of plug 230 through resistance 231, top winding of differential relay 234, top armature and front contact of relay 220 to a circuit which has been traced from this point to positive battery 2I4.

It will be assumed that the cord circuit per Fig. 2 vis connected to a regular subscribers line indicated by a rectangular box 24 I This regular subscribers line is not arranged for pay station service. l

In a well-known line circuit of such type, while the line is idle, the line conductor which conlnects to the tip of the cord is connected to ground through a condenser and ringen The other line conductor, which connects to the ring, is connected directly to ground.

From ground on thering of the regular subscribers line (not shown) the circuit extends through the 4ring of jack 23 I, armature and break contact of key 205, armature and break contact of key 20T, top armature andbreakcontact of relay 233, bottom winding of diferential relay 234, bottom inner armature and front contact of relay 220, bottom inner make Vcontact and armature of relay 208 and resistance 2I1 to negative battery. Relay 234 operates. This lights the calling cord supervisory lamp 235 over a circuit from ground through the armature and front contact v'of relay 234, filament of lamp 235v to battery through the night alarm circuit. It also operates relay 242 in parallel with the lamp through the top winding of relay 242 to battery through the bottom inner armature and back contact of relay 233. The operation of relay 242 closes a circuit from negative battery through resistance 2 I1, bottom inner armature and front contact of relay 203, resistance 2I9, top armature and front contact of relay 242 to the calling side of the repeater to hold it closed. The operation of relay 234 also prepares a circuit for the operation of relay 236 from ground through its upper front contact and armature, through the Winding of relay 236 to the top armature to key 22|.

Operator rings called party The operator now rings the called party by operating key 2||. The operation of key 22| operates relay 236, opens the tip lead and connects the calling side of the repeater to negative battery through resistance 2 through the make contacts of the make-before-break combination of key 22|. v

The operation of relay 236 locks the relay over a path from battery, through the front contact and top armature of relay 236, winding of relay 236, and through the top armature and front contact of relay 234 to ground. The operation of relay 236 closes a circuit' from battery through the bottom front contact and armature of relay 236 and the Winding of relay 238, to ground, operating relay 238. The operation of relay 238 releases relay 242 and transfers the holding path for the calling side of the cord repeater from the contacts of relay 242 to corresponding contacts on relay 238. The operation of relay 238 applies ringing to the tip of the cord and its connected station loop conductor over a circuitV from a grounded source of alternating current 239, through the filament of lamp 240, bottom front contact and armature of relay 238 and the bottom front contact and armature of key 22| to the 'tip of the cord over a circuit heretofore traced.

'Ihis current passes over the tip conductor of the station loop and through a condenser and ringer to ground operating the ringer. In response to this the called party will operate his station loop and power switch which disconnects the ringer, closes the loop and connects power to his station teletypewriter so that the station equipment is conditioned to communicate with the calling party. The response of the called party by connecting the tip and ring loop conductors together will cause current to pass through both the upper and lower windings of dilerentially wound relay 234. This will release the armature and extinguish the calling supervisory lamp 235. It will also release relay 236 which was locked to ground on the top front contact of relay 236. This in turn will release relay 238 to disconnect the ringing current. The transmitting contacts and the winding of the receiving magnet at the called station are connected in series in the station loop and the station is ready for communication.

Operator communicates with calling party regarding tariff After the operator has rung the called party, while waiting for the called party to respond, she will disconnect her position circuit from the calling side of the cord and connect it to the answering' side of the cord. She then requests the calling party to deposit coins in the necessary amount, depending on the tariff, andv plugs her receiving device into coin signal jack I6 so that she may check the denomination and number of the coins as they are deposited in a well-known manner.

In order to connect her position circuit to the answering Vend-of the cord, the operator releases key 30| and-actuates key 304. This. will connect contacts to the tip of the cord circuit.

4type -Time up. VDeposit tacts |26.

negative battery to the repeater in the cord circuit to maintain it in the closed or marking condition. The circuit may be traced from negative battery in Fig. 3 through resistance 3|4', middle armature and front contact of key 3&4 to the top inner make contacts of the make-beforebreak combination of relay 224, Where it connects to a path, which has heretofore been traced in detail, to positive battery 200 connected to the marking contact of polar relay 2||. The operation of key 304 also connects positive battery in the operators position circuit through the operators receiving relay and transmitting This circuit may be traced from positive battery through resistance 3|2, the bottom armature and front contact of key 304, the sending contacts of the operators teletypewriter, bottom winding of relay 305, front contact and armature of key 303, upper break contact and armature of key 302, upper break contact and armature of key 30|, to the make contacts of the top outer makebefore-break combination of relay 224 in Fig. `2, from which point the circuit has heretofore been traced over the tip, around the station loop and back on the ring to its termination in negative battery connected to resistance 2|8.

The operator types the amount of the tariff for the particular call, which is recorded on the station teletype receiver. She then listens by means of her audible receiver 232 which is connected to jack ||6. v Each coin which is deposited causes a characteristic tone to be transmitted over the circuit and through resistance 232 which actuates the receiver. Thus the operator may identify the number and denomination of the deposited coins which pass'contacts |05 at the station.

Calling and called parties communicate After the operator has checked to insure that the proper amount has been deposited, she withdraws her audible receiving device 232 from jack ||6. She also restores her splitting key 304, by means of which her position circuit was connected to the calling subscriber, to normal. The operator also restores key 225 to normal to disconnect her position circuit from the cord. The calling and called parties then communicate.

If the operator hasoccasion to answer a. call on another line, she actulates a key-corresponding to key 225 in another cord which connects her position circuit to the other cord andproceeds as described above.

Operator intervenes ori overtime call 1f the calling and called parties communicate for longer than the interval permitted for the amount deposited, the operator will again reconnect her position circuit to the calling. partys loop by actuating key 225 in the original cord and key 304 in the position circuit. The operatcrwill for additional minutes. The operator will then send out a particular upper case signal, such as an upper case S. In response to the reception of the vcorresponding train of signal elements by the teletypewriter receiving magnet |22, the teletypewriter receiving mechanism instead of makingja selection which prints a letter, makes a selection which operates a mechanism which performs a function in a well-known manner.` 'The function which is performed is the closing of con- This closes a circuit from .battery vthrough resistance |21, left-handwinding of relay II3 and contacts |26 to ground, operating relay I|3.

The operation of relay I I3 at its left-hand outer armature and front contact closes a shunt around the armature and marking contact of relay III to maintain the station receiving magnet |22 energized so that it no longer may follow relay I I I. This prevents the reception of further signals. At the left-hand inner transfer contacts of relay II3, the loop path through the sending contacts is shunted by a path which extends from point |28 through the left-hand inner front contact and armature of relay ||3 and then in series through the right-hand armature, front contact and locking winding of relay II3. Relay |I3 is arranged so that its right-hand armature and associated front contact close before the left-hand inner armature breaks from its back contact to prevent the opening of the loop.

When the right-hand winding of relay ||3 is L,

connected in series with the loop, relay I3 locks up, as the loop is continuous and positive battery is connected to one end and negative battery is connected to the other end at the central station. Contact |26 reopens automatically in a wellknown manner, after relay I |3 locks, as the teletypewriter receiving mechanism completes the cycle of operations in response to the upper case signal by which the contacts were closed. The shunting of the station teletypewriter sending contacts prevents any further transmission from the pay station until additional coins are deposited.

The operator reconnects her audible receiver 232 to the coin signal jack IIB and checks the deposit of the additional coin or coins by noting the number and pitch of the tones received as the coins are deposited.

After the correct amount has been deposited the operator opens the line momentarily, which permits relay I|3 `to release. This removes the shunts from :around the contacts of the station circuit receiving relay III as well as that around the station transmitting contacts I I2 and the calling and called .parties may thereupon resume communication.

Recall Either station attendant may recall the operator. The attendant at the called station which does not include -pay station equipment actuates a power switch to open the called station loop. This opens the tip and grounds the ring. The attendant then recloses the loop. In the case of the calling pay station, the attendant at the station transmits an upper case H as described above which opens the ltip of the loop and grounds the ring. Then the attendant at the pay station immediately reoperates motor start key |06 to close the shimt around the open loop contacts of relay I |0. It should be remembered that contacts |05 are maintained closed by the suspended coin or coins. Relay ||0 reoperates, reclosing the loop.

In response to opening. the loop momentarily, the diierential relay in the corresponding end of the cord circuit, such as relay 221 will operate as described above vfor the disconnect operation. Simultaneously relay 240 will operate over a circuit from ground through the bottom armature andiront contact of relay '221, the-bottom inner armature and back cont-'act of marginal relay 202, which is released, through the bottom winding of relay 246 to battery. Relay 246 .operates and locks over a circuit from battery through the top winding, top front'contact and armature'of relay 246, bottom outer armature and back contact'of relay 224, which relay is released, bottom outer armature and back contact of relay 223, which is also released, to ground through the bottom armature and iront contact of relay 203, which is operated over the sleeve circuit of the cord, which is still connected to jack I0 When differential relay 221 releases, on the reestablishing of the station loop circuit, the lamp circuit which has been controlled from the steady ground at relay 221 is flashed from interrupted ground through the bottom armature and front contact of relay 24B and the bottom inner back contact and armature of relay 202.

The supervisory lamp associated with the calling end of the cord is flashed over a corresponding circuit associated with the calling end of the cord in a similar manner on a recall from the called party.

Disconnect Upon completion of the call the calling subscriber transmits a disconnect signal to light the supervisory lamp in the answering end of the cord. This is performed in the following manner.

The calling subscriber operates the teletypewriter transmitter to send an upper case H signal. This signal will operate receiving relay III at the calling subscribers own station. The train of signals corresponding to the upper case H will cause the teletypewriter receiving mechanism controlled by receiving magnet |22 to make a selection which results in the actuation o a functional lever in a well-known manner. The functional lever in turn will open contacts IIS. This in turn will deenergize the right-hand or locking winding of relay ||0. Relay I|0 releases. This will reopen the station loop at the righthand outer contacts of relay I I0. When the loop is opened, as the right-hand outer armature of relay IIO engages its back contact, the ring of the loop is grounded through the windings of the coin collect and coin return relays. This energizes the bottom winding of differential relay 221 which lights the supervisory lamp in the answering end of the cord. The circuit for this may be traced from ground, through the bottom armature and front contact o relay 221, filament of the supervisory lamp'245 to battery through the night alarm circuit.

The supervisory lamp 235 associated with the calling end of the cord will be lighted when the called party disconnects in a similar manner by a corresponding circuit associated with the calling end of the cord.

After the calling party has disconnected, the operator at the central station may collect or return the depositedgcoins which have been held 1n suspension during the proceedings described above, by operating either key 204 or key 205. Key 2,04 supplies ,positive battery over the ring through the windings of polarized coin collect and coin return relays |30 and |3|. Key 205 supplies negative battery Yto the same circuit. The windings of the relays are so poled that one responds to positive battery and is unaffected by negative battery while 'the other responds to negative battery and .is -unaiected by positive battery. By actuating .the `proper key the operator at the central station may operate veither relay to collect or .return the coins as required.

Operator disconnects cord After the operator vhas collected or returned the coins, she disconnects the cord circuit from the jacks with which'it is connected. This ex- Inward call The circuit per Fig. 1 may serve as the called station circuit. In such cases the operatorat the central station will connect the plug 230 associated with the calling end of her cord into a jack such as Illl and operate the ringing key in the calling cord in the same manner as described above. The ringing current will pass over the tip of the station loop through the left-hand inner armature and back contact of relay Il!) through condenser l32 and ringer |33 which are connected in series across the pay station top loop conductor operating the ringer. In response to this the called party will deposit a coin in the coin box at the called station to close contacts |05 so that the called pay station may be closed in the manner described above by thereafter momentarily operating motor start key |06 to operate relay l I0 which closes the called station loop.

At the conclusion of the call, when relay llll in the called partys loop has been released, the operator will return the coin to the called party isn the same manner as described above by operating the coin return key associated with the calling end of the cord.

What is claimed is:

l. In a teletypewriter switching system, a teletypewriter station circuit, a first means therein responsive to the depositing of a coin in a coin collection device in said circuit for signaling a central station and a second means therein, independent of said rst means, for generating direct current telegraph signals.

2. In a teletypewriter Switching system, a central teletypewriter switching station, a local teletypewriter station, ateletypewriter transmitter and receiver at each of said stations, means in said system for establishing a continuous direct current telegraph p-ath connecting said teletypewriters, a calling Signal independent of said teletypewriters fory attracting an o-perators attention to said path at said central station, a coin collection device connected to said path at said local station and means at said local station-responsive to the insertion of a coin in said device for operatingsaid signal.

3. In a teletypewriter switchingfsystern, a central teletypewriter station, avlocal teletypewriter station, a telegraph path arranged for the transmission of direct current telegraphrsignals connecting said stations, teletypewriter means at each of said stations for communicating over said path, a coin collection device connected'v to said path at said local station and means at said central station for discriminating between `the denomination of coins inserted in said device.

4. In a teletypewriter switching system, a central teletypewriter station, aflocal teletypewriter station, a direct current telegraph path connecting said stations, teletypewriter means at leach of said stations for communicating over saidvpath, a coin collection device connected to said path at said local station and means at said central station for indicating the number of coins ywhich are inserted in said device.,v

5. In a teletypewriter switching system, a centralteletypewriter station, a local teletypewriter station, a direct current telegraph path connecting said stations, teletypewriter means at each of said stations for communicating over said path, a coin collection device connected to said path at 'said local station and means connected to said path responsive to the insertion of a coin in said device for operating a line calling signal at said central station independent of said teletypewriter at said central station.

6. In a telegraph system, a local teletypewriter station, a central teletypewriter station, a telegraph path connecting said stations, telegraph transmitting and receiving means connected to said path for communicating over said path by means of direct current and no current signal impulses and means at said central station for preventing further communication over said path after communication over said path has been established until additional coins have been deposited in a collection device at said local station.

7. In a telegraph system in combination, a rst and a second local telegraph station, a central telegraph station, telegraph means for establishing a continuous electrical telegraph path between teletypewriters connected to said path at each of said local stations, said path extending through said central station and a coin collection device connected to said path at said rst local station responsive to control means at said central station for regulating communication between said local stations.

8. In a teletypewriter switching system, a pay station teletypewriter circuit at a first local station, a teletypewriter cord circuit at a central teletypewriter switching station, a teletypewriter station circuit at a second local station, an operable telegraph path interconnecting said circuits, teletypewriter connected to said path at each of said stations and means in said circuits for controlling communication over said circuits responsive to the prepayment of established charges for individual calls.

9. In a teletypewriter switching system, a local teletypewriter station, a teletypewriter thereat connected to a central teletypewriter switching station by means of a continuous electrical telegraph path arranged for the transmission of direct current telegraph signals, means at said central station for checking the deposit of coins in a coin collection device at said local station and means, including a teletypewriter cord circuit, for extending said path toward a called teletypewriter station.

1G. In a teletypewriter switching system, in combination, a pay station telegraph circuit, a iii-st means in said circuit for generating direct current telegraph signals and a second means in said circuit for generating individual signals to characterize coins of different denominations.

l1. In a teletypewriter switching system, in combination, a pay station teletypewriter circuit including a teletypewriter transmitter, a teletypewriter receiver and a coin box, means dependent upon the depositing of a coin in said box for conditioning said circuit for communication and means responsive to the operation of said receiver for preventing further communication from said transmitter until an additional coin is deposited.

12. In a teletypewriter switching system, in combination, a prepayment teletypewriter station circuit at a local teletypewriter station connected to a teletypewriter line circuit at a central teletypewriter s-witching station, means for transmitting impulses of direct current between said stations as telegraph signals and means for transmitting an alternating current between said stations to denote the depositing of a coin.

" 13. A system in accordance with claim l2 including in combination a signal connected to said line circuit at said central station for indicating that said local station is calling.

14. A system in accordance with claim 12 including in combination a teletypewriter cord circuit for responding to a call from said local station.

15. A system in accordance with claim 12 including, in combination, a teletypewriter cord circuit and an operators teletypewriter position circuit comprising a teletypewriter transmitter and receiver for communicating between said local station and said central station.

16. A system in accordance with claim 12 including, in combination, means at said central station for checking the denomination of coins and the number of coins deposited in a coin collection device at said local station.

17. A system in accordance with claim 12 including, in combination, control means at said central station for controlling the return of coins deposited in a coin box at said local station.

18. A system in accordance with claim 12 including, in combination, coin collection control meansfor controlling the collection of coins deposited in a coin box at said local station.

19. A system in accordance with claim 12 including, in combination, communication control means for suspending communication to or from said local station, after communication has been established, until additional coins have been deposited in a coin box at said local station.

20. In a teletypewriter switching system, in combination, a prepayment local teletypewriter station circuit connected to a central teletypewriter switching station, means, including a teletypewriter, at said central station for extending a telegraph path, arranged for the transmission of direct current telegraph signals, from said local station toward a second telegraph station and means in said extension means responsive t control means at said local station for recalling an operators attention to said path.

21. In a teletypewriter switching system, a subscribers teletypewriter station circuit, a teletypewriter therein, means in said circuit for transmitting and receiving telegraph signals and means in said circuit for preventing the operation of said teletypewriter until after a coin has been deposited in a coin collection device connected directly t0 said teletypewriter in said circuit.

22. In a teletypewriter switching system, in combination, a subscribers teletypewriter station circuit including a coin collection device, a direct current telegraph loop circuit connecting transmitting contacts on a teletypewriter in said station circuit directly to a central teletypewriter switching station and a flexible link at said central station for extending said circuits to a distant station.

23. In a teletypewriter switching system, a rst and a second teletypewriter station circuit, a teletypewriter machine in each of said circuits, a continuous direct current telegraph path arranged for two-way teletypewriter communication interconnecting rsai-l machines, a coin collection device connected in said station circuit at one of said stations and means connected to said path for controlling communication over said path in response to the depositing of a coin in said device.

24. In a teletypewriter Yswitching system, a local teletypewriter station, a central teletypewriter switching station, a teletypewriter machine at each of said stations, a continuous direct current telegraph path interconnecting said machines. a coin collection device connected to said path at said local station, means in said path responsive to the depositing of a coin in said device for controlling communication over said path, and means at said central station, independent of said teletypewriter thereat, for identifying coinsdeposited in said device.

25. In a teletypewriter switching system, a local teletypewriter station, a central teletypewriter switching station, a teletypewriter transmitter at said local station, a coin collection device at said local station, means responsive to the actuation of said device for establishing a continuous electrical telegraph path interconnecting said transmitter and said central station a line calling signal at said central station responsive to the establishment of said path, a teletypewriter transmitting and receiving machine at said central station and a cord circuit at said central station for connecting said machine to said path.

26. In a teletypewriter switching system, a local teletypewriter station, a central teletypewriter switching station, a teletypewriter transmitting and receiving device at each of said stations, a coin collection device at said local station, means for establishing a continuous direct current telegraph path directly connecting said machines dependent upon the depositing of a coin in said device and means res-ponsive to the transmission of telegraph impulses from said switching station to said local station for preventing transmission from said local station until an additional coin is deposited in said device.

27. In a teletypewriter switching system, a rst and a second teletypewriter station, a coin collection device at one of said stations, a teletype- Writer transmitting and receiving device at each of said stations, means responsive to the depositing of a coin in said device for establishing a continuous direct current, two-way telegraph path directly interconnecting said machines.

28. In a teletypewriter switching system, a rst and a second teletypewriter local station, a central teletypewriter switching station intermediate said stations, teletypewriter transmitting and receiving machines at each of said stations, a coin collection device at one of said local stations and means at said stations for establishing a continuous direct current, two-way telegraph path extending through said machines dependent on the depositing of a coin in said device.

29. In a telegraph switching system, a local teletypewriter station, a central teletypewriter switching station, a teletypewriter transmitter and receiver a each of said stations, a teletypewriter station circuit at said local station, a teletypewriter line circuit, a teletypewriter cord' circuit and a teletypewriter position circuit at said central station, a coin collection device connected to said station circuit at said local station and means, dependent upon the depositing of a coin vin-said device, for establishing a continuous direct current telegraph path between said teletypewriter transmitters and receivers through said circuits.

30. In a teletypewriter switching system, a teletypewriter cord circuit, a teletypewriter transmitter and receiver directly connected to said cord circuit and means connected to said cord circuit for controlling the operation of a coin collection device also connected to said cord circuit by means of an operable direct current telegraph circuit.

31. In a teletypewriter switching system, a teletypewriter cord circuit, a teletypewriter opera,.- tors position circuit including a teletypewriter transmitter and receiver connected to said cord circuit and-a coin collection control device in one of said circuits.

32. In a teletypewriter switching system, a teletypewriter cord circuit including a telegraph repeater, means for selectively associating a teletypewriter position circuit including a teletype- Writer transmitter and receiver with said cord circuit and coin collection and return controlling means connected to said circuits.

33. In a teletypewriter switching system, a central teletypewriter switching station, a teletypef writer receiver thereat and coin collection controlling means connected to said receiver.

34. In a teletypewriter switching system, a local teletypewriter station, a central teletypewriter switching station, a teletypewriter transmitter and receiver at each of said stations, a coin collection device at said local station, telegraph circuit means for interconnecting said transmitters and receivers, means dependent upon the depositing of a coin in said device for operating a line calling signal at said central station and means, separate from said signal and from said transmitter and receiver at said central station, for identifying coins deposited in said device.

35. In a teletypewriter switching system, a teletypewriter local station, a teletypewriter central switching station, a telegraph path interconnecting said stations, telegraph means connected to said path for communicating between said stations, a coin collection device connected to said path at said local station and means at said central station for returning a coin deposited in said device.

36. In a teletypewriter switching system, a first and a second telegraph station, a continuous electrical telegraph path interconnecting said stations, telegraph means for communicating between said stations and means at one of said stations for controlling a coin deposited in a coin collection device connected to said path at the other of said stations.

37. In a teletypewriter switching system, a local telegraph station, a central teletypewriter switching station, a telegraph transmitter at one of said stations and a telegraph receiver at the other of said stations, a continuous electrical telegraph path interconnecting said transmitter and said receiver, a coin collection device connected to said path at one of said stations and a coin collection control means connected to said path at the other of said stations.

38. In a teletypewriter switching system, a rst and a second local teletypewriter station, a central teletypewriter switching station, a teletypewriter trans-mitter and a teletypewriter receiver at each of said stations, means including said teletypewriter transmitter and receiver at said central switching station for establishing a continuous electrical telegraph path interconnecting said teletypewriter transmitters and receivers at said local stations and means at said central station for controlling communication over said path depending upon the prepayment of charges for individual calls.

39. In a teletypewriter switching system, a local teletypewriter station, a central teletypewriter switching station, telegraph communication means at each of said stations, a coin collection device at said local station, means for establishing a continuous, electrical telegraph path interconnecting said communication means at each of said stations, a coin collection device connected to said path at said local station, means for characterizing the denomination of coins deposited in said device at said local station and means for discriminating between the characterizations at said central station.

WILMARTH Y. LANG. FRED J. SINGER.