US2372262A

US2372262A - Telephone station circuit

Info

Publication number: US2372262A
Application number: US421534A
Authority: US
Inventors: William H Edwards; Oscar A Shann
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1941-12-04
Filing date: 1941-12-04
Publication date: 1945-03-27
Anticipated expiration: 1962-03-27

Description

March Z7, 1 945. w, WA ETAL, 2,372,262

TELEPHONE STATION CIRCUIT 4 Sheets-Sheet 1 Filed Dec. 4, 1941 W H. E DWARDS O. A. SHANN INVENTOR$= ATTO NE) March 1945. w. H. EDWARDS ET AL 6 TELEPHONE STATION CIRCUIT FiledDec. 4, 1941 4 Sheets-Sheet 2 lab 84 M. H. EDWARDS WI/ENTORS 0. ,4. SHA/V/V.

BY $04,; J

ATTOR 5y March 27, 1945. w. H, EDwARfis ETAL 2,372,252

TELEPHONE STATION CIRCUIT Filed Dec. 4, 1941 4 Sheets-Sheet 3' .WH. EDWARDS jf 0.,4. SHA/V/V ATTO IVE) March 27, 1945.

W. H. EDWARDS ETAL TELEPHONE TSTATION CIRCUIT Filed Dec. 4, 1941 4Sheets-Sheet 4 FIG. 9

FIG. /0

n01 EDWARDS INVENTORS- a A. 5

B y HAN/V Patented Mar. 27, 1945 TELEPHONE STATION CIRCUIT William H. Edwards, Great Neck, N. Y., and Oscar A. Shaun, Short Hills, N. J., assignors to Bell Telephone Laboratories,

Incorporated, New

York, N. Y., a corporation of New York Application December 4, 1941 Serial No. 421,534

27 Claims.

The invention relates to telephone station circuits.

An object of the invention is to protect dial type telephone stations against unauthorized use.

Telephone station circuits including a calling dial or signaling or pulsing device, for inclusion in socalled automatic telephone systems, are becoming increasingly common. The telephone station may be intended for, and be sp located as to be available for, use by only one or by a relativelyfew persons, as in a private home or in an office. On the other hand, the telephone station may be intended for use by the general public, and may be mounted on a wall or in an enclosure, such as a booth in a public place.

In the former case, the subscriber or sub scribers, that is, the private individual or family or the office occupant, may Wish to restrict the use of the telephone to himself, and to protect it whenhe is not present against unauthorized use by others in the house or office who have Or who might contrive to have physical access to it. At

the same time, it will be desirable to have the station, while so protected, in a condition to receive incoming calls and/or to be available for emergency outgoing calls. In some cases where a key telephone set for a secretary is provided with facilities to pick up and answer one or more principal lines, it may be desired, if it could be done simply, to restrict the use of the line for outgoing calls to the principal station or stations, at the same time permitting the secretarial station to be used for outgoing or incoming calls on another a line or lines. It is desired also to accomplish this with the minimum additional equipment, wiring or cord conductors, or less thanwould be required if the dial contacts were short-circuited directly.

In accordance with one feature of the invention a key or look controlled impedance, specifically, a resistance, for example, having a negative resistance voltage characteristic, such as a silicon carbide varistor, is provided in the telephone station circuit. This impedance normally is opencircuited, but when it is desired to protect the circuit against unauthorized use, operation of the key or look connects it in shunt with the microphone or transmitter (and, when convenient from a wiring standpoint, with the induction coil primary winding also) and withthe pulsing springs or contacts of the calling dial of the circuit. The

' impedance is of selected value such that dial pulses are effectively short-circuited but the transmitters (and, when so connected, the induction coils) effectiveness for talking purposes is not affected appreciably. For example, when a varistor is employed, with the dial contacts open,

the varistor would have a comparatively high voltage across its terminals and its resistance would drop to a low level. However, with the dial contacts closed in the talking condition, the voltage across the varistor would be comparatively low and its resistance would be comparatively high.

In installations in which the station components .other than receiver, transmitter, calling dial and mounting therefonare located in an enclosure at a removed or relatively inaccessible location, the shunt impedance and the contacts to connect it may be housed in such enclosure. Since the transmitter is not affected appreciably. by the shunt, use. of the station in answering incoming calls is not impaired. The station may be used for emergency outgoing calls by removal of the receiver or handset (if the station is equipped with the latter) and waiting for the. sender monitor or the dial system A operator to.

come in on the line when dialing is not started after a reasonable period of time.

In installations in which all .of the station componentsare associated with a so-called combined telephone set, that is, one in which all of the station components are mounted onor enclosed in a single housing or mounting, the shunt impedance and'the contacts to connect it may be housed in the combined set. or the shunt impedance and the contacts to connect it may be housed separately so as to be mounted in a position less con spicuous or more remote from the position of the possible unauthorized user or the telephone, but accessible to the legitimate user. For example, a telephone set might be provided on a counter or in a cashiers booth in a store where anyone might use the telephone for incoming calls, but be unable to use it for outgoing dial calls until the shunt impedance circuit is opened. In a key telephone set, the shunt impedance could be mounted in the set and permanently connected in the wiring thereof in such a way that dialing out'is disabled on one or more lines and unaffected on other lines picked up by the same set. If desired, however, a control could be provided from some remote point which would determine what line could be used for outgoing calls from the key telephone set in question.

In pay station telephones or coin collectorstations that include. a calling dial and that require the deposit of a coin or token to initiate a call to another party or to get the operator, it is a known practice to provide normally'a shunt around the pulsing contactsor springs of the dial, the shunt being removed by the deposit of the coin or token. This insures that should the line circuit somehow be completed to the automatic exchange or central office without the deposit of a coin, the dial remains inoperative for pulsing purposes. When the coin collector station is of the handset type it is known,also,--to..include in-ithe station .a coin signal microphone-or transmitter for-the sole purposeof picking up the sound of a deposited coin or coins. and transmitting the sound or sounds to the operator in the case of a toll or other call requiring the operator to be signaled. "Toisimplify the station circuit, the coin signal microphone may be connected in series with the'dialpulsing contacts or springs. lector structure and circuit arrangement provision of the pulsing spring shunting arrangement involves shunting the'signal' microphone also. [As will be brought out in greater' detail hereinafter this is not entirely advantageous since; under certain circumstances, the coinsignal'microphone is not efiective for its'intended purpose.

In' accordance with another feature ofthe' invention, the shunting o'i-rcuitfor' thedial pulsing springs includes'an impedance, specifically *a' resistance; so' proportioned that. until theshunting circuit is opened or disconnected, operation'of the dial is ineffective to transmit pulses to the linebut the coin signal micro hone effectiveness for transmission of'coin. deposit sounds is not sub-. stantially' affected.

Still other objects and featurescomprehended in the present invention will. becomeiapparent from the detailed description that follows; taken in conjunction with the appended drawings. wherein:

Fig. 1 illustrates typical telephone station equipment in whi'chthe invention may beembodied. alternative. supporting structure T for the handset, or transmitter and receiver; and calling dial being shown;

Fig. 2 shows a circuitarrangement.embodying theinven-tio-n, which circuit. andwhosecomponents .are adapted to be includedin-the telephone station of Fig. 1;

Fig. 3 shows a modification of the circuit arrangement of Fig. 2. incorporating anti-sidetone;

-'Fig. 4 illustratesatypical paytelephone or coin collector station; v

Fig. 5-showsa circuit arrangement embodyingthis invention which circuit and-whose components are adapted to be included in the coinrcollector station of Fig.4;

Fig. 6 illustratesa subscriber's stationi installation including a 'main and an extension set eachequipped with a calling dial, one" of which may be. disabled for outgoing calls therefrom by inclusion in its circuit of the. shunt; impedancemeans of -this invention;

Fig. 7- shows' a circuit arrangement for the installation illustrated in Fig; 6;

Fig.8 shows the circuit arrangement for a'key telephone set including the shunt impedance means of this invention, whereby=: the key telephone: set may be restrlctedagainsti making out- With a. p-referred. coin colbers or screws I5.

on a. particular line or lines of the installation;

and

Fig. 10 shows the circuit arrangement involved in the installation of Fig. 9, in so far as concerns the application of the invention thereto.

With particular reference to Fig. 1, there are shown asubscribers substationsetor bell box HJ and a telephone set ll connected together through a telephone cord 12. The substation set comprises a cover member l3 secured to a back plate or mounting portion M by fastening mem- The cover supports a key-operated device or look. l6, of which more hereinaiter; has'an'aperture I 1 in a lateral wall for .entrance of the. cord; and has an aperture (not shown) in its"lower-' horizontal wall for the wirsubstation set'w'ith a telephone line.

going dial calls on one or 'more'ofithe lines with may be precluded from making outgoing dial calls 1' mg I8 containing conductors for connecting the phone set'comprises a mounting IS, a handset 20 comprising a transmitter 2| and'receiver 22, a calling 'd'ial or' signaling device 23, and a cord 24 for connecting the handset instruments with appropriate terminaLs in themounting.

'The telephone set is adapted to be supported on a.table, desk or other horizontal supporting surfaceata distance removed from the substation setdependent'on the length of the cord l2. The set -I ll may be adapted to be mounted on any suitable horizontal or vertical surface, for example, on a 'wall. under oron the side of a desk, or the like,'and, if'desire'd, may be located in an out- -of-the=ordinary or relatively inaccessible place.

Alternative telephone sets to the set H are identified byreferencecharacters H, l I". The

' set I I is of the so-calledhang-up typecomprising'a handset 20, a calling dial 23', a handset support or hook 25' cooperating with two pairs'of contact-springs (not shown) within the case or box-'26. The latter may be mounted on a suitable vertical surface by'a bracket 21. The set H"-is of the so-called desk-stand type comprisinga base portion 28 supporting a tubular standard ZB-"surmounted by a transmitter. A switchhook' 3fl supports a receiver and cooperates with contact springs. (not shown) in the standard. A callingdial 23" is mounted on the base portion.

Figj2'shows a circuit arrangement in accordance-with the invention that may be embodied in the substation set and telephone set of Fig. 1. The-substation set It! encloses a pair'of terminals 3!, 32 to which the telephone line conductors 33 of Wiring l8 are adapted to be connected, a two-winding induction coil 34,- a condenser 35, a ringer or station signal 36, an impedance 3'! consisting' of a silicon carbide varistor, a reactance,

or a resistor, a pair of

contact members

38, 38, and a key-controlled device or look I5 associated with the contact members for opening or closing thecontacts upon'key operation of the lock. The set H- provides a support and enclosure for the handsetZO, the calling dial 23 and two'pairs of normally open (that is, with the handset resting in the cradle of the mounting) contact springs 39, '40. "Theweight of-' the handset 011 the plunger member acting through suitable linkage'42 forces each pair of springs out of contact; removal of'the' handset enables the springs to engage. The dial comprises a pair of normally closedpulsing conta'cts'or springs 43, M, a pair of normally' open contacts or springs 45, i6, and iw paair of normally closed contacts or springs The two equipment assemblies are interconnected by the multiconductor cord [2 containing four conductors' fl, 50, til, 52. Conductor 49 con- The telenects line terminal 3| 'with the left spring of contact springs pair 39; conductor 5!], terminal 53 of the secondary winding of induction coil 34 with the left spring of contact springs pair 46; conductor 5 I, contact member 38'with the right spring of contact springs pair 39; and conductor 52, terminal 54 of the induction coils primary winding with dial spring 46. In the substation set, the remaining circuit connections are: condenser 35 is connected between line terminal 3| and terminal of the coil secondary winding, ringer 36 is connected between line terminal 32 and terminal 55, and impedance 31 is connected between primary winding terminal 54 and the contact member 38'. In the telephone set, the remaining circuit connections are: wire 56 connects right spring of contact springs pair 49 with dial spring 41 and wire connects right spring of pair 39 with dial sprin 43; the cord 24 comprises

conductors

51, 58, 59, of which

conductors

51, 58 connect the terminals of transmitter 2! with dial springs 44 and 46, one transmitter terminal being common to the transmitter and to the receiver.22, conductor 59 connecting the other terminal of the receiver to dial spring 48.

The circuit arrangement of Fig. 2 represents the normal or idle condition of the telephone station. If an incoming call is assumed, the station is signaled over a ringing circuit comprising the conductors 33, condenser 35 and ringer 36. Removal of the handset 20 from its support results in the closure of the springs of contact pairs 39, 40, those of pair 49 making or engaging last. This completes a talk ng or transmittin circuit that may be traced from conductor 33. terminal 32, primary winding of coil 34, terminal 54, con-- du'ctor-52, dialspring lfi, conductor 59, transmitter 2|, conductor 51, dial pulsing springs 44, 43, wire 60, contact pair 39, conductor 49, terminal 3', to the other conductor 33 of the wiring I8. Closure of contact pair 46 completes the following'receiving orlistening circuit bridged across the series-connected transmitter, dial pulsing springs, and contact pair 39: from terminal 3|,

condenser 35, terminal 55, secondary windingof 1 coil 34, terminal 53. conductor 56, contact pair 40, wire 56, normally closed dial sprin s 41, 43, conductor 59, receiver22, conductor 58, to dial spring 46.

To make an outgo ng call, the subscriber removes the handset 29 from its su port, thereby enabling closure of contact pairs 39, 49. The circuits traced in the preceding paragraph are completed. The subscriber then operates the dial 23 in accordance with the code for the party he desires to call. or for the operator. For each digit or letter dialed, the pulsing springs 43, 44 will break-and-make the number of times determined by the are through which the turnable element 3 of the dial has been turned. During such pulsing, dial springs 45, 46 are and remain closed while dial springs 41, 48 are and remain opened until the break-and-make ceases. Closure of springs 45,

46 during dial pulsing places a bridge around the.

transmitter, and the opening of

springs

41, 48

opens the receiver circuit. Such functioning of a for example, during a period or periods when he is not in its vicinity, he inserts a key into the lock l6 (which could be adapted to receive a specialshaped key) and locks the circuit against such use by causing closure or engagement of contact members 38, 38'. 'Ihis connects-the impedance 31 in bridge of or in shunt with the dial pulsing springs 43, 44 and the transmitter 2!, the shunt circuit being from terminal 54, through impedance 31,

contact members

38, 38, conductor 5| to the right spring of pair 39. The impedance is sufiiciently high in resistance to permit the transmitter 2| to remain substantially as effective for talking purposes, but sufficiently low in resistance to render dial operation ineffective, i. e., to short-circuit dial pulses. This action is aided by the use of an impedance with a negative resistance-voltage characteristic, such as a silicon carbide varistor. Since the transmitter is not affected appreciably by the presence of the protective short circuit, there is no impediment to the use of the station in responding to incoming calls. If the telephone station is connected in a dial system in which a sender monitor or dial system A operator is brought in on a connection after a certain time if dialing is not started, an emergency outgoing call could be made by anyone, since removal of the handset would complete a line circuit to the central office or exchange, and the operator would eventually cut in, and, satisfied of the emergency character of the call, completethe desired connection. The protective shunt circuit would be opened or disconnected by reverse operation of the lock l5. Although a key actuated or controlled device or look and spring contact members 38, 38' have been shown for closure and opening of the protective short circuit, it will be appreciated that any suitable device, for example, a combination lock involving suitable contact members, could be employed for this purpose.

Instead of being included in the set Hi, the protective shunt circuit could be housed in the set ll, contact member 33 being connected with right spring of pair 39 and the end of impedance 31 shown connected to terminal 54 being connected instead with dial spring 43. This would enable the use of a three-conductor cord between the sets H), H in place of the four-conductor cord l2. So located, however, the protective shunt circuit might be subject to more ready tampering by an unauthorized user intent on making a call using the calling dial. It will be understood, of course, that the impedance 3?, and the

contact members

36, 38 could be placed in an enclosure separate from either set ill or set H, and connected therewith to provide the protective circuit over a two-conductor cord. The arrangement described with respect to Fig. 2 appears at this time, however, to be a preferred one. In certain situations, as before stated. it may be found advantageous to employ a variable resistance for the impedance 3 1, for example, a unit having a negative resistance-voltage characteristic, for example a unit of silicon carbide.

Fig. 3' shows the invention embodied in a telephone station whose subscriber set l0 includes a three-winding induction coil 34, and separate condensers 35', 65 for the ringer and the receiver circuits, respectively. The induction coil 34' comprises a line or primary winding 61, a receiver circuit winding 62, and a balancing winding 63 to provide, with the receiver and transmitter, an anti-side tone circuit of the Campbell type. This circuit arrangement utilizes a five-conductor cord l2. for. interconnectin thesset, H) and set H. As mthea-arrangementof: Eig. ;2,;.the protective shunt circuit .is connected-between the transmitter end: of the primary-:windinsand the. right spring of pairi39, so..as.to;be connected in shunt with theseries-connected.transmitter and dial pulsing springs.

Figs. 6 and '7 illustratehow the: invention may be applied to a subscribers station-installation comprising a main telephoneset Zllilrand an-extension telephone. set 2M, eachprovidedwithaa calling dial 23. Set 208' is connected to the conductors of line 202 throughthe conductors-of cord 263 and connectorblock .204, and set 2G! through the conductorsof itscord ZEIS-and-the additional connector block 266 and cord or wiring 26?. diiferent places in, forexample, a store, anroffice or a. home, and it might be desired to-have the extension set normally disabled for or protected against unauthorizedoutgoing dial calls,

without restricting the maintelephone set 200.

This may be accomplished: by suitable connection in the circuit of the set Zill of the shunt impedance means of this invention over the conductors of cord 209, the connectonblockriilfi and a pair of the conductors of the. cord 205. The shunt impedance means'and its associatedzcontact members may be enclosed in any suitable container 2&8, positioned, for example. in the vicinity of the main setor at any preferred location. accessible to the subscriber or other authorized person. As illustrated in'F'ig. 6, the telephone set may be of the so-called combined set type, that is, the type in which .thecalling dial, induction coil, condenser or condensers, ringer,

switchin spring assembly and handsetare enmary winding 6|, transmitter 2| and dial pulsing springs 43, 44 that may be traced as follows! right spring of contact pair 39, conductor 2M1 of cord 205, terminal 2H of connector block 206, conductor 252 of cord 2B9, impedance 31, contact members 38, 38', conductor 2|3 of cord 2B9, terminal 2M of connector block 2% and conductor2i5 of cord 205 to the terminal 32 of the winding Bl. Dialing at the set 200 would remain unaffected when the handset 20 is in its cradle and the contact pair 39 in the normal or open position.

In a particular situation the'telephone set 20! might be provided on a'counter-or in a cashiers booth in a store where anyone might use the set for incoming calls but only authorized persons be able to use it for outgoin calls, the shunt impedance circuit being normally closed. It will be understood that a manually operated two-position switch could be substituted for the lock l6 and members 38, 38', and mounted in such a position behind the counteror in the cashiers booth that only those authorized to dialcalls could reach the switch to operate it. Another arrangement could involve a non-locking switch normally closing the shunt impedance circuit; it is apparent that this might be a foot-operated switch which could be held openiduring dialing and thereafter released or closed, thus providing a convenient and. inconspicuousv control means.

Thesets 2&0, ZBL-might be located at .S4 connected to th line L4.

It; will be understood, of-course, that the-; set.20l and the, shunt impedance circuit arrangement-associated with itcould comprise the, subscribers station installation,.that. is, the set Elli need not necessarily bean extension set of a stationyin stallation.

The invention may be embodied in a key telephone setadapted to pick up a. plurality (for ex ample, four) of dial central office or private branch exchange extension lines, or a combination ofboth. Fig. 8 shows a key telephone set 300 comprising handset'ZlLa calling dial '23, induction coil 34, switching contact pairs 39, 40, condensers 35and 65, ringer 36 and four-keys Kl, K2, K3, K4. connected: to lines LI, L2, L3 and L4, respectively, over'conduetor pairs Cl, C2, C3, C4, respectively. Each of keys KLKZ, K3 comprises a pairof inner normally closed contact sets I, 2 and apair of outer normally open con tact sets 3, 4. Key K4 comprises a pair of normally open contact sets 3, .4. The conductor pairs Ci, C2, C3,'C4 are connected to the outer contactsof the contact sets 3, 4 of the respective keys. Theringerand ringing circuit condenser for the set 300 may be connected across the line Ll. An impedance 31, illustrated as a varistor, is so connected by wires 30 l, 302 as to prevent dialing'out from the key telephone set over, by way of illustration, lines L3, L4. Wire Sol is connected with the right spring ofcontact set I of key K2 and with the left spring of contact set I of" key K3. Wire 3132 is connected with the right spring of contact pair 39. With the handsetZO removed from its supportand, consequently, with contact pairs 39, 4!), closed, and either key'K3 or-key K4 operated so that its contact sets 3, 4 are closed, a dial pulse shorting circuit in parallel with the series-connected contact set I of keys K2 and Kl, induction coil primary winding 6|, transmitter 2|, and dial pulsing springs 43,44 may be traced as follows: right spring of contact pair 39, wire 302, impedance?! and wire 30! to the right. spring of contact set I of ke K2. The impedance 3'l,'of course, would be proportioned to offer a low resistance to dial pulsing voltage when the dial pulsing-

contacts

43, 44 are opened but a high resistance to the relatively low direct current and voice frequency voltage drop across the induction coil primar winding 6|, transmitter 2| and dial pulsing springs 43, M in the talking condition.

In a particular installation it might be desired that dialing out from the key telephone set would normally be'possible on each of the lines with which the set is connected but that there be provision for preventing, if desired, dialing out on a particular line. The arrangement of Fig. 8 may be readily modified to this end. Let it be assumed that it isline L4 fr-omwhioh the key set is to be excluded-with'respect to outgoing calls from the key set, the exclusion to be under the control of a person at a point remote from the key'telephone set, for example, the user of the telephone The connection provided by wire 302 would be retained but wire 30! would be eliminated and replaced by .the wires 303,364 shown by dotted lines, wire 303 being'connected between the impedance 3'! and contact member 38, and wire 3% being connected between the contact member 38 and. the right spring of contact set I of key K3. Contact members 38 and 38' remain in open condition as shown until closed by rotation-of the cam'element 305. With

contact members

38 and 38 in open condition, itisobvious that there is'no short-circuit present with respect to the dialing circuit of the key telephone set. With

contact members

38, 38 in closed condition, however, the following circuit in parallel with the series circuit of dial pulsing springs 43, 44, transmitter 2|, induction coil primary winding BI and the contact sets I of keys Kl, K2 and K3 may be traced; the right spring of contact pair 39, wire 302, impedance 3'3, Wire 303, contact members 38, 38', wire 304 to the right spring of contact set I of key K3. An alternative connection for the wire 304 is indicated and designated 30 1.

Figs. 9 and illustrate how the invention may be embodied in a telephone secretarialsystem comprising a pair of principal or master stations Pl, P2 and a pair of secretarial stations SI, S2. The latter are adapted to be connected over conductor pairs Cl, 02, C3 and G4 with the telephone lines LI, L2, L3, L4 originating in a dial central ofiice or private branch exchange. The stations Pl, P2 are connected over conductor pairs 05, C0, respectively, with the telephone lines L3, L4, respectively, Each secretarial station may be similar to the key telephone set of Fig.8, corresponding components bearing like identifying characters, except as to the manner in which the impedance 3'! may be included in its circuit. In .Fig. 10, the impedance 3! is shown connected between the right spring of contact set 3 of key K4 and the right spring of contact pair39. This prevents the station Si from dialing out on line L4, i. e., it prevents the secretary of the principal of station Pl from dialing out on the line of the principal of station P2, althoug as a ready explained hereinabove, the-station SI is not precluded from picking up a call incoming on line L4; By including in the telephone set of station Pl a pair of contact members 38, 38', normally in open condition, as shown, and adapted to be closed by rotationof the cam member 305 on turning the button 300 from its "01? to its fon position, the principal at station Pl may exclude his secretary from dialing out on his line, i; e., on line L3, so long as the button 306 is adjusted to its on position. Conductors or

wires

301, 308

/ of the cord 300 connect the contact members 38,

38', to the spring common to contact sets I, 3 of key K3 and to one terminal of the impedance 3]. With contact members 38, 38' in closed condition, with handset removed from its support and key K3 operated so as to open its contact sets I, 2 and close its contact sets 3, 4, the dialpulsing circuit is short-circuited through the contact members 38, 38' over the following circuit: key K3 contact set 3, conductor 301, members 38, 38', conductor 308, impedance 3'! and contact pair 39. It will be apparent that in the key telephone set of station S2, the impedance 3'! included therein would be so connected as to short-circuit dialing out through its key connected to line L3, and that the conductors of cord 309' would be connected so as to short-circuit dialin out through the key of station S2 connected to line L4. Thus, the station S2 normally would be precluded from dialing out over the line L3 of station Pi, and could be'pi'ecluded by the principal at station P2 from dialing out over the latters line L4,

Figs. 4 and 5 illustrate the application of the invention to pay telephone or coin collector stations.

, Pay station telephones that include a calling dial are frequently arranged so that it is necessary for a calling party first to deposit a coin before dialing in order to establish connection with the operator at the central ofiice, or with the called party. The arrangement i such usually that the deposit of the coin causesclosure of the line circuit to the central oflice so that operation of the calling dial at the pay station causes transmission of dial pulses over the line to pulse-actuated relays or switching device at the central oiiice or exchange, Ior completion of the connection in accordance with the code dialed. Should the calling party somehow be able to complete the line circuit without the deposit of a com, the company or individual operating the pay station might be defrauded or deprived of revenue to which it is entitled. To obviate this possibility, it has already been proposed that the pay station circuit be arranged so that, until a coin has been deposited, the pulsing springs of the calling dial are short circuited. Deposit of the coin not only completes the hue circuit but also removes the short circuit on the dial pulsing springs. Accidental or fraudulent completion or the line circuit in the absence of the deposit of a coin becomes, then, of no utility so far as effective use of the calling dial is concerned.

In that type of pay station in which the transmitter and the calling dial are supported on the housing or enclosure ior the coin chute or runway, the coin signals, the coin collect and refund relay and the coin box, and the receiver is supported on a switchhook carried by the hOuS- ing, the location of the transmitter enables it to convey to the operator, in situations Where the operator needs to be informed of the amount being deposited at the pay station by a calling party, the characteristic sounds associated with the deposit of coins of particular denominations. In pay stations otherwise the same as that of the preceding paragraph, but in which the transmitter is included with the receiver in a hand telephone set or handset supported on the switchhook, the transmitter is no longer advantageously located for picking up the mechanical and acoustical vibrations arising from the depos.t of the coin or coins, and a coin signal transmitter'or microphone has been included in the pay station for the sole purpose of conveying the coin deposit characteristic sounds or vibrations to the operator.

A general practice'with respect to pay station telephone setshas been to arrange the components of the set on a pair of interfitting housing portions, all electrical connections between the housing portions being efiected through a plurality of contact members or spring on one housing portion adapted for frictional engagement with a corresponding plurality of contact members or prongs on the other housing portion. With such an arrangement, the interfitting housing portions may bereadily separated or disassembled without the necessity of disconnecting or breaking wires,or of reconnecting wires when the housing portion are again assembled. In the interest of cost and space economy and of circuit simplicity, the endeavor has always been to keep the number of these interconnecting contact members to a minimum.

The arrangement of L. H. Allen Patent 2,262,- 571 of November 11, 1941, i illustrative of a pay station telephone of the type referred to in the third preceding paragraph. In the Allen arrangement, four contact members 29 on the one housing portion or cover 24 engage with four

contact members

43, 44, 45, 46 on a second housing portion 32 and the dial pulsing short-circuiting mean (contact spring 63, 64) of the coin collect relay is connected across a pair of contact members '44, 45 on the second housing-pertion 32.

The arrangement of O. A; Shah-net al. Patent 2,235,648 of March 18, 1941, is illustrative-of a pay station telephone of the type referred to in the second and third preceding paragraphs With reference to Fig. 2 of the Shann et-al. patent, it will be seen that the inclusionof-the two coin signal transmitters l6; IT or "of a single coin signal transmitter 6i 1 requires that fivepairs-of contact members-4l i5 be provided to interconnect the components ontheinterfitted housing portions. The circuit arrangement of the Shann et a1. patent does not include any-means for normally short-circuiting' the" dial pulsing springs. When it is'desiredthat'the' Shannet a1. circuit arrangement also include provision -for rendering the calling dial ineffective fof'trans mission of dial pulses until-after a-coinds'deposited by the calling subscriber; it might appear that the expedientof the Allen-patent cou-ld be readily incorporated.- It'willbe observed; however, that not only-would the dial pulsing spring-s be shunted, so'would'the coin-signal transmit ter. Consider the following situation: The call ing party has deposited a coin and, hence, has been able to dial the operator at the central ofiice. Theoperator inform the calling party that she is returning thedeposited coin; and that he should deposit a specifiedamount: The return of the-coin restores the-two pairs 'ofre-la'y contacts to their-normal condition. When the calling party deposits I the coin representing the specified amountor the first of the number of coins required to make up the specified amount, the dial pulsingsprings: andthe coin signal transmitter will be short-circuit'ed. Since the coin signal transmitter will not be eifective to transmit the characteristic vibration 1 of a deposited coin until after the first coindeposited" has*-disabled the shunt onthe-coin signal-transmitter, the operator will have-no information as' tothe denomination of the fi rst' or only coin deposited. This undesirable 'condition could-be obviated by an arrangement that short-circuits only the dial pulsing springs. The" coin-relay con-tact-s'etfor short-circuiting the pulsing springs could b'ecom nected across the:pulsingsprngs only by providing asixth pair of contact members 'foriiiter connecting. the pay stationcomponent on the housing portions; This latterexpedient, however, is in the-direction'or increasing the numberof interconnecting contact members on the ho'uslng portions.

In accordance with the invention, the pay Station telephone, ingeneralsimilar to that ofthe O. F. Forsberg Patent: 1,043,219 ofNoverhber'S, 1912, but whose coin collect and refund relay in cludes an additional pair of-contact springs; for example,-as provided in theAllenpat'ent; and which includes the handset; coin'runway, coin signals and the single-coin signal transmitter arrangement of the Shann et a1. patent, has'its components arranged so that the coinsignal transmitter and the pulsing-springs 0f the calling dial are connected in series with a pair of'contact members on one ofthe-inte'rfitting housing portions of the'pay station, and-theadditional pair of contact springsof the coin relay are lncluded in anormally closedbridging or shu'nting circuit connected between" the pair of contact members on the other housing portion that engages the first-mentionempair of contact-meme bers when the housingportionsare-interfitted or assembled. The bridging. circuit includes an im amazon ped'a'nce element of'such resistance that, although dial pulses are effectively short-circuited or prevented from being transmittedfromthe station while the before-mentioned coin'relay contact springs are closed, the resistance is sufficiently large compared to that of the coin signal transmitter so as substantially not to interfere with transmission from the station by the coin signal transmitter of currentcharacteristic of coin signal vibration resulting from the deposit of a coin and before the coin relay contact springs are effected by the deposited coin. The impedance element may be a so-called constant or linear resistance, or may be of the type having a negafive-resistance voltage characteristic, for example, a silicon carbide unit.

Fig, 4 illustrates a typical pay telephone or coin collector station. It comprises a coin collector 10 and a subscribers set or bell box H. The coin'collector comprises a cover, front or upper housing portion 12, and a back plate or rear housing portion 13, the lower portion of the latter comprising a casing 14 for a coin box (not shown) and a coin return chute 15-, the cover portion beingremovable as a unit from the rear portion; The-cover includes a coin slot or guide 16 and supports a calling dial 23. A. hook or support 11'carried by the back plate 13 supports a handset 20, the cord 24 'for which extends through a suitable aperture (not shown) in'the back plate into the interior'of the coin collector. The components in the set 1| are connected with the components of the coin collector through the conductors of cord or Wiring 18, connection to a telephone line being made through the conductors ofa cord or Wiring 19.

In Fig. 5, the area bounded by the broken lines ABCD represents the coin collector rear housing portion 13, that bounded'by the broken lines DEFG represents the-coin collector removable cover portion 12, and that bounded by broken linesMNOR represents the set 1|.

The coin collector components include the call-'- ingv dial 23, a coin signal microphone or transmitter 80, anda plurality of contact members or prongs-8i, 82, 83,- 84, mounted on the cover portion 12 which would also provide a support for a multiple runway coin chute anda plurality of coin actuatable or vitratable coin signals, for examplesuch as is disclosed in the Forsberg or the Shann et al. patents. Additional components are'mounte'd on the rear portion 13 and comprise a coin collect and refund relay 86 including two sets 81, 88 of contact springs, one set 81 being normally open and the other set 88 being normally closed, and being adapted to close and to open, respectively, when a coin is deposited at the station; the switchhook 89 providing a support for'the handset 20; two sets 90, I00 of contact springs associated'with the switchhook and adapted to close when the handset is off the switchhook; a plurality of contact members,

blades or springs 9|, 92, 93, 94, whose free end portions are adapted to befrictionally engaged by serrated end portions of the contact prongs 8l--85,.respectively;. an induction coil or transformer 98; a condenser 91; and an impedance element 98. The transformer comprises a twosection or mid-tapped primary winding i It, a receiver circuit winding Ill and a balancing network or Winding H2 proportioned to provide, with the transmitter 2i and-receiver 22 of handset 20, an anti-sidetone circuit of the Campbell type. The primary winding is provided with central terminal H3 between-which and ground the coin collect; relay 86 is adapted to be connected, in accordance with the teachings of W. H. Edwards et a1. Patent 2,024,280 of December 17, 1935. The element 98 is a resistor, either a socalled constant or linear resistance, or, in a particular case, of the type having an asymmetrical or non-linear resistance characteristic, for example, a silicon carbide unit. The handset 20 and its associated cor-41.24 may be the same as those of the arrangements of Figs, 2 and 3, as may be, also, the calling dial, corresponding parts bearing like reference numerals. Coin signal bell 99 and gong IOI are indicated in dotted outline above the coin relay in the area ABCD, although they would actually be supported on the cover p tion I2. The set II contains only the station signal or ringer I02 and blocking condenser I03 connected in series between terminals I04, I 05, and may be located, if desired, at a point remote from the coin collector, and with the conductors I06 of the cord 78 concealed. I

The circuit connections are as follows: The telephone line 79 connecting the paystation with a central oflice or exchange is connected to terminals I04, I05 of the bell box. Conductors I06 of cord or wiring 78 are connected with terminals I I4, I I 5 in the coin collector, the former also constituting one terminal of the coil winding H0.

The conductor I06, terminated at terminal II5 could, of course, be of sufiicient length to terminate at the left spring of pair I00, thereby obviating the need for terminal I I5 and wire I25. Transformer terminal I I6, common to the primary and the balancing windings, isconnected by conductor 59 of cord 24 to one terminal of transmitter 2|; transformer terminal 'II'I, common to the balancing and the receiver circuit windings, is connected by wire I I8 to left spring of pair 96; transformer terminal H9 is connected through condenser 91 with contact member 9|; and transformer terminal H4 is connected by wire I to contact member 93. Cord conductor 51 connects the second terminal of transmitter ZI with contact member 9I, and-cord conductor 59 connects one receiver terminal to contact member 95, the other receiver terminal, as indicated, being ,the first-mentioned transmitter terminal. The right spring of pair 90 is connected with contact member 94, and the right spring of pair I60 is electrically unitary with contact member 92. A series circuit comprising wire I2I, the normally-closed relay contact springs 58 and the impedance 98 is connected between contact members9l, 92. The coin signal microphone 80, which may be similar to that of A. F. Bennett Patent 1,863,322 of June 14, 1932, is connected between contact prong 8| and dial pulsing spring 44, dial springs 43, 45, 41, 48 being connected with

contact prongs

82, 83, 84, 85, respectively. It will be observed that, as shown in Fig. 5, the series circuit including the impedance 98 is connected in shunt with or in bridge of the series-connected coin signal transmitter and dial pulsing springs between contact prongs BI, 82 that engage with contact members 9|, 92, respectively.

As shown the pay station telephone of Fig. 5 is not in use. Let it be assumed that a calling party wishes to make a local call, that is, one that does not require the operator at the central oifice or exchange for the station to come in on the call. The removal of the handset from the hook or sup-port 89 enables the closure of the contact pairs 90, I00, and the deposit of the appropriate coin I90 by the calling party trips the trigger I of the coin relay and the contact sets 81, 88 of the coin relay close and open, respectively. The closure of contact set 81 places ground on one line wire of the cord "l9 over the coin relay winding, that portion of the transformer primary Winding between terminals H3, I I 4, one conductor I06 of the cord I8 and terminal I04, and enables, in known manner, the operation of the line relay at the central ofiice and the seizure of the line by a line finder. The opening of contact set 88 removes the bridge or short-circuit on the series connected coin signal transmitter 80 and dial pulsing springs 43, 44. Closure of the switchhook contact pair I69 completes the following circuit across the terminals I04, I05; terminal I04, conductor I06, transformer primary or line winding H0, conductor 58, transmitter 2i, conductor 57, contact memher and prong 9i, 8|, coin signal transmitter 86, dial pulsing springs 44, 43, contact prong and member 82, 92, contact pair I00, wire I25, conductor I06 to terminal I05. Closure of switchhook contact pair 90 completes the following bridge across the transmitter 2| common terminal of transmitter 2I and receiver 22, receiver 22, conductor 59, contact member and

prong

95, 85,

dial springs 48, 47, contact prong and

member

84, 94, contact pair 90, wire IE8, transformer winding I II, condenser 97, contact member 9i, conductor 57, back to the other terminal of transmitter 2I. During the dial pulsing, dial springs 45, 46 are closed thereby short-circuiting the coin collector circuit, and springs 41, 48 are disengaged thereby opening the receiver circuit. The dial pulsing circuit between terminals I04, I05, is as follows: Terminal I 04, conductor I 06, wire I20, contact member and prong 93, 83, dial springs 46, 45, dial pulsing springs 44, 43, con- I tact prong and member 82, 92, contact pair I00,

wire I25, conductor I09, to terminal I05, After the calling party has restored the handset to the switchhook and the relay has been operated to dispose of the coin, the pay station circuit is again in the condition shown in the drawings.

Let it be assumed that the calling party is endeavoring to defraud the company or individual providing the coin collector service and, without depositing the requisite coin or token, somehow is able to connect the coin relay line conductor to ground so that, if the bridging circuit including contact set 88 and resistor 98 that requires connection with the operator and the subsequent deposit of a specified amount at the operators direction. The operator, of

course, must be able to determine at her remote position that the specified amount is deposited. To establish connection with the operator, after removal of the handset, the calling party deposits a coin or taken at the station and dials the appropriate code. The operator responds and after ascertaining the connection desired by the calling party, informs the latter of the amount to be deposited and by application of current of appropriate polarity to the coin relay line conductor, operates the coin relay so as to return the coin the calling. party has. alreadydeposited: and to restore the coin relay :to:the"condition shown on the drawings.

Before the first or perhaps the only win to'sb'e deposited by the callingv party, aiiects theTCOHdl tion of the coin relay contact sets -81, 88, it strikes once or more against one .or moreot the coin signals thatis, bell orspiral gong, asiitzpasses down the coinrunway to the hopper of the coin collector. It is not until the coin operates the trigger projecting through the coin hopper that the contact set 88 opens to remove theshunt across the coin signal microphone and the dial pulsing springs. In the absence of the resistor 98, the coin signal microphone Would not be eflective to pickup the characteristic vibration of the coin'actuated signal until the first coin has already passed the signal. By choosing an appropriate magniture of resistance for resistor 98, the shunt circuit will be ineffective substantially to affect the effectiveness of the coin signal microphone in the assumed situation, while remaining eitective to prevent fraudulent operation of the pay station and its calling dial,v that is, dial pulsingis effectively short-circuited but not coin signal transmission; This resistance, depending. upon the handset transmitter and the coin signal microphone employed, may be of the order' of about 100 to 200 ohms and less than about 500 to 1000 ohmsv so long as the battery supply loss introduced 'byit is not excessive and the alternating current output of the coin signal transmitteris reduced only slightly from What it would be iithe bridging circuit were not present.

In some circumstances-it may be found desirable to replacethe resistor 98 with 'a variable resistance device or unit. If pulsing battery of 24 or 48 volts at the central office is assumed, the variable resistance would be arranged so that when the pulsing springs of the dial were opened, but with relay contact set88 closed, the resistance would assume a low-value *therebyeffectively to short-circuit the dial pulses. So far as the coin signal microphone is concerned, with the pulsing springs closed, the potential across it would be comparatively low in which case the variable'resistance would have a comparatively high resistance and have no substantial effect on the coin signal microphone.

The inclusion of the induction coil andcondenser within the coin collector-instead of housing'them in the bell box, has various advantages. The number of wires or conductors requiredbetween the coincollector and the bell box is'reduced to two and at the same time provision may be made readily in the coin collector for the balanced circuit'connection for the coin relay and induction coil to regulate the inductive susceptiveness of the circuit, and forthe short-circuiting of the induction coil primary winding during dialing with a minimum size loop betweenlthese' ele-. ments due to their physical proximity thereby decreasing the radiation of radio frequencies during dialing, The arrangement, furthermore, permits of greater flexibility in mounting the coin collector and the bell box primarily, from the standpoint of improving the appearance of installations that are not in a booth or other enclosure; It will be'observed, also, that the wiring required within the coin collector isrelatively of simple character.

Although this invention has been disclosed withreference to what are believed at this timetobe preferred embodiments, itwill be understood'that it:is notlimitedz thereto, but is of. a. scope. evidencedby the appended claims;

What .is claimed is:

1. A telephone station circuit comprising. a transmitter, a calling dial including a pair of pulsing contacts connected in series with said transmitter, and means to protect said circuit against unauthorized use, said means comprising a circuit to-be shunted across said'seriesconnection to disable 'said. calling dial without. disabling said transmitter.

r 2. A telephone station circuitcomprising a transmitter, a calling dial including a pair of pulsing contacts connected in series with said transmitter, and meansto protect said circuit against unauthorized use,- said means comprising a circuit'to be shunted across said series connection to..disable.said calling, dial without disabling said; transmitter and disconnectable therefrom only by; an authorized user.

3. A telephone station circuit comprising a transmitter, a calling dial including a pair of pulsing contacts connected in series with said transmitter, and means to protect said circuit against unauthorized use, said means comprising a circuitincluding an impedance to be shunted across said series connection to disable said calling. dial without disabling said transmitter.

4. A telephone station circuit comprising. a transmitter, a calling'dial includinga pair of pulsing. contacts connected in series with said trans mitter,and means to protectsaidcircuit against unauthorized use, said means comprising a circuit including a resistance tobe shuntedacross'said series connection to disablesaid calling dial without disabling said transmitter.

5. A telephone station circuit comprising a transmitter, a calling dial including a pair of pulsing contacts connected in series with said transmitter and means to protect said circuit against unauthorized use; said means comprisinga circuit including a'varistor shunted across saidxseries connection to disable said calling dial without disabling said transmitter.

6. A. telephone station circuit comprising a calling dial and atransmitter, said calling dial including a pair of pulsing-contacts connected in series with said transmitter, a normally open circuit connected in shunt with said series con nection and including an impedance, and means to close-said shunt circuit.

'7. The circuit of claim' 6 i which, when said shunt circuit is closed, said impedance renders operation of said dial ineffective to transmit signal pulses without substantially affecting the efiectiveness of said transmitter.

8. A telephone station circuit comprising a calling dial and a transmitter, said calling dial including a pair of pulsing contacts connected in series with said transmitter, and a circuit connected in shunt with said seriesconnection and including an impedance, said impedance render ing operation of said dial inefiective to transmit signal pulses and having substantially no effect on the effectiveness of said transmitter.

9. A telephone. station circuitv comprising a calling dial and a transmitter, said calling dial lIlClllCllllg apair of pulsingcontacts connected in series with said transmitter, a circuit. connected in shuntwith said series connection and includ ing a resistance, said resistance being propor tioned to render operation of: said dialineffective to transmit dial pulses but having noappreciable efiect. on the effectiveness of said transmitter,

and switching means to open and close said shunt circuit.

, v 1-0. In combination, an equipment h assembly comprising a receiver, a transmitter, a calling dial including a, pair of pulsingcontacts, anda pair-of contact springs; a second equipment as sembly comprising an induction coil, an impedance, a pair of contact members, and a pair of line terminals; and a multiconductor cord for connecting .said assemblies; one winding of said induction coil, two conductors .of said cord, the pulsing contacts of said dial, said contact springs and said transmitter being connected in series between said line terminals; and said ,impedance, .said contact members and a third conductor of said cord being connected in series with each other and i shunt with said dial pulsing contacts and said transmitter.

11. In combination, an equipment assembly comprising a transmitter, a calling dial having a pair of pulsing contacts, and a .pair .of contact springs; a second equipment assembly comprising an induction coil, a resistor, a pair of contact members, and a pair of line terminals; and a multiconductor cord for connecting said assemblies; one winding .of said induction coil, two conductors of said'cord, said contact springs, the pulsing contacts and said transmitter being connected in series between said line terminals; and said resistor, said contact members and a third conductor of said cord being connected in series with each other and in shunt with said dial contacts and said transmitter.

12. In combination, an equipment assembly comprising a transmitter, a calling dial including a pair of pulsing contacts, and a pair of contact springs; a second equipment assembly comprising an induction coil, a resistor, a pair of contact members, and a pair of line terminals; a n'iulticonductor cord for connecting said assemblies; one winding of said. induction coil, two conductors of said cord, said contact springs, the pulsing contacts and said transmitter being connected in series between said line terminals; said resistor, said contact members and a third conductor of said cord being connected in series with each other and in shunt with said dial contacts and said transmitter; and means to open and to close said contact members whereby said shunt circuit may be opened and closedto remove and retain respectively said resistor in shunt with said dial springs and said transmitter.

.13. A telephone station circuit comprising a calling dial and a transmission device, said calling dial including a air f pulsing contacts connected in series with said device, and pulsing contact disabling means adapted to be bridged across said contacts and said device without disabling said device when disabling-said pulsing contacts.

14. A telephone station circuit as claimed in claim 13 in which said disabling means includes an element offering a low impedance to dial pulse currents and a high impedance to transmission device currents.

15. A telephone station circuit comprising a calling dial including a pair of pulsing contacts, a transmitter relatively closely associated physically with said calling dial, and pulsing contact disabling means relatively distant from said transmitter and dial, said means being adapted to be bridged across said contacts and transmit-- ter, without disabling said transmitter when disabling said pulsing contacts.

16. A telephone pay station comprising a handjing circuit upon the deposit of a coin at the station.

i7. A telephone pay stationas claimed in claim 1-6 in which said shunting circuit includes an impedanceof a magnitude suflicient to short- .circuit dial pulses without having any substantial efiwton said vibrationtranslating means.

518. Atelephone pay station as claimed in claim 16in which said shunting circuit includes a resistance element.

.9.. A telephone lpay stationicomprising a handset, a d i m dial having ,a pair of pulsing conta t for yt lansmittingsignal pulses from said station, a coin vibratable signal, means connected in series with said contacts for translating vibrationsof the Signal into a characteristic current for transmission girom said station, a shunting circuit bridged, across said contacts and said vibration translating means to render said contacts inoperative for signaling purposes until a coin has h end nosited at. the stations, and coin ao uat'a le means to disable said shunting circuit upon the deposit of a coin at the station, said shunting circuit including .a variable resistance evice. V

(20. A telephone pay station comprising a handset, stalling dial having a pair ofpulsing con.- tactsfor transmitting s gnal. pulses from said station, ,a coin vibra-table signal, means connected in series withsaid contacts for translating vibra- .tions Ofthe signal into a characteristic current ,for transmission from said station, a shunting circuit. bridged across said-contacts and. said vibration translating means to render said contacts inoperative for signaling purposes until a coin has been deposited at the stations, and coin ,actuatable means :to disable said shunting circuit upon the deposit of acoin at the station, said shunting circuit including a unit of silicon carbide.

21. A -telephone Day station as claimed in claim 16in which said shunting circuit comprises a pair set, a calling dial having a pair of pulsing conofenormally closed contacts in series with impedance. a

22. A telephone pay station comprising a calling dial having a pair of pulsing contacts for transmitting signal pulses from said station, a coin vibratable signal, means connected in series with said contacts for translating vibrations of the signal into a characteristic current for transmission from said station, a shunting circuit bridged across said pulsing contacts and said vibration translating means to render said contacts inoperative for signaling purposes until a coin has been deposited at the station, and coin actuatable means to disable said shunting circuit upon the deposit of a coin at the station.

23. A telephone pay station comprising a calling dial having a pair of pulsing contacts for transmitting signal pulses from said station, a coin vibratable signal, means in series with said contacts for translating vibrations of the signal into a characteristic current for transmission from said station, a shunting circuit bridged across said pulsing contacts and said vibration translating means to render said pulsing contacts inoperative for Signaling purposes until a coin has been deposited at the station, said shunting circuit being without any substantial efiect upon the effectiveness of said vibration translating means, and coin actuatable means to disable said shunting circuit upon the deposit of a coin at the station.

24. A telephone pay station comprising line terminals, a handset, a switchhook for said handset, a coin collect relay including two contact sets; one contact set being normally open and the other normally closed, two sets of switchhook contacts, each switchhook contact set being open when the handset is on the switchhook and being closed when the handset is off the switchhook, a calling dial including a pair of pulsing contacts, a coin deposit signal, a coin deposit microphone, a plurality of contact prongs, a plurality of contact springs, said microphone and said dial contacts having all their circuit connections made to each other and said contact prongs, and said handset and line terminals having circuit connections to said switchhook contacts and said contact springs, and a bridging circuit for said microphone and the contacts of the dial, said bridging circuit terminating at a pair of said contact Springs and including the normally closed contact set of the relay.

25. A telephone pay station comprising a handset, a calling dial having a pair of pulsing contacts for transmitting signal pulses from said station, a coin vibratable signal, means in series with said dial contacts for translating vibrations of the signal into a characteristic current for transmission from said station, a shunting circuit bridged across said contacts and said vibration translating means to render said contacts inoperative for signaling purposes until a coin has been deposited at the station, and coin actuatable means to disable said shunting circuit upon the deposit of a coin at the station, said coin vibratable signal and said coin actuatable means being positioned such that upon the deposit of a coin at the station, the deposited coin acts first on said signal, and said shunting circuit being of an impedance efiectively to short circuit the dial contacts without" having any substantial effect upon the coin signal vibration translating means.

26. A telephone pay station comprising a housing having a plurality of interfittlng portions, each portion supporting some of the components of the circuit of said station and all of the electrical connections between the components on said portions being effected through a plurality of contact prongs on one portion adapted, when the portions are interfitted, frictionally to engage a corresponding number of contact springs On another portion of the housing, a coin deposit microphone and a calling dial having a pair of pulsing contacts supported on said one housing portion, said microphone and said dial contacts being connected in series between a pair of said contact prongs, means on said other housing portion connected between the pair of contact springs corresponding to said pair of contact prongs to shunt said series-connected microphone and dial contacts, said means including a pair of normally closed contacts, and coin actuatable means responsive to the deposit of a coin at the station to open said normally closed contacts and to remove the shunt around said series-connected microphone and dial contacts.

27. A telephone pay station comprising an equipment assembly having a pair of line terminals, a coin collect relay comprising an energizing winding and including two pairs of contact springs, one pair being normally closed and the other normally open, one spring of the latter being connected to ground and its second spring being connected through the relay winding to oneof said line terminals, a handset, a support for said handset, two pairs of switching springs, each pair of switching springs being open when the handset is on said support and closed when the handset is off said support, and a plurality of contact blades; and a second equipment assembly comprising a coin deposit micro phone, a calling dial and a plurality of contact prongs, all electrical connections between said equipment assemblies being effected through frictional engagement between said contact blades and said contact prongs, said microphone and the pulsing contacts of said dial being connected in series between a pair of said contact prongs, a circuit connected in bridge of the series-connected microphone and pulsing contacts and including said normally closed springs of the relay, the bridging circuit being terminated at that pair of contact blades engaged by said pair of contact prongs.

WILLIAM H. EDWARDS. OSCAR A. SHANN.