US1611692A - Machine-switching telephone-exchange system - Google Patents

Description

Dec. 21 1926. 1,611,692

R. L. STOKELY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM File p 1920 10 Sheets-Sheet 1 Busy fest Dec. 21 1926.

R. L; STOKELY- MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Sept. 25, 1920 10 s t 1-, 5

/n van/0r:

v d k m 5 L 1 V a Dec. 21 1926. 1,611,692

R. L. STOKELY MACHINE SWITCHINGl TELEPHONE EXCHANGE SYSTEM Filed Sept. 25. 1920- 1Q sheets-Sheet G //4v V6/4/0l: Hay A. Sfake/y Dec. 21,1926. 1,611,692

R. L. STQKELY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM 7 Filed Sept. 25. 1920 1Q s t s t 7 CHE Om /n van for: Ray L. SMA e/y Dec. 21 1926. 3 1,611,692

, R. STOKELY MACHINE SWITCHiNG TELEPHONE EXCHANGE SYSTEM Filed Sept. 25.1920 10 s s she 't 8 #5 "S W a H 2% o o s Q o 0 Q Q ls k &

Q N m K M Q E K) S s K) Q Q hvwn/or:

- Ray 4. SI ka/y.

Dec. 21 1926.

' R. L. STOKELY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Sept. 25. 1920 1Q h sy h g 9 Aw Q Dec. 21 1926. -1,611,692

R.' L; STOKELY MACHINE SWITCHING TELEPHONE EXCHANGE SYSTEM Filed Sept 1920 10 Sheets-Sheet l0 Patented Dec. 21 1925.

UNITE STATES RAY L. STOKELY, OF FLORAL PARK, NEW "SIC-BK, ASSIGNOB TO W'ESTER-N ELECTREG'CO,

, 1,611,692 PATENT OFFICE.

INCORPORATED, 61 NEW YORK, Y., ACOEFGRATIONOF NEVT YORK.

MACHINE-SVII'ICHING TELEPI-IGNE-EXGHANGE SYSTEM;

Application filed September 25, 18-20. Serial No. 412,795.

This invention relates to telephone exchange systems employing machine switch iug equipment and its object to provide an improved circuit arrangement to take care of toll calls in such systems, some or all of the substations whereof are equipped with coin boxes.

In accordance with one feature of the invention the toll ope 'ator after having built up a connection to the substation selects the connecting circuit used by means of an automatic switch. This switch is accessible to the .toll operator over two paths, the path chosen determining the character ofoperating current to be applied to the line to actuate the coin disposal magnet in the coin box, which current is automatically applied as soon as the connecting circuit is selected. More specifically, a circuit leading to an automatic switch is equipped with two jacks, one having a source of positive current associated therewith for connection to said circuit and the other a source of negative current. After the operator has built up the toll connection, she inserts the plug in the positive or collect jack, and by means-of her dial sets the automatic switch to select the connecting circuit over which she has built up the connection. A circuit change thereupon takes place to connect the collect cur rent to such circuit and thence to the selected telephone line to operate the magnet in the coin box to collect the coins deposited by the subscriber. If the coins are to be refunded, the operator inserts the-plug into the refund jack and likewise sets the automatic switch on multiples of the used trunk. Upon the completion of the selecting operation in this case, a circuit change takes place to connect the refund current to the connecting circuit and thence to the line to operate the coin box magnet to refund the coins. I

Preferably, the selection of the proper current is controlled by a double wound relay which normally prepares a circuit from the refund source to the brushes of the.

operators automatic switch, but when the plug is inserted in the collect jack an energizing circuit for the relay is closed to shift the connections to the collect source.

Referring to the drawings, Fig. 1 shows a toll cord circuit, Fig. 2 shows a trunk circuit outgoing from the toll board to a full me chanical o'l'l'ice, Fig. 3 shows a selector cir cuit, Fig. 3 shows a fragn'ientary modificaig. 3, Fig. 4 shows the relay and repeating coil equipment associated withthc toll transmission select-or circuit, Fig. 5 shows the toll transmission selector circuit, Fig. 6 shows a combination toll and local connector circuit, Fig. 7 shows the combination toll and local connector circuit for party line working, Fig. 8 shows a connector circuit for P. B. X. working, Fig. 9, shows a so-calledtoll terminal loop connector circuit, Fig. 10, shows the trunk circuit with connector for coin collect or refund, F 11 is a diagram of the manner :in which the drawings should be placed together in order to read the circuit.

Referring first to Fig. 1, this drawing shows a cord circuit at the toll operators position. The left hand side of this circuit will be called the toll end and the right hand will be called the toll and trunk end. The operator answers an incoming call by insert ing the plug T of the toll end in the an swering jack J in the ordinary manner. If the called subscriber is located in a nearby exchange, the call is completed by inserting the plug T1 of the trunk and toll end in a toll switching trunk jack TSJ. Theoperator then actuates the dialing and monitoring key DK which causes the relay -B34 to operate, which in operating energizes a monitoring relay not shown) to place the operators telephone set in a monitoring po sition on the cord. The operator now turns the dial 1) for the first digit of the wanted number. The dial in moving out of its normal position short circuits the relay E e-l4: permitting the relay E--72 to operate.' Relay E72 in operating locks itself to bat tery and transfers the tip of the plug TT through the impulse springs of the dial to the battery. The dial, inreturningto nor-' mal, interrupts the battery connected to the tip of the plug causing the impulse relay of the trunk circuit of Fig.2 to operate intermittently, the number of times depending upon the digit involved. This impulse re-, lay, in thus operating, causes the setting of the selector circuit of Fig. 3, which thereupon. automatically picks out an idle trunk in the selected level. lVhen the operator has operated the dial for all the digits involved which causes the last switch to be set on the desired line, she restores the monitoring DK. If the called. line is not busy, thetrunk and llt i toll supervisory lamp 100 l ghts, as a ringing sgnal. whereupon the operator by depressing ringing key RK causes the connector to start the ringing of the called line, which ringing continues until the called party answers, whereupon the lamp 100 is extinguished. \Vhen the called subscriber replaces his receiver, this lamp again lights.

lit the called line is busy or if one of the selectors had failed to find an idle trunk, the lamp 100 will flash, the frequency oi? the flashes depending upon the busy condition encountered. The toll operator in response to the flashing of the lamp removes the plug 'l 'l ot the trunk and tell end of the cord from the toll switching ack TSJ, but before removing the toll plug T the operator by means of her ringing key RK, rings on the toll line terminating at the jack J to notify the distant operator that the line is tree. 1f the distant operator rings first, however, the toll supervisory lamp 101 lights and is extinguished by operating listening key LK or 'pullingoutthe plug T. It the called subscriber is a distant one reached over a toll line, the toll operator inserts the plug TT of the trunk and toll end in the proper jack and by 111651118 0)? her ringing key RH. applies alternating current to the trunk to signal the distant operator. 1V hen the operator at the distant end applies ringing current to the trunk, the toll supervisory lamp 101 lights until the listening key Lli operated or the connection is taken down. The keys K and K serve, when operated, to disconnect either end of the cord from the operators telephoneset when the operator is talking on the other. When the plug '1 of the toll end is inserted in a toll answering jack, relay E-156 operates, in turn operating relay B162. Relay- 13-162 opens the circuit of relay E162 preventing the toll supervisory lamp 101 from lighting. When the plug TT of the trunk and toll end is inserted in toll switching trunk jack TSJ, relay F99 operates in series with relay 1 1- 155 and the lower winding of relay ll156. Belay l l-09 disconnects the busy test equipment of the operators telephone set from the tip of the cord and connects the tip of the cord through t0 the ringing key. Relay E155 is marginal and does not operate at this time on account of the high resistance in the sleeve of the trunk circuit; Ringing current applied by the distantoperatorover the toll line operates the relay A-190 which releases relay B162. The latter relay in'releasing lights the toll supervisory lamp 101 and operates relay E-162 in parallel with the lamp. Relay 1 1 162 locks up under the control of the listening key LK and relay 15-456 so that the lamp remains lighted after the ringing ceases and the relay 13-162 is'reoperated through the back contact of relay A 190.

relav E--162 operates and locks.

Thelamp 101 may be extinguished by operating the listening key 'hich releases relay E-l62 or by taking down the connection which releases relays l*l15t5 and F-1b2. Relay 13-162 is made slow in operating to guard against the possibility of lamp 101 being lighted by Morse impulses. Relay A19(5 may be operated for a short time by Morse impulses but will not remain operated long enough to cause the operation of relay lE-162. In case'relay l 1(32 should release momentarily, the slow operating feature of the relay 1') 102 will give the formertime to re-operate before the u W' hen both ends of the cord are inserted in the toll line jacks the marginal relay E 155 disconnects the relay B--1:-i from the cord circuit. When ringing current is received from either of the distant oiiices, relay A100 operates and lights the lamp 101. It, on a through toll connection of this character, the splitting key K is operated to disconnect the trunk and toll end from the operators telephone set, relay 15%; is bridged across the trunk and toll end so that it will operate when ringing current is received from the distant mike and flash the lamp .100. When the splitting key K is in its normal position the circuit for relay li ecg opened.

Referring now to Fig. 2 which represents a toll switching trunk over which a connection is extended to a nearby exchange, relay C-2 operates over its right hand winding when the operator inserts the plug 'i l into jack TSJ and by attracting its armature closes a loop circuit leading to the impulse relay A E Fig. 3, of the first selector. which in operating energizes slow relay B3 to prepare the impulse circuit. When the dialing key DK is thrown and the dial is operated, relay A2 operates connecting relay I2 across the loop leading to the impulse relay A3, Fig. 3. Relay l2 in operat ingcauses relay D-2 to operate, which relay shunts the left hand winding of relay C2 whereupon the latter relay releases, a circuit through its right hand winding being opened whenrelay E72, Fig. 1, operates as the dial is moved out of its normal position. Relay D2 in operating operates relay El which locks up to the ground at the inner left'cont-act of relay B 2, now energized. Relay E'2 at its outer lett contact holds up relay D2, independently oi, its ori "inal energizing circuit, at the front contact oi rclay 1 2. The dial in restoring intermittently operates relays A 2 and 1 2, relay l2 alternatelv opening and closing a shunt path arounu relay I)-2. If. during the operation of building up a connection. one of the selectors fails to tind an idle trunk in the selected group. it opens the loop circuit including relay I2. Relay I-2 in closing inn lli'i its back contact, shunts out relay D9.. Re-

lay l)--:l in closing its right hand back cou-.

tact operates relay lli Relay l-l-S locks up and connects interrupted battery of (it) impulses per minute to the windin of relay C-2 in shunt ot' the supervisory relay B- l3 in the cord circuit, Fig. 1. Relay follows these impulses and flashes the supervisory lamp 100 to indicate to the operator the failure to tind an idle trunk. In case the called line is idle. this condition causes the polarized relay FL to operate when the operator restores the key Dli which, in operating energizes relay G.3 which cuts the trunk through, thus disconnecting the relay C-2 and A2 from the circuit leading back to the toll operators position. In case the called line is busy, however, this polarized relay does not operate, the relays A2, I-2 and D-2 remain energized. the relay H2 is not operated and at its inner back contact connects interrupted battery of 120 impulses per minute to the winding of relay G-2 which causes the supervisory lamp 100 to flash to indicate to the operator the busy condition of the selected line. y r

Referring now to Fig. 10. When the op.- erator has built up the connection and found the line idle, applied ringing current, and the subscriber who originatedthe call and against whom the call was originally charged has responded, she requests the Slll)SClll')0l' to deposit the required coins in the coin box, which preferably of the type shown in Patent. No. 1,043,219 of Nov. 5, 19l2,'to O. F. Forsberg. The coins, in droppingin the coin box, strike bells which, in the well known manner, inform the operator of the character of the deposited coins. The operator then picks up a plug P and inserts it in a collect jack J10 at her position, and by means of the dial D1O and an automatic switch shown in Fig. 10, selects the trunk shown in Fig. 3 which is multipled to this automatic switch. If the plug is inserted into the collect jack a relay H10 oper' ates to prepare a circuit from a source of current of 110 volts positive polarity to the selected line to operate the polarized magnet in the coin box to collect the coins. It, on the other hand, the plug P-10 is inserted in the retund jack R1.0, relay H1O is not operated and consequently negative current of 110 volts is impressed upon the called line to operate the polarized magnet in the coin box iii-the opposite direction-to refund the coins. The upper armature ot' the relay ll- 10 in its attracted position closes a cir cuit tron! a tone source of one character to the operators head set which intorms her that positive impulses of current are being transmitted to the called line. This relay in its attracted position gives a different tone to the operators head set to indicate to her Consequently,

' Having described in a general manner the operation of the system, a call will now be v traced in detail.

The toll operator, having been informed of the number of'the wanted line and assun'iing this line to be in a. nearby exchange, tests for an idle trunk by touching the tip of her plug TI to the sleeve of the ack TSJ of the toll switching trunk in the Well known manner, and it she does not receive a click in her receiver she inserts the plug TT into the toll switching trunk jack TSJ. A circuit is thereupon closed to operate relays E-'99,,

(Fig. 1) and l3-2 (Fig. 2). RelayE-Qt). iuoperating disconnects the operators busy test circuit from the tip of the-cord. Relay l 2 (Fig. 2) in operating prepares certain circuits which willbe traced later. T his trunk will new test busy at the other operator's positions due to battery applied to the sleeve multiples by the sleeve of the plug T T. The insertion of the plug also closes the t'ollowing circuit to energize relay C 2: tree pole of battery, resistance 200, right hand winding of relay (3-2, conductor 201, armature 202 of relay G2, conductor 203, ring of the jack TSJ and plug TT, conduct-or 110, lower IlO111'1al CO11t21Ct of ringing key RK, rightliand winding of retardation coil 111, relay 'B-l-3, armature and back contact of relay which is not operated when the plug TT is inserted in the tol trunk switching jack, but only when it is inserted in a toll line leading to a distant otlice, left hand winding of retardation coil 111, upper normal contact of ringing key BK, armature andfront contact 'otrelay E99, conductor 102, right hand normal contact of relay E72, conductor'103, tip of the plug TT, tip of the ack TSJ, arinatin'e 204, back contact of relay G 2, and relay A-2 to ground. Relay A2 is marginal and does not operate in this circuit. Relay C 2 in attracting its armature closes the following circuit to operate relay A3, Fig. 3, which is the impulse relay ot the first selector, which is shown in Fig. 3: free pole of bat-' tery, lower winding 0t relay A.-3 (Fig. 3), conductor 300, back contact and armature 301 of relay D'3, conductor 302, conductor 205, conductor 206, outer left hand armature and back contact of relay ll2, conductor 20?, armature and front contact of relay C2, left hand winding of relay C-2, conductors 208 and 209, inner right armature and front contact of relay B2, conductor 210, polarized relay F 2, conductor 211, conductor 212, conductor 803, armature 304, back contact of relay D3, conductor 305, upper winding of relay A-3, conductor 306,

normally closed contact of switch 307, op-

erated on the eleventh rotary step of the selector, to ground. The operator now throws the dialing and monitoring key DK, whereupon a circuit is closed to operate relay B34l, Fig. 1, which in attracting its armatures causes the operator's head set to be connected across the cord. She now rotates the dial D for the first digit of the wanted number. The closure of the contact 104 of the dial as the dial moves off normal, shunts the relay B3 l which operates the relay E-72 and releases relay B34. Relay E72 in attracting its left hand armature locks itself to ground at the contact of the dialing key DK which when actuatedremains in its operated position until manually released by the operator. Relay I l-72 in closing its right hand contact con nects the free pole of battery through the impulse contact 108 of the dial to the tip of the plug interposing a break in the tip conductor. The interposition of this bneal: in the tip conductor opens the circuit heretofore traced through the right hand winding of relay C2. Marginal relay A-2 now operates in series with the impulse contact of the dial, the circuit being as follows: free pole of battery, resistance 109, impulse contact 108, right hand armature and front contact of relay E72, conductor 103, tip of the plug TT, tip of the jack TSJ, armature 20% and back contact of relay G2,

conductor 213 and relay A-2 to ground.

Relay A2 in attracting its left hand armature bridges relay 1-2 across the tip and ring of the cord in parallel with the left hand winding of relay C2. Relay I2 in attracting its armature closes a circuit, to operate relay D2 as follows: free pole of battery, resistance 214 conductor 215, relay D2, conductor 216, right armature and front contact of relay I-2 conductor 217, contact 218 of relay G-2 to ground. Relay D2 in attracting its left armature short circuits the left hand Winding of relay C2 which thereupon releases. thus opening one hand armature and front contact of relay A-2, conductor 211, conductor 212, conductor 303, armature 30a; and back contact of relay D3, conductor 305 upper winding of relay A3 and upper normal contacts 307 to ground. Relay D-2 at its right armature and front contact closes the following circuit to operate relay E 2: free pole of battery, relay E2 conductor 220, right armature and front contact of relay 1)2, conductor 221, conductors 222 and 228, inner left armature and front contact of relay l-2 to ground. Relay E2 in attracting its inner right armature locks itself to grounded conductor 222. The functions of this relay will be later described. Dial D, Fig. 1, in returning to normal, interrupts at its impulse contact 108 the circuit of the impulse relay A2, Fig. 2, which at its left armature interrupts the circuit of the impulse relay A3, Fig. 3, the number of times corre' sponding to the first digit of the wanted number. Upon each retraction of the armature of relay A3, the following circuit is closed for the vertical magnet 310 of the first selector: grounded armature 311, and back contact of relay D3, conductor 312, armature and back contact of relay A 3, lower armature and front contact of relay B3, slow relay C-3, vertical magnet 310, and free pole of battery. On the first step of the selector off normal springs 313 close the following circuit for relay 31 1-: free pole of battery, relay 314., conductor 315, off normal springs 313, conductors 316, 31?, armature and front contact of relay C3 to ground at the armature and front contact of relay B-3. Relay 314 in attracting its upper armature locks itself over the following circuit: free pole of battery, relay 314C, conductor 315, off normal contact 313, conductor 316, armature and back contact of rotary magnet 318, conductor 319, conductor 320, upper armature and front contact of relay 314i, conductor 321 to ground at the armature 311 and back contact of relay D3. Upon the cessation of the impulses, however, relay A3 remains energized and consequently relay C 3 which is slow to release, after an interval, releases whereupon the following circuit is closed to energize the rotary magnet 313 of the selector to step the selector brushes on to the first trunk in the selected level: free pole of. battery, magnet 318, conductor 322, lower armature and front contact of relay 314, upper normal contact of relay C3, upper armature and front contact of relay B3 to ground. At the end of its stroke, the rotary magnet 318 opens the locking circuit traced for relay 314. Relay 314; in retracting its lower armature opens the circuit of the rotary magnet. If the first trunk is busy, ground is present on the test multiple 323 thereof, whereby the following circuit is closed to energize relay 314:

hill

grounded multiple 823, test brush 324, conductor 325,- armature 326 and back contact of relay D3, conductors 327, 319, back con-- act and armature of magnet 318, conduct-or 2310, contact 313, conductor 315, relay 31 1 to free pole of battery. Relay 314. in attracting its upper armature again locks itself through the back contact oi" the rotary magnet and in attracting its lower armature again closes the circuit of the rotary magnetwhereupon the selector brushes are stepped to the next trunk. This action of the relay 314C and rotary magnet is continued until an idle trunk is found which is indicated by the absence of ground on the test multiple 323 thereof. When the rotary magnet at the end of its stroke positions the brushes on to an idle trunk and no ground is present, relay 314 does not energize but relay DS energizes over the following circuit: iree pole of battery, relay 31a, conductor 315, contact 313, conductor 316, armature and back contact of rotary magnet 318, conductor 319, conductor 327, conductor 328, relay 13-3, conductor 329, lower normal contact of switch 307, conductor 33 to ground at the upper armature and trout contact of relay B3. Relay 31 is marginal and does not operate in this circuit. Relay D3 in attracting its armatures 1 and 301 extends the talking conductors through to the selector brushes and cuts of? impulse relay A3.

Assuming now that the selector has failed to find an idle trunk. In that event on the eleventh rotary step, switch 30? operates and opens at its uppermost contacts, the circuit of the impulse relay .+'\3 which causes the selector (Fig. 3) to restore.

The opening of this loop circuit also causes relay l2 to be permanently deenergized. Relay A2 in remaining attracted and the relay I-2 being inert, the following short circuit is closed about the slow relay l) 2 to cause the same to release: free pole oi battery. resistance 214, right hand armature and front contact of relay A-2, armature and back contact of relay I-2, conductor 217. contact 218, to ground. It will he understood that relay D-2 is slow to release as shown and holds up between the impulses of one digit. Relay D-2 in re- 1ra- ;-ling its right armature operates relay I l-2 over the following circuit: free pole of battery. relay H2, conductor 222. armature and. back contact of relay D-2, conductor 220, inner right hand armature and trout contact of relay E-2 to ground on conductor 24-2. Relay I *2 in attracting its inner le'tt armature locks itself up to grounded conductor 242 and in attracting its inner right armature connects interrupter to the inner left hand armature and front contact oi? relay Fi2 to shunt the i'csisuance 200 to cause supervisory relay l3-43 in the cord circuittoflash the trunk ancltoll supervisory lamp 100 at the rate of flashes per minute when the operator restores the key DK. -This rate of flashing will indicate to'the operator that one of the switches has encountered a busy trunk group whereupon she will pull out the plug and will thenwait and set up the connection later, or insert the plug into another jack and again set up the connection by way of another trunk. lVhile the interrupting machine 223 is connected to the front contact of relay H2 as soon as relay D-2 releases, this operation is not effective to flash the lamp until the operator, after having turned the dial for the last time, releases her dialing key DK, Fig. 1. The opening of he lowermost contact of this key releases relay E72 which in retracting its right armature again closes the loop circuit including the right hand winding of relay 0-2, Fig. 2, and the relay A2 Fig. 2 and B-4E3 (Fig. 1). It will, of course, be understood it no idle trunk is found relay G2 is not energized.

The relay H2 in attracting its outer left armature interposes a break in the loop circuit leading'to the selector (Fig. 3) thus presenting the subsequent sets of impulses from operating the switches.

The seizure of the toll transmission selector, Fig. 5, with which the relay and repeating coileequipment of Fig. l is associated, causes the closure-0t the following circuit for impulse relay .A5, Fig. 5 of the toll transmission selector: tree pole of battery,

right hand winding of relay A5, conductor 500, conduct-or 4100, conductor 401, outer left armature --and back. contact of relay B-t, conductor 402. contact 403 of relay F4-, conductors 104, 4:05, upper left hand winding of repeating coil 406, conductor 407, multiple terminal 351, brush 350, conduct-or 352, armature 304 and front contact of relay D-8, conductors 303, 212, conductor 211, left armature and front contact of relay A2, relay I2, conductors 298, 207, outer let't hand armature and back contact ot relay I-l2, conductors 206, 205, 302, armature 301 andtront contact of relay D Z). conductor 332,.brush 3333, multiple terminal 334:, conductor 408, lower left hand winding of repeating coil400, conductor 409, contact 410 of relay F-4, conductor 411, contact 412 of relay B4, conductor 413, conductor 501, through the left winding of relay A-5 to ground. at the lower normal contact. of the switch 502. which is operated on the eleventh rotary step of the transmission selector. The impulse relay A5 in attracting its right armature energizes slow relay l" 5. This relay in attracting its left armature closes a circuit for relay which in attracting its armatures applies a local ground to the test multiple to cause this trunk to test busy. Relay 336 is provided when the til) transmission selector is not located in the same otlice as the selector circuit of Fig. 3, to take care of differences in ground potentials and trunk resistances. If the toll selector is in the'same office, ground from the outer left armature and front contact of relay B5 is transmitted to the test muliple 323,

called line causing relay A2 Fig. 2 to open and close the loop circuit for the relay A5, which in vibrating its right hand armature transmits impulses over the following circuit to the vertical magnet 508 of the toll transmission selector: right armature and back contact of relay A5, inner armature and front contact of relay B.5, conductor 509, armature 510 and back contact of relay D5, conductor 511, slow relay C--5, magnet 508. to free pole of bat-- tery. The brushes of the toll transinisslon selector are thus elevated to the desired level. When the dial returns to normal and maintains the relay A-2 energized, relay A.5 remains energized and, after a slight interval, slow relay C5 releases. When the relay -5 operated on the first impulse and the selector took its first step, relay E-5 corresponding to relay 314, Fig. 3, operated over the following circuit: free pole of battery, relay E-5 upper contact of off normal switch 515, conductor 516, armature and front contact of relay C-5, conductor 517, conductor 518, conductor 503 to ground at the right armature and front contact of relay 13-5. In attracting its inner armature, relay E5 locks itself to the upper armature and back contact of slow relay F5, this circuit including the armature and back contact of rotary magnet 519. These circuits are similar to those of the selector of Fig. 3. Upon the cessation of. the impulses and therelease of the slow relay C5, the circuit of the rotary magnet is closed as follows: free pole of battery, magnet 519, outer armature and front contact of relay E5, normal contact of relay (3-5, conductor 517, conductor 518, conductor 503, right armature and front contact of slow relay l3 5 to ground. The rotary magnet advances the brushes on to the terminals of the first trunk and at the end of its stroke opens the locking circuit of the relay E5 which releases opening the circuit of the rotary magnet. If the trunk is busy, relay E5 again energizes over the following circuit: free pole of battery, relay a-5, upper contact of switch 515, conductor516, conductor 520, armature and back contact of rotary magnet 519, conductor 521, conductor 522, back contact and armature 523 of relay D-5, conductor 524, lowermost armature and back contact of relay F5, conductor 525, test brush 526 to ground on the test multiple 527. Relay .F-5, in attracting its inner armature again locks up through the upper armature and back contact of relay F 5 and at the other armature again closes the circuit of the rotary magnet which advances the brushes to the next trunk and at the end of its stroke opens the locking circuit of relay E 5 which in retracting its armature opens the circuit of the rotary magnet 519. The switch 502 of the toll transmission selector, Fig. 5, corresponds to the switch 307 of the selector circuit, Fig. 3. Its function is to open the circuit of the impulse relay A-5 on the eleventh rotary step of the toll transmission selector, that is to say, if all the trunks in the group are busy. The opening of this circuit releases the switch and causes relay 1-'2, Fig. 2, to become permanently inert which causes the release of slow relay 2 and prepares a circuit for the interrupter 2 3 which results in the flashing of the trunk and toll supervisory lamp 100 when the operator restores her dialing key as described in detail in connection with Fig. 3. If, however, an idle trunk is found, relay D5, which corresponds to relay l)3, Fig. 3, ope ates over the following circuit: free pole of battery, relay E5, upper contact of switch 515, conductor 51G, conductor 520, armature and back contact of magnet 519, conductors 521, 522, relay D5, upper normal contact of switch 502, conductors 530, 503 to ground at the right armature and front contact of relay 502. Relay E5 is marginal and does not operate in this circuit in series with the relay D5. Relay D5 then operates and in attracting its armatures 531 and 532 extends the talking conductors through to the talking brushes 533 and 534. The attraction of the armature 523 of relay D5 grounds the test brush 525 and consequently test multiple-527 of the selected trunk, causing the same to test busy to other selectors. The contact 535 is made before the contact 500 is broken by the armature 537 of the relay D5. Consequently relay D4, Fig. 4. in the relay and repeating coil equipment is maintained energized over the following circuit: free pole of battery, relay D4 conductor 415, outer right armature and back contact of relay F-4, conductor 414, conductor contact 535, conductor 538,

cuit. Relay D& in retracting its outer right hand armature operates relay F 4, Fig. 4, over thefollowlng circult: free pole of battery, relay F4, conductor 428, outer right armature and back contact of relay D4, conductor 429, conductor 550, armature and front contact of relay D5, conductor 518 to ground at the right armature and front contact of relay B5. Relay F4 in attracting its outer right armature closes a substitute ground to hold up the relay F6 to prevent ringing from occurring at this time: ground right hand armature of relay El, conductor 430, right armature and back contact of relay l:$4, outer right armature and front contact of relay 1 -4, control conductors 4:14 and 501', contact 535 of relay D5, conductor 538, brush 539, multiple 540, conductor 541, conductor 600, front contact, armature 685 and lower winding of relay F6 to free pole of battery. Relay I -6 was energized upon the first impulse .to the vertical magnet, this circuit being as follows: free pole of battery, lower winding of relay F6, lower armature and front contact of slow relay 619, innermost righthand armature and front contact of relay J-6, conductor 614, conductors 631 and 615 to ground at the upper inner armature and front contact of relay B6. When energized, relay F-6 locks by Way of its armature 635 and front contact, conductor 601, armature 602 and back contact of relay K-6 to grounded sleevewire 650. Consequently, the operation of relay K-6 to cause the reversal of direction of the current flow in the loop leading back to the toll operators position would deenergize relay F-6, and unless a substitute circuit is provided for holding up relay F--6 the ringing operation would automatically take place. This is prevented by applying ground to the control conductor 600 over the circuit traced to hold the relay F -6 until the operator, by depressing a key as will be explained, releases relay F-6 to start the automatic ringingoperation. The release of the relay D1 and the consequent energization of relay F-4 as described reverses the direction of current flow in the talking conductors lead- 1ngback to the operators position. After having turned the dial for the last time, the operator restores her dialing key DK which releases relay E-72 which disconnects the dial from the tip of the plug-causing the release of the relay A-2, Fig. 2, and causes the closure of an energizing circuit for the right hand winding of relay -2, relay B-lS and relay A2. Relay A2 it will be remembered, releases under this condition and in retracting its left armature deenergizes relay I-2, which in releasing causes the release of relay D-2. The polarized relay F2 is now bridged across the following circuit: upper talking conductor 212, l ig. 2, conductor 211, polarized relay F-2, conductor 210, inner right armature and front contact of relay B2, conductor 209, conducior 208, left hand winding of relay 0-2, armature and front contact of relay C2, conductor 207, outer left armature and back contact of relay H2, conductor 206 to lower talking conductor 205. The reversal of the direction of current in these talking conductors due to the operation of relay F-4 causes the relay F2 to cooperate closing the following circuit for relay (Jr2:'free pole of battery, relay G2, conductor 22%, contact 225, of relay F2, conductors 226, 227, 228, inner left armature and front contact of relay 13-2 to ground. Relay G-2 locks itself up over the following circuit: free pole of battery, relay G2, conductor conductor 229, front contact and armature 230, of relay G-2, conductor 225i, conductor 227- to ground at the inner left hand armature of relay B2. Relay G2 connects the talking conductors of Fig. 2 through to the talking conductors of Fig. l whereupon. the trunk and toll relay Bl3 operates in series with the relay A5, Fig. 5, and lights the supervisory lamp 100 as a ringing signal to the toll operator. Relay G2, Fig. 2, cuts off the bridge including relays C-2 and A-2. The operator now operates her ringing key BK which impresses alternating current upon the talking conductors and operates the alternating current relay Cl which in attracting its armature operates the relay E-L This relay in attracting its right armature opens the cir- V cuit heretofore traced, which has been holding relay F6, Fig. 6, energized. This relay in retracting its armature 68? connects ringing current to the called line through the upper winding of relay F6. This ringing current is automatically continued until the called party removes his receiver, resulting in the increase in the current through the upper winding of relay F6 causing the same to operafe removing the ringing current. The attraction of the armature 635 of this relay closes a locking circuit for the same over control conductor 600. The extension of the tip and ring conductors by relay F-6 to the called line operates relay A4 over the winding of which talking current is fed to the called line. Relay A-% in operating energizes relay B% which in attracting its right hand armature applies ground to the conductor 41 1- to hold up relay F6, Fig. 6, independently of the relay El. Relay Bl in attracting its left hand armature opens the connection of battery through the windings of relay A5, Fig. 5, to the talking conductors 407, 408, leading back to the operator's position which causes the deenergization of supervisory relay B l3. This relay in retracting its armature extinguishes the supervisory lamp Ill) 100 which notifies the operator that the subscriber has responded. Talking current is fed to the called line over the winding o-f relay r -4 and the repeating coil 406. This talking circuit is a standard repeating coil transmission circuit used in long distance connections. Talking current is fed to the calling line from the calling distant exchange. During conversation the trunk leading from the lefthand windings of repeating coil 406 through the right hand winding of the repeating coil (not shown) at the distant oflice is dry, in accordance with standard practice. The operator may now request the subscriber at the substation shown in 6 to deposit the necessary coins in the coin box which may be of the type shown in said Patent 1,043,219. These coins in passing through the box strike gongs whereby the operator is informed of the denominations of the coins inserted. When she is satisfied that the proper coins have been deposited 'she picks up her plug P-10, Fig. 10, and after touching the tip of the plug to the tip of the jack and finding the same idle, she inserts it into the collect jack J-10. The insertion of the plug P-10 closes a circuit for relays E-91 and E-99 over the sleeves of the plug and jack, and relay E-9l thereupon operates the signals 1002, and 1003 at the positions in which the multiples of this jack appear. Relay 13-99 in operating disconnects the busy test circuit and connects the dial D-lO to the tip of the plug. Battery on the sleeve of the plug causes the multiples of the seized trunk to test busy at the other positions. The operator knowing the number of the trunk shown in Fig. 3 because of the designations on the jacks themselves or the designation strips associated with the iacks, now rotates her dial to set the automatic switch shown in Fig. 1.0 to connect with the multiples of the used trunk which appear in this switch. The automatic switch of Fig. 10 and all apparatus shown at the right of the dotted line is located at the distant automatic oiiice: that is to say in the same office with the selector of Fig. 3. The equipment shown at the left of the dotted line of Fig. 10 is located at the toll office. The insertion of the plug P-10 energizes the impulse relay 14-10 over the following circuit: free pole of battery, resistance 1050, impulse springs of the dial, armature and front contact of relay ll99, tip of the plug P-10, tip of the jack J 10, conductor 1005, conductor 1006, upper normally closed contact of ofl normal switch 1007, conductor 1008, impulse relay A-10, conductor 1009, conductor 1010, ring of the jack il-10, ring of the plug P-10 to ground. The impulse relay in opcrating energizes the usual slow to release relay B-10. Relay B-10 in attracting its outer right armature closes a circuit for the upper winding of relay H-lO. This winding of relay 1 1-10 when energized is not sufficiently strong to cause the relay to opcrate but is sufficient to cause relay H-10 to operate when the current through the lower winding is in the right direction to aid the current in the upper winding; lower winding of relay H-lO will not cause the operation of the relay H-lO, when the current flowing in the upper winding opposes that flowing in the lower winding. The lower winding however is shunted while the switch shaft is in its normal position.

-Upon the return movement of the dial the impulses are transmitted to the impulse relay A-lO. Upon each retraction of the armature of this relay an impulse is transmitted over the following circuit to the vertical magnet 1013 of the switch; ground, armatureand back contact of relay A-10, inner armature and front contact of relay 13-10, lower normally closed contact of aif normal switch 1007, slow relay C-lO, vertical magnet 1013 to free pole of battery. The first step of the switch operates the off normal switch 100? which removes the short circuit from around the lower winding of the relay iii-10, whereupon relay H-lO operates and shifts the armature 1012 from its normal connection with the refund source of 110 volts negative current to connection with the collect source of 110 volts positive cur rent.

Upon the first vertical step the 0H normal switch 100'? operates and the succeeding impulses then pass by way of contact 1015 and the armature and front contact of slow relay (3-10. Upon the cessation of the impulses the slow relay C-10 releases preparing a circuit for the rotary magnet 1016 closed upon the return of the dial for the units impulses. The impulses now pass from the back contact to the stepping relay A-10, inner armature and front contact of relay 3-10, contact 1015, armature and back of relay 6-10, slow relay E-10, outer right hand armature and back contact of relay D-10, rotary magnet 1016 to free pole of battery. Relay E-10 in attracting its outer left armature energizes relay D-10 which in attracting its left armature locks up to the outer right armature of relay 13-10. Relay E-10 in attracting its inner left armature operates relay F-lO. Relay 13-10 in attracting its right armature connects the rotary magnet in the stepping circuit independently of the outer right armature of the relay D-10. Now when the units impulses have all been transmitted the slow relay E-lO, after a slight interval, releases. The retraction of its inner left armature opens the circuit through the left winding of relay F-lO. If at this time the interrupter-1017 is on a metallic segment relay F-10 will be held up by its armature. lVhen the interrupter passes to the next insulating segment relay F'10 releases .and its armature connects relay G10 over the inner right armature and front contact of relay D10 to the interrupting 1na- :chine 1017. It will be apparent that the re- :lay F10 is provided to insure that the first impulse to relay G10 will be a full one.

The brushes 1018 and 1019, being now in contact with multiples 1020 and 1021 of the trunk shown in Fig. 3, upon the first engagement of the interrupting machine brushes with the metallic segment after relay Fl has released, an hnpulse is transmitted to the relay -G10 which, in attracting its armature connects the source of collect current by way of the brush 1018, multiple 1020, conductor 345, Fig. 3, uppermost armature and front contact of relay D3, Fig. 3, conductor 3'37, brush 338, multiple 339, conductor 482, relay G4l, resistance 434C to ground. Relay Gl connects relay K-d to the interrupter 1017 which is the same machine as that indicated by the same reference character in Fig. 10. Each time relay K4 operates, it extends the conductor 432 to the ring conductor 416 and tip conductor and thence to the called line, this circuit including switch hook springs of the substation telephone set, contact 638 in the coin box, polarized magnet P of the coin box to ground. Current will flow through relay J-10, Fig. 10, to ground at the coin box each time relay G'-1'0 operates until the coins have been collected in case they are not collected upon the first operation of the polarized magnet P. When the polarized magnet P operates and collects the coins the contact 638 in the coin box at the substation is opened consequently relay J1O no longer operates. Each time relay J1O operates tone is placed on the toll switching trunk to indicate to the operator that the proper current is being sent out to the called line. This circuit leads from a source 1022 over the front contact and armature 1023 of the relay H1-0, armature and front con tact of relay J"10, condenser 1-069, brush 1019, multiple 1021, Figs. 10 and 3, which multiple is connected to the tip conductor of the trunk from whence it is transmitted to the operators head set. The toll operator, ceasing to hear the tone impulses, knows that the coins have been collected and pulls out the plug P10. If the polarized inagnet fails to collect the coins or if the coin box fails to function properly for some reason or other the contact 688 remains closed and the repeated impulses of tone will inform the operator of this condition and she will pull out the plug and report the line. The removal of the plug causes the release of the impulse relay A-10 and slow relay E 10 which closes the following circuit for the release magnet J1025; free pole of battery, magnet J1025, upper contact of the off normal s itch 1007, inner armature and back contact. of slow relay B-10 armature and back contact of relay J lL-1O to ground. The release magnet restores the switch and the switch, upon reaching its 110111121] position, restores oil nruimal switch, 100?.

it the operator had plugged into the refund jaeh R10, if for any reason the coins were to be rot-untied, the cun'ent in the lower winding of relay 1-1-10 would oppose that following in the upper winding and relay H- would not operate when the oil normal switch 1-00? opened the shunt about the lower winding. Consequently the armatures of relay l-l10 would have remained retracted, the armature 1012 connecting the refund source of negative on rent to the called line to operate the iola-r-ized ma net b P in the opposite direction to refund the coins to the subscriber. Armature 1023 at its contact would connect a source of refund tone 1027 in circuit with the operators head set each time the relay J"-10 operated. As

in the case where the coins were collected, the toll operator ceasing to hear refund tone impulses knows that the coins have passed through the box and she removes the plug from the refund jack.

It is of course understood that the tone sources 1022 and 1027 are of different character for era nple, the refund source can he L pulsations per second and the collect source 150 pulsations per second.

Assuming now that the desir d line when selected by the connector is busy. In that condition the test multiple 626, Fig. 6, is grounded. lVhen test wiper 627 is set on the busy multiple 626, ground is extended over brush 62?, conductor 628, contact 6 10 of relay ill-6, conductor 6% armature 6 12 and back contact ot relay H-6, conductor 6&3, relay (i-(i to free pole of: battery. Relay G 6 energizes and when relay E-(i reler" s locks itself up over the following circui tree pole of battery, relay G6, conuuctor 6&3, armature 642 and back contact of relay 1-1- 6, conductor Gil, make hefore break contact of relay ll6 right arniature and front contact of relay G -6, eonductor 631, conductor 615 to ground at the armature (S16 and trout contact of relay l6. Relay (71-6 in the case of a local call connects busy tone "from the source 045 to the calling line. In the case a toll call this busy tone is not used, a this ing signal being Yen to the operator instead. reason of the ground ccnncctin to the mul: tiple 626 of the selected line i does not operate. (lonsequen't is not energized to open the c D Fig. as described the ca e of an line. nasinuch as 1' ll- .inains TI. lt ii" energized, relay F-d, whose circuit is main-

Images