US1491337A - Coin-collect system for automatic telephone exchanges - Google Patents

Description

- R. D. CONWAY Y COIN COLLECT SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES Filed Aug. 11. 1920 2 Sheets-Sheet' l April} 22 1924., 1,491,337

R. D. CONWAY COIN GOLLECTSYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES Filed Aug. 11. 1920 2 Sheets-Sheet 2 to-be permanently shunted by a direct Patented Apr. 22, 1924.

UNITED STATES.

PATENT. OFFICE.

ROY noueras CONWAY, or CHATHAM. New JERSEY, ASSIGNOR T0 WESTERN ELEG- zrnrc COMPANY, INCORPORATED, or NEW YORK, N. Y. A CORPORATION or NEW YORK. O

COIN-COLIJECT SYSTEM FOR AUTOMATIC TELEPHONE'EXGHANGESP Application filed August 11, 1920. Serial No. 402,760.

T 0 all whom it may concern:

Be it known that I, ROY D. CONWAY, a citizen of United States, residing at-Chatham. inthe county of Morris, State of- New Jersey. have invented certain new and useful Improvements in Coin-Collect Systems for Automatic Telephone Exchanges, of which the following is a full, clear, concise, and exact description. 1 i

This invention relates to machine switching telephone systems with subscribers control wherein coin collectors are provided at the substations. p a 1 Its object is to provide an improved circuit arrangement for systems of this type which shall be positive and efficient in operation; One feature of this invention is the provision of improved means for preventing a calling party from building up a connection until he has depositeda coin in the coin box. In accordance with this feature, a marginal relay is provided-at the central oltice which does not operate upon the mere closure of the loop by the removal of the receiver at the calling station, but only operates due to a circuit change which is caused by the deposit of a coin in the coin box. In the present embodiment this relay is included in a circuit including the free pole of the battery at the central ottice oneside of the line, the substation loop, the other side of the-line and a high resistance at the central ottice to ground. When the ground branch is closedat the calling substation by the deposit of the coin, this hioh resistance return is shunted and the marginal relay thereupon operates. In operating it connects the impulse relay to the one side ofthe calling line and causes said high resistance in the otheriside ground return. This impulse relay in operating closes a bridge of the talking conductors to and including the impulse relay of the first selector. Thus the steppingv mechanism of the first selector is placed under control ofth calling subscribers dial, who may now proceed to build up his connection.

The present circuit arrangement makes.

possible the employment in pure automatic working of the coin box shown in Forsberg Patent No. 1,043,219 dated. Nov. 5,. 1312 whichis now'ingeneral and successful use in manual working in the Belhsystem, with-' out changing the design of the coin box in any way.

Coin collect circu1t arrangements are known wherein the calling party cannot build upa connection without depositing a coin in the box, but in these systems, additional contacts had to be provided in the coin'bo'xto short circuit the sender impulse springs. It is desirable from an operating standpoint to reduce the work the coin must do as far as possible. The work the weight of a ten cent piece can do for example is very small. This c0111, however, satlstactorily operates the springs of the coin boX patent referred to. I

'Another featureconsists in the provision of improved means for preventing the discharge of the condensers in the connecting circuit from interfering with the character of the impulses transmitted to the stepping magnets of the switches.

A further feature relates to the provision of a circuit arrangement for systems of the character which will take care of free calls as well asordinary calls.

Another feature consists in the provision ota circuit arrangement for pure automatic working wherein the deposit of the coin connects the polarized magnet/in the coin box to ground, for preventing this groundfrom holding up the release of the switches when the subscribers replace their receivers Referring to the drawings Fig. 1 shows a calling line, ar1ine switch and the coin control circuit; Fig. 2 shows a secondary line switch, a first selector, a. connector and the called line. Y i

The invention will be most readily understood from a detailed description of the operations involved in setting up a connection.

Upon the removal of the receiver at the calling substation, the relay 101 of the primary line switch PLS individual to the calling line is operated over the calling line circuit. In attractirg its armature it closes a circuitincluding the pull down winding 102 of the line switch which causes the line switch to seize the preselected trunk by operating the set of springs in the Well known manner; as shown and particularly described for example in Patent No. 130L369, to A. J. Ray of May 20, 1919. The calling line is now extended to the trunk circuit, I

free pole of battery, contact 104 of relay Y,

conductor 105, contact 106 of relay S, oonductor 107, contact 108 of relay N N, resistance 187, conductors 109, 110, the inner I right armature and back contact of relay v conductor '164, including springs 166, 167

of the line switch, upper armature and back contact of relay A, left armature and 'back contactof relay B, retardation coil 188, relay L, outer left armature and back contactof relay N N to ground. Relay L closes a 0 circuit for the cut-off winding is as follows:

circuit for the cut-off winding 103 of the line switch to holdthe line switch set before the circuit for the pull down winding 102 is opened as the line relay 101 releases. The

ground, left armature and front contact of relay L, conductor 131, outer right armature and back contact of relay H H, conductor 199, contact 198 of relay N N, conductor 146, release or sleeve conductor 125,.

springs 112 113, cut-off winding 103, free pole of battery. I

When the primary line switch PLS operated and closed springs 114, '115 the following circuit-was closed to operate the sec-;

ondary line switch SLS to seize an idle first selector; grounded spring 115, spring 114, secondary line switch holding conductor I 116, outer left armature I and back contact l of relay H H, conductor 11.7, conductors 201,

202, pull down coil 203 of the secondary line switch, contact 204, conductor '205, slow re lay 206, to free pole of battery. The secondary'line switch SLS inoperating closes a locking circuit for itself, including its windings 207, 203 in seriesand contact .208, to grounded holding conductor 201.

Relay L, in.- attracting its left armature, operates slow to release relay N, which operts relay N N. Relay N N in attracting /its outer left armature removes the shunt from about the high resistance 118-gfor a purpose which will shortly appear, and in attracting its inner left armature grounds the release conductor 125 over conductor 146 to hold up the primary switch PLS after relay L releases.

Relay N N in attracting itsinner right armature at 108 substitutes relay RT for well-known manner.

The coin box may be of the type a shunt about relay L and the high resistance 118, whereupon the marginal relay RT operates over a circuit including the ring side of the line l65, the calling substation receiver hook, and the ground closed by contact120 of the coin box.

vRelay RT in operating, energizes relay S over the following circuit: battery, armature and front contact of relay RT, conductor 121, relay S, conductors 122, 123,

outerleft -armature and front contact of relay N N to ground. In attracting its opens the circuit of relay N which is slow tourele'ase. In attracting its inner left armature, relay S connects the impulse relay In at- R"to the ring side 165 of the line. tracting its inner right armature it removes relay RT from the calling. line circuit and lockssitself to grounded battery at a normal contact of relay Y'andtothe 'rounded sleeve or release conductor 124. This conductor was grounded. when the secondary line swi-tch'seized the first selector in the The locking circuit of relay S is as follows: free pole of battery contact 104 of relay Y, conductor 105, inner right, armature and front contact of relay S, relay S, conductor122, grounded sleeve wire 124. In attracting its outer-right armature, it operates relay H- H and slow rel ay 'H. The circuit for relay H H leads over conductor 176 and the outer right armature of relay B and conductor 189. Relay H then locks itself over conductors 174, 176, outer right armature and back contact of relay B, conductor 189, to battery atits resistance 187 in the calling line circuit. Re-

own armature and front contact. Relay H lay RT is thus connected to the ring side 165 of the calling line.

Relay RT ,is marginal and will not operate over the line circuit due to the high resistance 118 and relay L.- Resistance 118 is normally short circuited, its short circuit being removed when relay N N operates to ilp ls rease the margin of operation of relay The circuit remains in this condition until 11 being connected to conductor 189 is also held up by the armature of relay H. Relay H H in attracting its inner-right armature, connects grounded conductor 148 over conductor 147 to the release conductor 125, leading back to the primary line switch to maintain the cut-ofi winding 103 thereof energized independently of the ground suppllie'd at the inner left armature of relay. N

which relay. releases when -slo w relay conductor 148 is however extended to the sleeve conductor 125 by relay H H before relay N, which is slow, releases.

The calling party now operates his sender in accordance with the first digit of the wanted number, and on the return of the sender to its normal position, the following circuit including the impulse relay R is interrupted: free pole of battery, relay R conductor 126, inner left armature and front contact of relay S, conductors 127, 128, inner right armature and back contact of re lay B, lower contacts of relay A, the ring side 165 of the line, the substation loop, the tip side 164 of the line, the upper back contacts of relay A, left armature and back .contact of relay B, retardation coil 188 to ground at the middle left armature of relay S. The ground connected to the tip side of the line at springs 120 does not inter- Upon initial operation of relay R before the sender was operated, it closed atits lower front contact a circuit for'slow-to-operate relay D which in operating extended the front contact of relay 'R' to energize relay D D which connected the incoming and outgoing ends of the tip and ring conductors together, these conductors including a pair of condensers 129, 130. Upon the first retraction of the armature of impulse relay R, due to the sender interrupting the line,.relay D D instantly retracts its armatures, disconnecting the incoming tip and ring conductors from the outgoing tip and ring conductors. Relay D is constructed and arranged so that it will not again attract itsarmature while the impulse relay armature is vibrate ing. Relay D D thus remains inert during this period'to maintain the condensers disclcytnected from the outgoing ends of the t'p and ring conductors to prevent interference with the character of the impulsespby the discharge of the condensers.

Only parts of the switches S and C are shown, since these switches are well known.

' pulse relay 210 (Fig. 2) of the connector G is operated over the following circuit: free pole of battery, right winding of relay 210,

normal contact of relay 211. conductor 233,

ring conductor 212, multiple terminal 213 and brush 214 of the. selector S, ring conductor 215, secondary line switch contact 216, ring conductor 232, conductor 132, (Fig. 1) contact 133 of relay J, conductor 134, upper armature and front contact of relay R, conductor 135, conductor 136, contact 137 of relay D D, conductor 138, po larized relay P, tip conductor 139, contact 140 of relay J, conductor 194, tip conductor 225, contact 226, tip conductor 227, brush 228, terminal 229 of selector S, tip conductor 230, conductor 231, outer-normal contact of relay 211, left winding of relay 210 to ground. Relay 210 at its front contact operates slow relay 240, which interp oses a break in the circuit of release magnet 241 and grounds the sleeve Wire 245 in the wellknown manner. a The operations of setting the connector need not be described since they are well known and form no part of this invention. The impulse relay 'R, which isin circuit with the sender, at its upper armature and front contact controls thecircuit of the connector impulse relay 210.

When the connection has been built up to P the called line, the response of the called party operates relay 211 which reverses the flow of current in the tip and ring conductors leading back to the coin-collect circuit. Relay P, which is polarized, thereupon operates, closing a-circuit for relay 0 to prepare a circuit including the coin collect source C C and'the calling line. The circuit for relay C is as follows: free pole of battery, relay C and its normal upper con tact, conductor l42, armature and contact of relay P, conductors 192, 157,146 to the release conductor 125, which is grounded at the inner right armature of relay H H. Relay C in attracting its armature 155 looks itself to conductor 146. Relay J is'also energized over the following circuit due to the operation of relay P: free pole of battery, resistance 184, relay J, conductor 150, armature of relay K, conductor 142-, contact and armatureof relay P, conductors 192,- 157, 146, to ground over the path traced for relay C. Relay J locks itself over its armature 152, conductors 151, 157, to grounded con- ,ductor 146, as previously traced. Relay J reverses the connection of the tip and ring conductors 194 and 132 with the-tip and ring conductors 139, 134 for a purpose which will appear later. Relay C'in operating, closes the following circuit for relay A: free pole. of battery, relay A, conductor 154, uppermost armature and front contact of relay C, to the grounded sleeve conductor 124. Relay A extendsthe tip. and ring conductors leading from the primary line switch to the tip and ring conductors 1'39, 134, cutting off the bridge containing the impulse relay R and retardation coil 188. Relay R in releasing its upper armature removes the bridge containing the impedance coil 181 from across the talking conductors.

The subscribers may now converse. Talk ing current is fed from the connector to the calling line over the following circuit: free pole of battery, right winding of relay 210, outer armature and front contact of relay 211, conductors 231, 230, terminal 229, brush 228, conductor 227 contact 226, conductor 225, contact 159 of relay J, conductors134, 160, 161,'lower armature and front contact of relay A, contact springso162, 163, conductor 165 through the substation talk-set, conductor 164, spring 166, 167, conductor 164, upper armature and front contact of relay A, conductor 168, relay P, conductors 139, ,170, armature 169 and front contact of relay, J, conductor 132, conductor 232, contact 216, conductor 215, brush 214, terminal '213,

conductors 212, 233, inner armature and front contact of relay 211, left winding of relay 210 to ground. Current is fed to the called line over the windings of relay 211.

When the calling party replaces his receiver, ground is removed from the sleeve conductor 245 by therelease of slow relay 240, which causes the connector and selec tors-to restore. The removal of this round also releases relay S, which in releasing its outero left armature releases the secondary line switch SLS. Relay S at its outer right armature and back contact also closes afcircuit for relay Y as follows: free pole of battery, outer rightarmature and back contact of relay S, conductor 171, relay Y, contact 1172 of said relay, conductor 173, inner left armature of relay H'H, lower contact of the constantly operating interrupting machine I to ground, when the lower-contact is closed by the cam of the machine. Relay Y in operating, locks itself to grounded conductor 7 148 by closing its contact 177.

I front contact of relay Y. This relay Then the interrupting machine I next closes its upper contact, an impulse of current is delivered to coin current applyingrelay B over the inner left armature .and inv attracting its armature impresses positive curthe sleeve, conductor at the connector.

rent of preferably 110 volts from the collect source C C to the calling line to operate the polarized magnet PR in the coin box at the calling station to collect the coin. This circuit is as follows: free pole of source QC, conductor 178, lower armature and front contact of relay C, relay 190, conductor 179, left armature and front contact of relay B, upper armature and back contact of relay A, springs I67, 166, tip conductor 164, contact 120, polarized magnet PR to ground.- Relay A released when ground was removed frolrln T e polarized magnet PR operates to *collect the coin as shown and described in said Forsberg patent. In operating magnet PR locks Due to the closure of contact 119 the magnet 7 .PR remains operated as long as the coin current is ap lied, as shown and describedindetail'in sai Forsberg patent. In case the first s impulse from the interrupting machine fails to cause the collection of the coin, additional impulses are sent and the release of the primary line switch PLS is held up in the following manner:

When the relay B operated, in attracting its outer armature it opened the locking circuit previously traced for slow relay H, but

before the relay H can de energize, a substitute circuit is closed by the armature of relay 190 which operates in the coin current circuit in series with the polarized. magnet PR. Relay H as pointed out holds up relay, H H .which at its inner right armature is maintaining ground on thesleeve conductor leading to the holding winding 103 of the primary line switch. Thus these two alternate circuits maintain relay H operated until the ground at the substation is removed. As long as relay. Y remains operated, lamp 180 lights before an attendant,- who will investigate in case the apparatus does, notfunction properly.

Assuming, as in the normal case, that the polarized magnet PR functions properly, the second time the relay B operates from the interrupter I no groundwill be present at the substation andthe relay 190 will fail to operate and the substitute circuit for relay H at the front contact of relay 190,will not be present when relay B opens the other circuit at its outer right armature and back contact when it is next operated from the, interrupter I. Relay H accordingly releases, releasing relay H H. Relay H H in 1 0 retracting its. inner right armature removes ground from the sleeve conductor leading to the holding'winding 103 to the line switch, resulting in the release of the same. In case the called party has not respond- 105 ed, polarized relay P would not have shiftedits armature and relay C would have remained inert. At its lower armature, this relay wouldhave connected negative current from the volt coin return source OR to 110 the calling line to cause the polarized magnet PR to refund the coin, lock uptoground at contact 196, and open contact 120. 1 When the operating current ceases, magnet PR releases, opening contact 196 whereupon the primary line switch would release as described. 4

Certain lines called free lines are segregated'upon connectors which do not reverse the current flow in the calling line when the" 126 called party responds. On such calls, battery is fed to the calling line over the impulse circuit previously traced, the'relay being balanced by the retardation coil 188, the condensers 129, 130cseparating the calling. and called ends of the circuit.

The retardation coil 181 is provided in these calls to prevent short-circuiting the voice currents. Y

Upon disconnection in this class of calls,

, is refunded as in the case of unsuccessful calls.

Resistance 182 is connected to ground at one end and to the condensers 129, 130 at the other end over normal contacts of relay DD. The other terminals of these condensers are connected overnormal contacts of relay A to the armatures of relay 13 over which the relatively high potential coin current flows. This arrangement is for preventing the burning of the contacts of relay B when the? high voltage coin current is cut oil by the interrupter 1 releasing relay B.

The ground applied by the polarized magnet PR is connected to the tip side 164 of the line and the ground through the relay 210 at the connector is also normally applied to the same side of the line. However, when the relay 211 is operated when the called party answers, battery is connected to the tip side of the line and to prevent this change from affecting the release operation, relay J which operates due to relay 211 operating is pro vided to restore the original connections.

More particularly, when the calling party is the first to replace the receiver, inasmuch as relay J is locked .to ground on the release conductor 125, the holding circuit for relay 210 through its right winding to the coin ground, will be opened at the switchhook contacts 100 of the calling substation. Relay 210 therefore releases, opening the circuit of the usual slow relay 240. The re lease ofthe slow relay energizes the release magnet 241 which releases the connector and the release of the slow relay removes ground from the sleeve conductor 235, which releases the selectors. The selectors r'elease before the coin' collecting operations are completed and inasmuch as the ground on the release wire 125, to which relay J is locked, cannot be removed until these operations are completed the circuit referred to from the ground in the coin box to. the right winding of relay 210 is not ,closed.

When the called party restores first, relay 211 releases and reverses the current flow in the calling line. In this event relays J and K cooperate to prevent this condition from aflecting'release. When the relay J operated upon the response of the called party, it caused relay P to restore and closed a circuit for relay K by attracting its armature 183 this circuit including the grounded sleeve wire 125. Relay K at its right armature in operating prepares a circuit to shunt relay J. When the called'party replaces hisreceiver and reverses the current flow in the calling line, relay P operates and shunts out relay J over resistance 184, conductor 185, armature and front contact of relay K, contact of relay P, conductors 192, 157, 146, 147, inner right armature of relay H =H to grounded conductor 148. Relay P releases before relay K closes its back contact, thus preventing relay J from again operating. Relay J restores the original connections to the tip and ring conductors so that the ground in the coin box is now connected to the tip side 164 of the line to which the grounded side of relay 210 is connected.

Thus when the calling party restores his receiver, no circuit could be maintained closed from the 00111 ground to the wlndlng of relay 21-0 to which the free pole of battery is connected. Thus release is not prevented.

Relay P is located in the tip side of the line rather than the ring side so that if the.

called party hangs up immediately after the calling party and releases relay 211 thusreversing battery to the calling party befpre the slow relay in the connector has time to release and remove the ground from the sleeve wire which is holding up relay S, relay P will be operated when relay 211 releases over a circuit from the free pole of battery through right winding of relay 210 to the coin ground, thus shortcircuiting relay 'J as described, which reconnects the coin ground to the grounded side of relay i210 and, reconnects the side of relay 210 connected to the free pole of battery to the ring side of the line which is open at the switchhook. Thus release is not interfered with.

Certain levels of the selector S or a preceding selector may contain trunks leading to operators positions, such as information or toll operators. The induction coil 186 is provided to give such operators a tone to inform them of the character of the line. As shown in British patent No. 15138 of 1911, tone .may be induced in the secondary 197 of the operated by the removal of the receiver at the substation associated with'an yone of the calling'lines for causing said non-numerical switches to operate and extend the particular calling. line to an idle connecting circuit, a

coin collector at the callingsubstatio'n'having a magnet to collect or refund a deposited coin, means operated by the deposit of a coin in said collector for bringing about a circuit change in the substation equipment, a test relay in the connecting circuit at the central oflice operated in response to such circuit change, a controlv circuit. for said automatic: switches, a contact therein, an impulse relay for closing said contact operated over the calling line bythe energization of said test relay, and a sender at the I calling substation for operating said impulsechange system, the combination of calling relay to control the setting of said numerical switches. l p,

I 2. In a machine switching telephone exand called telephone lines, connecting circuits including numerical and non-numerical automatic switches, means automatically operated by the removal of the receiver at the substation associated with any one of the calling lines for causing said non-numerical said numerical switches.

switches to operate and extend theparticular calling line to an idle connecting circuit, a coin collector at the calling substation having a coin disposal magnet, means operated by the deposit of a coin in said collector for connecting said magnet to ground from one side of the line, a test relay in the connect ing circuit at the central oflice operated in response to such grounding of the line, a control circuit for said automatic switches, a contact therein, an impulse relay for closing said contact operated over the calling line by the energization of said test relay, and a sender at the calling substation for operating said impulse relay to control the setting of 3. In amachine switching telephone exchange system, the combination of calling and called telephone lines, connecting circuits including numerical'and non-numeri- ,cal automatic switches, means automatically operated by the removal of the receiver atthe substation associated with any one of the calling linesjor causing said non-numerical'switches to operate and extendthe particular calling lineto an idle connecting circuit, acoin collector at the calling substationhaving a polarized magnet, a relay L at the central office operated over i thecalling line circuit, a relay N N operated by said relay, a test relay connected tothe calling line bv said relay N N, a switch in said coin, collector operated by the deposit of a coin for connecting said test relay .to

ground from one side of the line, an imulse relay connected to the calling line loop y said test relay, an impulse circuit for said' numerical switches including a contact closed by said impulse relay, and a relay operated by said test relay for shunting said relay L.

' 4.- In a machine switching telephonelex? change system, the combination of a calling and a called line, connecting circuits including numerical and non-numerical automatic switches, means automatically operated by the removal of the receiver at .the substation associated w'th the calling line for causing said non-nu erical switches to operate and extend the calling line to an idle connecting circuit, a coin collector at the ;calling substationhaving a magnet for disposing of the deposited coin, means operated by the deposit of the coin for connecting said magnet to ground from one sideof the line, a. I supervisory relay 211 in the final numerical switch circuit operated upon the response of the called party for reversing; the calling line battery connections, thereby connecting the grounded side of said line to the same talking conductor of the final numerical switch as that to which the free pole of the battery is connected, a polarized relay P in series with the calling linefoperated upon this current reversal, and a second'currentreversing relay J operated bythe polarized relay to again reverse the current flowin the calling line, thereby. reconnecting the grounded side of said line to the talking conductor to which the grounded pole of the batttery is connected in the final numeri;

cal switch circuit.

5. In a machine switching telephone exchange system, the combination of a calling and a called line, connecting circuits including numerical and non-numerical automatic switches, means automatically operated by the removal of the receiver at the substation associated with the calling line for causing said non-numerical switches to operate and extend the calling line to an idle connecting circuit, a coin collector at the calling substatlon having a polarized magnet, means operated by the deposit of a ,coin for connecting said magnet from one side of the line to ground, a reversing relay in the final numerical switch circuit operated upon the response of the called party, thereby connecting the grounded side of said line to the same talking conductorof the final numerical switch as that to which theifree pole of the battery is connected, a calling supervicircuit which is connected to ground in the final numerical switch circuit, a release circuit for said switches controlledby the calling supervisory relay 210 in the final numericalswitch circuit, and means forholding said second reversing relay J operated until the switches release.

6. In a machine switching telephone exchange system, the combination of calling and called telephone lines, connecting circuits including numerical and non-numerical automaticswitches, means automatically operated by therenioval of the receiver at the substation associated with any calling line for :causing said non-numerical switches to operate and extend the particular calling line to an idle connecting circuit, a bridge line circuit for closing said prepared circuit to operate said polarized magnet to collect the coin, said bridge disconnecting means not being operated when the final numerical switch selects free lines, a source of talking current connected to the calling line over said bridge, and means operated by the restoration of the calling partys receiver for connecting the other source to the calling line to operate said polarized magnet to refund the coin.

In a machine switching telephone exchange system, the combination of calling and called telephone lines, connecting circuits including numerical switches, a coin collector at the substation associated with any one of the calling lines having a magnet to collect or refund a deposited coin, means operated by the deposit ofa coin in said collector for bringing. about a circuit change in the substation equipment, a test relay in the connecting circuit at the central oflice operated in response to such circuit change, a stepping circuit including a contact of said relay and the impulse relay of the first numerical switch, a sender at the calling substation forintermlttent-ly operating said impulse relay to control the setting of said switch and the succeeding switches to build up a connection to a called line, and means opcratedsubsequent to the response of the called party for impressing current on the calling line to cause said magnet to collect thedeposited coin.

8. In a machine switching telephone exchange system, the combination of calling and called telephone lines, a train of connecting circuits including numerical and non-numerical automatic switches, means automatically operated by the removal of the receiver at the substation associated with any one of the calling lines for causing the nonnumerical switches to operate and extend the calling line to an idle numerical switch circuit, a coin collector at the calling substation having a magnet to collect or refund a deposited coin, means operated by the deposit of a coin in said collector for bringing about a'circuit change 'in' the substation equipment, a test relay in one of the connecting circuits in the train of connecting circuits at the central office operated in re Sponse to such circuit, change, a control circuit for said automatic switches, a contact therein, an impulse relay controlled by the operation of said test relay for closing said contact, a sender at the calling substation for operating said impulse relay to control the setting of said switches, sources of current of difl'erent character at the central office, and means operative upon the breaking down of the connection and dependent upon whether or not the called subscriber has responded for impressing current I from the proper source to operate said magnet to dispose of the coin. I K I,

9. In a telephone system, telephone lines, a connecting circuit including a line switch and a first selector, means operated by the removal of thereceiver of the calling station for operating said line switch to extend the calling line to said first selector, a circuit including amarginal relay. said line and a high resistance, a coin collector at said calling station having a magnet, means operated by the deposit of a coin in said coin collector Jfor connecting said magnet to ground to shunt said high resistance to operate said marginal relay, an impulse circuit for setting saidselector. a dial at the substation, means controlled by said marginal relay in operating for placing said impulse circuitunder control of said dial, and means for impressing current on the calling line to operate said coin collector magnet to dispose of the deposited coin. a Q A 10. In a telephone system, telephone lines, a connecting circuit including a line switch and a first selector, means operated by the removal of the receiver of the calling station for operating said line switchto extend the calling line to said first selector, a circuit including a marginal relay at the central office, said line and a high resistance, a coin collector at said calling station having a magnet, means operated by thedeposit of a coin in said coin collector for connecting said magnet to ground to shunt said high resistance to operate said marginal'relay, an impulse relay, an impulse circuit for setting said selector: controlled by. said impulse relay, a dial at the substation, means controlled by said marginal relay in operating for connecting said impulse relay to the calling line in circuitwith said dial and for removing said marginal relay from connection with the calling line, and meansfor impressing current on said calling line to operate saidmagnet to collect or refund the deposited coin.

11. In a telephone system, a calling telephone line, a sender and a coin collector at the sub-station thereof, a central ofiice in .wliich said line terminates, an automatic numerical switch thereat, an impulse circuit for controlling the same, a clrcult lncluding an electromagnetic responsive device upon the initiation of a call, means actuated 1 posited coin.

at' the central ofiice and said line closed by the deposit of a coin in said coin collector for altering the electrical condition of said latter circuit, said device being responsive to said change to place said impulse circuit under the control of said substation sender, and means for subsequently impressing current on said calling line to operate said coin collector to dispose of the 'de- 12. In a telephone system, a calling telephone line, a sender and .a call charging means atthe substation thereof, a central ofiice in which said line terminates, automatic numerical switches thereat, an impulse circuit for controlling the same, a

circuit including an electromagnetic responsive device at the central otfice and said line closed upon .the initiation of acall, means operated by the actuation of said call charging means for changing theelectrical condition of said-latter circuit, said device being responsive to said change to place said impulse circuit under the control of said substation sender, and means for .subse uently impressing current on said calling line to operate said call charging means.

, 13. In a telephone system, a calling tele phone line, a sender and a coin'box at the substation thereof, a central oifice in which said line terminates, an automatic nu merical switch thereat, an impulse circuit for controlhng the same, means actuated by the initiation of a call for automatically extending the calling line to said switch,

,means operated by the deposit of a chin in said coin box to .ground one side of the calling line, a test relay at the central oflice operated in response tothe grounding of said line for placing said impulse circuit under the control of the substation sender,

coin box to dispose of the deposited coin.

14.. In a telephone system, a calling line, a sender and .call charging mechanism at the substation thereof, a central oflice' in which said line terminates, an autdmatic numerical switch thereat, an impulse circuit for settingsaid switch, means actuated by the initiation of a call for extending the of said charging mechanism for alteringthe circuit of the substation, a control circuit cuit under the control of the substation sender, and means for subsequently impress? ing current on said calling lineto operate said call charging mechanism.

15. In a telephone system, a calling line, a sender.) and a coin collector at the substation thereof, a central ofiice in which said calling line terminates, automaticswitches at said central oflice, a circuit for actuating said circuit actuated by the deposit of a coin,

said test relay being responsive to said a1 tered condition to place said impulse circuit under the control of said substation sender,

and means for subsequently impressing current on said calling line to operate said coin collector to dispose of the deposited coin.

16. In a telephonesystem, a calling line,-

a dial and a coin box at the substation there'-\ of, a central oflice in which said calling line terminates, a series of numerical switches thereat, an impulse circuit therefor, a line switch adapted upon the initiation of a call to extend the calling line to the first of said numerical switches, means operated by the deposit of a coin in the coin box for grounding one side of the line, a test relay at the central office'responsive thereto forplacing said impulse circuit under the control of the substation dial, and means for automatically selectively disposing of the deposited coin upon the breaking down of the connection. a

v 17. In a machine switching telephone exchange system, the combination of calling and called telephone lines, connecting'circuits merical automatic switches, means automatically operated by the removal of the receivers at the calling stations for causing said non-numericalswitches to operate and extendcalling linesto idle connecting circuits, call chargin mechanism at the call-' ing substations, sen ers at the calling suband marginal. electromagnetic stations, means at the central ofiice under the control of said call charging mechanism for render-iing saidnumerical switches respons ve to said senders.

including numerical and non-nu- 18. In a machine switching telephone exchange system, the combination of calling and called telephone lines, automatic switching mechanism for interconnecting said lines, call charging mechanism at the calling substation, means controlled by an operation for said switching mechanism, marginal means artthe central ofiice operated in response to such circuit change to govern said control circuit, and a sender at, the calling my name this 7th day of August A111, 1920.

ROY DOUGLAS CONWAY.

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