PL20128B1 - Automatic telephone device. - Google Patents

Description

This invention relates to telephone devices, and more particularly to automatic telephone devices. The general subject of the invention is an improved automatic telephone device in which the automatic switches operate more precisely under the influence of control pulses transmitted to them. The switch control pulses, sent from the automatic telephone device on the calling telephone line, actuate, as is known, a line relay connected in series with the line. Due to variable conditions (caused, among other things, by differences in resistance and insulation leakage of individual lines connected to the automatic telephone exchange), it is difficult to keep the line relay in the automatic switchboard in a state regulated so precisely that it operates faithfully and without distortion under the influence of impulses received from all lines. If the line relay is very sensitive, that is, if it responds accurately to impulses received from long lines, then this relay will remain in the active state too long in the case when the said impulses come from short lines. To avoid this, according to the invention, a cathode ray tube is placed between the line and the automatic switch instead of the relay used so far, because it has been found that by means of such a tube it is possible to obtain essentially the same changes in the anode current with very large changes in the grid potential. To achieve this, the grid of the cathode ray tube used in the present device is connected to the conductor of the output line of the automatic switch in order to receive the incoming impulses, e- The electromagnets driving the switches are controlled in accordance with the anode current of the lamp, which starts and stops operating depending on the pulses reaching the lamp's grid. According to one embodiment of the invention, a cathode ray tube is placed in each automatic switch, receiving the pulses, and the electromagnets driving the switches are connected directly to the anode circuit of the lamp. According to a second embodiment of the invention, repeaters in the form of cathode ray tubes are placed between the calling telephone lines and the automatic switches. These repeaters receive all incoming pulses and transmit them to the various automatic switches via standard line relays located in the automatic switches. Line repeaters used in automatic switching devices therefore operate accurately because they always operate under the same conditions and are not influenced by line conditions that vary within wide limits, as is the case when relays are connected directly to the calling lines. A further subject of the invention is a pulse repeater in the form of a cathode ray tube, which in normal automatic telephone devices can be used as an output repeater instead of the existing output repeaters in which line repeaters are used. This repeater is very advantageous in multi-station telephone devices where the lines are not heavily loaded and where line relays operate when connected directly to the line but not operate properly when activated by electromagnetic pulse repeaters during interstation calls, often using long cable lines. All difficulties connected with the use of cathode ray tubes in individual circuits have been completely overcome according to the invention, namely, the lighting and extinguishing of cathode ray tubes has been achieved here by means of appropriate circuits, the correct normal grid potentials of these tubes have been obtained, and the circuits necessary for performing the appropriate normal supervision have been prepared. Figs. 1-4 of the drawings show the usual circuit arrangements of only that part of the telephone device in which the subject of the present invention is used, because only this part is needed for the realization of 1 and 2, after folding Ldh, show the connecting device and the control device effecting the connection between the calling device A1 I at one station and the called device BI at the other station. The line switch LSI used in these devices may be an ordinary rotary line switch, usually used in automatic telephone devices. The station selector OSI is a vertical rotary selector with horizontal contact pads. The thousandth and hundredth selectors ThS1 and HSI may be mechanical, being electrically similar to the station selector OSI; the switch C1 may be of the same type, but may have a mechanism In order to reduce the resistance of the circuit through which the speaker current is supplied to the calling line during inter-station calling, to avoid the possibility of using the third conductor in inter-station connections and to facilitate the transmission of inter-station pulses from the station selector OSI to the outgoing cable line consisting of conductors 141 and 142 running to the distant station and terminating in the input thousandth selector ThS1, the device is provided with a repeater R1. Fig. 3 shows the circuit arrangement in a multi-station device, similar to the device shown in Figs. 1 and 2, but differing in that in cable line, between the line switch LS2 and the station selector OS2, a pulse repeater R2 in the form of a cathode ray tube is connected, and all the connecting devices are of a standard construction and are equipped with ordinary line relays, such as, for example, the line relay 331 of the station selector OS2. The pulse repeater lamp, shown in Fig. 4, which sends pulses received directly from the incoming line to the outgoing line without using a repeating relay, can be placed before the first station selector, as shown in Fig. 3, or it can operate in the same way as the output repeater, as is the case with the repeater R1. (Fig. 1). Repeater R3 according to Fig. 3, similarly to repeater R2 according to Fig. 4, repeats and forwards the pulses to normal switches in which line relays are used. The operation of the devices (shown in Figs. 1 and 2) will now be described. For this purpose, it is assumed that the subscriber of the telephone set A1 belonging to the first station wishes to talk to the subscriber of the telephone set B1 of the second station. Subscriber A1 takes his handset off the hook and dials the digits of the telephone number of subscriber B1. After removing the handset of the telephone set A1, the line switch LSI starts to operate, extending the line wires 2 and 3 to the first free station selector. Let the first free station selector be selector OSI. This selector is connected to the device A1 and, by means of brushes 101-103 of the line switch Lsl via conductors 104-106, whereby relay 107 is excited in the following circuit: earth, battery, resistor 123, conductor 104, brush 101, loop of device A1, conductor 2, brush 103, conductor 106, resting contact, lower winding of relay 107, resistor 116 and earth. The excited relay 107 grounds cable conductor 105 at its upper arm in order to protect the selector from the influence of other line switches and to close the normal circuit (not (included), stopping the line switch LSI, closes at its lower armature the glow circuit of the cathode ray tube 121, which runs from ground through resistor 122 and the internal lower armature of relay 110 to an ordinary central battery. Simultaneously, relay 107 breaks the circuit of the release electromagnet 115 to prevent premature operation of this electromagnet. After the lamp 121 is ignited, an anode current appears in the circuit comprising relay 108, vertical electromagnet 113, and an anode battery, grounded at the negative pole. The grid of lamp 121 receives a large initial negative potential as the voltage drop across resistor 116. The anode current of the lamp 121 excites a vertical electromagnet 113, which on its armature eliminates the short circuit of the upper winding of relay 107, as a result of which the relay 3 remains excited (by means of its upper winding independently of the lower winding), and therefore remains excited during the sending of a series of pulses. Thanks to this, the linear current can have the intensity only necessary to initially excite relay 107, in order to close the glow circuit of lamp 121, after which the circuit of the upper coil of this relay is switched on, maintaining its excitation. The upper coil of relay 107 is shunted by a resistor 117, so that the local current is not interrupted after the short circuit of the upper coil circuit. After short circuiting of this circuit, the relay 107 demagnetizes slowly. It should be noted that the central battery usually has a voltage of 46 to 50 volts, while the filament of the lamp 121 requires, depending on the type of this lamp, from three to seven volts, so that the average potential of the filament of the lamp 121 differs only by a few volts from the earth potential. As a result of activating the disc of the device A1, the linear circuit is interrupted a certain number of times (corresponding to the value of the first digit of the given number). Each time this circuit is interrupted, i.e. after removing the negative potential, which is applied to the line by means of the conductor 104 in the manner already described, the grid of the lamp 121 receives a positive potential in relation to the filament, because it is then grounded via lower coil of relay 107 and resistor 116. Therefore, each time the anode current increases, thereby exciting relay 108. Each time the line is closed again by the telephone calling device A1, the current flows again along the line, and the grid potential of the lamp 121 changes from positive to negative, interrupting the flow of anode current in the circuit of electromagnet 113 and relay 108. This electromagnet, by releasing itself, closes the circuit of the upper coil of relay 107 again. The vertical electromagnet 113 raises the brushes 118 — 120 to the predetermined level of contacts by jumping. Further action of the vertical electromagnet 113 causes the interruption of the contacts. circuit of the upper coil of relay 107 on the contacts shown on the left side of this electromagnet, as a result of which relay 107 demagnetizes and releases the connection in case the line circuit is not closed again. During the momentary interruption of the circuit of the upper coil of relay 107, this relay is, however, kept in the active state by the current flowing in the circuit of this coil, which is shunted by resistor 117. This is the momentary inductive current of the coil. Series relay 108 is provided with a conducting tube, marked in the drawing by internal vertical parallel lines, as a result of which, thanks to the eddy currents induced in this tube, this relay is kept in the active state during the subsequent pulses flowing (to During its first operation, relay 108 prepares the circuit for stepping relay 109, which circuit will be closed across non-parent contacts 112, which will occur when electromagnet 113 lifts the switch shaft from its normal position. Relay 109 then operates and closes its own shunt circuit at its upper arm, while at its lower arm it prepares the circuit for rotating electromagnet 114. At the end of the vertical movement of the switch, relay 108 demagnetizes and breaks the initial circuit of the now closed stepping relay 109 and completes the circuit of rotating electromagnet 114, which runs from the grounded tripping cable conductor 105. Electromagnet 114 then operates and — 4 — moves brushes 118-120 until they come into contact with the first group of contacts of the level to which these brushes have been raised. At the end of its stroke, electromagnet 114 interrupts, at the contacts visible on the right side of this electromagnet, the circuit of stepping relay 109, which demagnetizes and at its upper anchor interrupts a further point of its shunt circuit, and at the same time at its lower anchor interrupts the circuit of the rotating electromagnet, which demagnetizes and again switches on relay 109. Further action depends on whether the cable line connected to the first set of series contacts is occupied or free. If this line is free, then it is engaged, as a result of When the relay 110f is occupied, the relay 110 is short-circuited via the grounded triggering cable conductor which is connected to this relay via the test brush 119. The relay 109 operates again in the circuit passing through the test brush 119 and the non-mother contacts 112, and on the grey upper armature it closes its own shunt circuit again, while on the lower armature it closes the circuit of the rotating electromagnet, which is activated and moves the brush to the next group of series contacts. These successive actions of the stepping relay 109 and the electromagnet 114 continue until the brushes reach a free group of series contacts, such as the contacts 128-130. In this case, the switching relay 110 is no longer short-circuited due to the earth connection to its lower terminal, and therefore this relay is excited in a circuit extending from the grounded, tripping cable relay 105 via the non-mother contacts 112 and via the series-connected relay 109, which, however, is not excited due to the relatively high resistance of relay 110. The excited relay 110 interrupts at its upper inner armature a further point of the test circuit and prepares the selector holding circuit; at its lower inner armature, it interrupts the lamp glow circuit and the holding circuit of the upper relay coil 107; finally, at its upper and lower armatures, it disconnects the incoming conductors 104 and 106 from the resistor 123 and from the lower coil of relay 107 and connects them to repeater R1 via series contacts 128 and 130. In repeater R1, line relay 131 is excited via the trigger line and series resistor 139, closing the circuit of trigger relay 132, which then becomes excited and, at its upper internal anchor, applies the earth potential to the corresponding trigger cable conductor running to series contact 129, thereby completing the holding circuit of selector OSI and line switch SL1, passing through the upper internal anchor of switching relay 110. This holding circuit will be closed before the slowly acting trigger relay 107 The station selector OSI has time to demagnetize itself due to the interruption of the circuit of its lower coil on the lower armature of relay 770 and due to the interruption of the circuit of its upper coil on the lower, inner armature of relay 110. The lower inner armature of relay 110 is usually adjusted so that it opens first, in order to extinguish the cathode ray tube 121 and interrupt the flow of anode current, due to the switching off of the lower coil of relay 107 on the lower relay 110, and due to the subsequent change in the grid potential of tube 121 from positive to negative. — 5 — At the moment of extinguishing the cathode ray tube and interrupting the circuit of the upper coil of relay 107, this coil is biased by resistor 117 in the manner already explained, and at the same time by circuit The self-induction current flowing in the upper coil of relay 107 flows through these two shunt circuits, as a result of which the relay releases slowly, keeping the conductor 105 in an earthed condition until the triggering relay 132 of repeater R1 is actuated in the manner already described. After the relay 107 is demagnetized, the relay disconnects the earth connection from the conductor 105* at its upper armature, but the conductor remains connected to earth via brush 119 and the upper, inner armature of the triggering relay 132 of repeater R1*. The demagnetized relay 107 interrupts the further point of the glow circuit and the circuit of its coil at its lower armature. and at the same time prepares the circuit of the tripping solenoid 115, which runs through the non-mother contacts 111, which circuit is interrupted at the lower, inner armature of the switching relay 110. The tripping relay 132 repeats - ka R1, in addition to grounding the tripping cable conductor at its upper inner armature, also closes at its upper armature a bridge situated between the outgoing cable conductors 141 and 142 and passing through the contacts of relays 133 and 134 and through the limit monitoring relay 135. The current now flows in this bridge circuit and on the conductors 141 and 142 in series with the linear circuit of the thousandth selector ThS1 (Fig. 2), which is the same as the station selector OSI (Fig. 1), with the difference that it is located in the switching unit. Since the resistor located in selector ThS1 and similar to resistor 116 in selector OSI limits the current, the limit monitoring relay 135 does not operate at this time. The thousand selector ThS1 is prepared for operation in the manner already described when considering selector OSI. The triggering relay 132 in repeater R1 also closes, at its lower armature, the incandescence circuit of lamp 136, which contains resistor 137. The anode current from a special battery (which may be the battery operating the vertical electromagnet 113 of switch OS1J) cannot flow through relay 133 due to the applied potential negative potential to the grid of lamp 136 from an ordinary central battery FCA via the upper coil of line relay 131 and the developing line running to the grid of this lamp. For this purpose, as already described in the consideration of the OSI selector resistor 116, a large resistor 139 is connected to the circuit of the lower coil of line relay, and the upper coil of line relay 131 is shunted by resistor 143 in order to reduce the inductive resistance of the circuit through which the negative potential is applied to the grid of lamp 121. After the next digit has been dialed, the line circuit is interrupted a corresponding number of times, with each interruption of this circuit the potential of the lamp grid 136 is changed from negative to positive, as a result of which a current pulse flows through repeating relay 133, connected in the anode circuit of the cathode ray tube. After each excitation, relay 133 breaks the bridge between conductors 141 and 142 at its lower armature, sending an impulse to the thousands selector ThS1 (Fig. 2), as a result of which this selector raises its brushes in accordance with the second, selected digit to the desired level of the series contacts and rotates them in search of a free cable line. It is assumed that the cable line running to the hundreds selector HS1 is the line taken into use. A further effect of each excitation of relay 133 is the closing of the circuit of relay 134, which is slowly released by the by a shunt connection of its coil to resistor 120. Relay 134 is excited by the first pulse of the series of pulses and remains in this state during the transmission of the entire series of pulses. Relay 134, when operating, disconnects conductor 141 from the upper conductor of the speaking repeater and from the upper part of the bridge containing relay 135, and connects this conductor to the lower terminal of relay 135 and to the lower speaking conductor, thanks to which inductive relay 135 is disconnected from the impulsing circuit in order to enable a faster increase of the current arising in the linear circuit after each interruption of this circuit. After the calling subscriber A1 has dialed the hundreds digit of the desired number, repeater R1 operates in the manner already described, transmitting pulses corresponding to this digit to selector HS1. This selector begins to operate in the manner described in the consideration of selectors OSI and ThS1 and selects a free cable line, which is, for example, the line containing conductors 231-233 running to switch Cl. After engaging this cable line, its line relay 201 begins to operate, which closes the circuit of triggering relay 203. Relay 203 then applies the earth potential to the triggering cable conductor 232 at its upper armature, interrupts the circuit point of triggering electromagnet 217 at its upper inner armature and applies the earth potential to conductor 234 and closes the lamp incandescence circuit at its lower armature. 211, passing through resistor 212. The flow of anode current through lamp 211 is prevented by applying a negative potential to the grid of this lamp via conductor 233 and the upper coil of relay 201 (shunted by resistor 223) of the cable line coming from repeater RL. After the calling subscriber has dialed the decimal digit of the desired number, the pulses corresponding to this digit are sent via repeater R1 (Fig. 1) to switch G1 via the connection passing through selector ThS1 — HS1. After the first interruption of the line circuit by means of the repeater R1 and the resulting first change of the grid potential of the tube 211 to a positive potential, the special battery excites the vertical electromagnet 218 via a circuit comprising the series relay 204, the non-mother springs 213 and 215, the anode circuit of the cathode ray tube and the lower, grounded armature of the relay 203. In the circuit of the vertical electromagnet 218, the relay 204, which is also connected in series and operates slowly, is also excited, maintaining the vertical electromagnet circuit unchanged after the non-mother springs have moved, which occurs when the switch has made its first vertical stroke. Each pulse following the first pulse is transmitted to the vertical electromagnet via springs 215 and 214 and the lower armature of the energized relay 204. Due to the action of the vertical electromagnet 218, the brushes 220-222 are raised in steps to the predetermined level of the series contacts, whereupon at the end of this vertical movement the relay 204 demagnetizes and switches the anode of the cathode ray tube from the vertical electromagnet to the rotating electromagnet. After the unit digit of the number has been set, the current pulses are transmitted via the tube 211 to the rotating electromagnet 219 and to the slow-acting relay 207 connected in parallel with this electromagnet. Electromagnet 219 rotates brushes 220-222 in increments until they contact the series contacts of telephone line BI. After the first impulse is sent, relay 207 operates in parallel with rotating electromagnet 219, and since it is a reverse-acting relay, it remains active throughout the entire dialing period of that digit. Relay 207, at its upper arm, disconnects test brush 221 from the test coil of switching relay 208 and connects it to occupied relay 206, and at its lower arm, shorts the lower contacts of occupied relay 206, preventing lamp 211 from being extinguished in the event of relay 206 being activated during rotation, which would occur if brush 221 encountered an occupied test contact. The action, which occurs at the end of rotation, depends on whether the withdrawn line is occupied or idle. If this line is occupied, then its test contact has a potential! The earth is supplied through the brush 221, whereby the busy relay 206 starts to operate, closing its own shunt circuit after the relay 207 is released. The said shunt circuit starts at the grounded conductor 234 and runs through the contacts of relays 206 and 207. After the relay 206 is energized and the relay 207 is demagnetized, the lamp 211 goes out, preventing further operation of the rotating electromagnet 219. The relay 206 connects at its lower arm the busy sound conductor 251 to the lower speaker conductor, via a suitable capacitor, whereby the busy sound is sent back via the already made connection with the line The calling subscriber, having heard the busy tone, hangs up the handset again, disconnecting the call. It is now assumed that the BI telephone line is free at the time of the call. In this case, the busy relay 206 does not operate after the brushes 220-221 stop on the contacts of the called line, while the relay 207, after demagnetization, completes the circuit of the test coil of the switching-on relay 208 on its upper arm. This circuit runs from the grounded conductor 234, through the upper arm of the busy relay 206, the upper coil of the relay 208, the brush 221 and through the contact of the relay 207. The above-mentioned circuit of the relay 208 is still connected to the battery and passes through the switching-off relay in the line switchboard (not shown) and through the called-on line. The relay 208, when operating, closes the circuit on its lower internal contacts The shunt coil of its lower coil, containing the triggering cable conductor, at its upper inner anchor applies the ground potential directly to the probing brush 221, at its lower intermediate anchor extinguishes the lamp 211 and at its upper and lower anchors switches on the brushes 220 and 222, as a result of which the bell current flows through the bell conductor 250 to the called line and returns to the battery through the brush 220, the upper speaker conductor and through the upper coil of the relay 205, which switches off the bell. When the called subscriber hears his telephone bell, he then lifts the receiver, causing the direct current bridge to be changed into a bell bridge containing a capacitor, thanks to which the relay 205 starts to operate. This relay closes the shunt circuit of its lower coil on its lower inner armature, while on its upper and lower armatures it breaks the bell circuit, connecting the calling line with the called line. Then the rear bridge relay 202 in the switch starts operating on the called line and on its upper armature it switches off the shunt resistor 223, and on its lower armature it switches on the shunt resistor 209, in order to increase the flow of speaker current in the calling line in the case where the calling line belongs to the same station as the called line, because then a repeater is not needed. In this case, by switching on the shunt resistor 209, the current flowing in the connection between the repeater R1 and the switch Cl is increased sufficiently to activate the edge monitoring relay 135, which, when energized, disconnects the shunt resistor 143 and switches on the resistor 139 associated with the line relay 131, thereby requiring a current flow in the calling line in order to supply a sufficiently large speaking current to the microphone of the calling telephone. The calling subscriber can now talk to the called subscriber (the conversation circuit is marked in the drawing with thick lines). After finishing the conversation, both subscribers hang up their telephones 1', and after the telephone receiver BI is hung up, the rear bridge relay 202 in the switch Cl demagnetizes and reconnects the resistor 209 to the line circuit, as a result of which the edge relay 135 in the repeater R1 demagnetizes and connects the resistor 139 to the calling line circuit. It should be noted that the increase in the line current caused by relays 202 and 135 can be used to start a counter in order to record, if necessary, the charge to be paid by the calling subscriber. In addition, the increase in current at the moment the called subscriber answers and the decrease in this current at the moment this subscriber hangs up can be used for supervisory purposes in the case when the call comes, for example, from a private exchange operated by a telephone operator. After the telephone receiver A1 is hung up, the repeating relay 133 of the repeater R1 starts to operate, breaking the line circuit extended to the switch C1 (fig. 2), and therefore the line relay 131 demagnetizes and breaks the circuit of the slowly acting triggering relay 132. After some time, the relay 132 demagnetizes and at the s-W upper armature breaks the further point of the bridge between conductors 141 and 142, and at its lower armature extinguishes the lamps 136, enabling the passage of The demagnetization of the relays 133 and 134 and its internal anchor removes the grounding fc of the corresponding tripping cable conductor, thanks to which the line switch LSI releases in the usual way and breaks the circuit of the switching relay 110 in the station selector OSI. The demagnetized switching relay 110 closes the circuit of the tripping electromagnet 115 at its lower internal anchor, passing through the contacts of the tripping relay 107 and half through the non-parent contacts 111. This electromagnet then acts and causes the selector OSI to return to its normal position, as a result of which the circuit of this electromagnet is broken at the non-parent contacts 111. After breaking the relay circuit in the repeater R1, By the action of the line switch Cl 201 (Fig. 2), this relay demagnetizes and breaks the circuit of the tripping relay 203, which then disconnects the ground at its upper anchor from the tripping cable conductor 232, allowing the selectors ThS1 and HS1 to be released in the manner already described when considering the station selector OSI. The disconnection of the ground from the tripping conductor 232 allows relays 205 and 208 to demagnetize. Tripping relay 203 closes the circuit of the tripping electromagnet 217 at its upper internal armature, passing halfway through the non-mother contacts 216. Electromagnet 217 operates and, causing switch C1 to return to its normal position, the circuit of the tripping electromagnet is broken at contacts 216. The entire connection is now released and this device can be used to make other connections. The device shown in Fig. 3 will now be described. Instead of using a cathode ray tube in each switch in In the device shown in Fig. 3, as already mentioned, tube repeaters were used, connected in the lines before each first selector, and in all the switching devices operating under the influence of pulses, normal circuit arrangements were used. The repeater R2 according to Fig. 3 differs from the repeater R1 according to Fig. 1 in that after the use of the repeater R2 the grid potential of its lamp 311 is positive, and is changed to negative after each interruption of the calling line. The repeater R2 is furthermore designed so that it operates by simple reversal of the poles of the circuit and not by switching on a high resistance, as is the case in the device according to Figs. 1 and 2. In order to explain in detail the operation of the device shown in Fig. 3, it is assumed that a subscriber of telephone set A2 belonging to one substation wishes to talk to a subscriber of telephone B2 of a distant substation. When subscriber A2 takes off his handset, the line switch LS2 starts to operate in the usual way in order to occupy the free cable line. It is further assumed that this cable line runs to repeater R2 and contains conductors 313-315, and therefore, when this line is occupied on the developing line, the line relay 301, connected in series with resistor 306 and conductors 313 and 315, starts to operate. The line relay 301, when operating, closes the filament circuit of lamp 311, which contains resistor 309. This lamp is ready for operation. It should be noted that resistor 310 is also connected in series with the filament of lamp 311. As indicated in the drawing by the different sized symbols designating resistors 309 and 310, the resistance of resistor 310 is quite small, and resistor 309 — quite large. As a result, the filament of the lamp 311 has a certain average negative potential, close to the potential of the negative terminal of the central battery. On the other hand, the grid of the lamp 311 has a positive potential, very close in its absolute value to the potential of the positive terminal (grounded terminal) of the central battery, thanks to the grounding of the grid by means of a grounded conductor 315 via the telephone line A2, and in the circuit between the grid of the lamp 311 and the negative terminal of the battery, a relatively large resistor 306 is connected in series with the upper coil of the relay 301. By obtaining a suitable positive potential on the grid of the lamp with respect to The filaments of this lamp create conditions that favor the flow of current in the anode circuit of this lamp. It should be noted that a separate anode battery is not necessary, as the upper terminal of anode relay 303 is directly grounded. This device is used because cathode ray tube 311 has such a characteristic that the voltage of the central battery is sufficient to produce the full anode current, activating relay 303. As a result, this relay now operates and, at its lower armature, closes the circuit of relay 302, and at the same time, at its upper armature, breaks the circuit point of the slowly operating relay 304. Relay 302 is excited at its upper inner armature, and prepares the relay circuit 304, at its upper anchor it applies the earth potential to the triggering cable conductor 314 and at its lower anchor it closes an additional lamp glow circuit in order to maintain the glow of this lamp 311 during the pulse in case of demagnetization of relay 301. A further result of the excitation of repeating relay 303 is that the line relay circuit 331 in station selector CS2 closes at its lower anchor, which circuit passes through the upper inductor 312, as a result of which relay 331 operates and prepares station selector 0S2 for operation. When the calling subscriber dials the first digit of the required number, the calling device interrupts the line a suitable number of times, and during each line break the lamp grid potential 311 changes from positive to negative, as a result of which the anode current is interrupted, and therefore relay 303 demagnetizes with each line circuit break, each time breaking the circuit of line relay 331 in station selector 0S2. Relay 303 also breaks the circuit of slow-acting trigger relay 302 with each demagnetization, but nevertheless this relay remains energized due to the shunting of its coil by resistor 307. Furthermore, relay 303 also periodically closes the circuit of slow-acting relay 304, which is energized and remains energized throughout the entire series of pulses because it is shunted to resistor 308. Relay 304 changes the line relay circuit in station selector 0S2, specifically by removing inductive resistance 312 and the upper coil of relay 305 from this circuit in order to improve the impulse circuit. At the end of the digit dialing, relay 303 remains energized, while relay 304 demagnetizes. Station selector OS2, under the influence of the first digit impulses, raises its brushes 333-335 to the desired level of the series contacts, then these brushes are rotated in the usual way in search of a free cable line. After finding this line, e.g., the line running to the thousandth selector ThS2, switching relay 332 operates in the usual way, engaging connecting the cable line and completing the connection with it. Thousands selector ThS2 is the input selector in the remote exchange, and an output repeater is not needed at the output end of the cable line, because repeater R2 is already connected and is therefore ready to repeat pulses. It is not necessary to connect the two exchanges with a triggering cable conductor, because station selector OS2 and line switch selector LS2 are kept in an active state on conductor 314 thanks to the earth potential, supplied via triggering relay 302 of repeater R2. Under the influence of the remaining digits of the preset number, thousands selector ThS2, hundreds selector HS2 and switch C2 begin to operate in in the usual way, in order to make a connection with the telephone line B2. After the telephone subscriber B2 answers, the rear bridge relay (not shown) of switch C2 starts to operate and reverses the connections between the conductors of the incoming line and the line relay of the switch, thereby reversing the direction of current flow in the incoming conductors, which causes a reversal of the direction of current flow in the rear bridge of repeater R2, containing the upper coil - 11 - of polarized relay 305. In this case, the current flows in the same direction through the two coils of relay 305, and therefore this relay operates and shorts resistor 306 at its upper arm, which causes an increase in the intensity of the speaker current. Next, relay 305 disconnects at its lower arm. the shunt of the lower coil of line relay 301, in order to balance the speaking current. The subscribers can now talk to each other, and after finishing the conversation they hang up their receivers. However, after subscriber B2 hangs up the receiver, the current flowing in the line conductors between repeater R2 and switch C2 is reversed, i.e. it flows in the previous direction, after which the polarized relay 305 returns to its normal position. After subscriber A2 hangs up the receiver, repeater relay 303 demagnetizes and breaks the outgoing line circuit at its lower anchor, simultaneously activating relay 304 at its upper anchor. Line relay 301 also demagnetizes, and the tripping relay 302 demagnetizes after a short moment and, at its upper inner armature, breaks the circuit of relay 304, extinguishes the cathode ray tube at its lower armature, and, at its upper armature, disconnects the earth from the tripping cable conductor 314, in order to allow the line switch LS2 and the station selector OS2 to be released. As a result of the interruption of the line circuit at the lower armature of relay 303, the switches ThS2, HS2, and CS of the distant station return to their normal positions. The connection is now completely broken. It should be noted that the repeater R2 is arranged so as to cause the connection to be broken and disconnects from the line. The line, due to poor insulation, may keep the line relay 301 in an energized state, because the repeating relay 303, sensitive to fluctuations in the grid potential of the cathode ray tube, demagnetizes and breaks the circuit of the triggering relay 302 when the calling subscriber hangs up, regardless of whether the line relay 301 has demagnetized or not. After the relay 302 has demagnetized, the line switch releases and releases the repeater, thanks to which the line relay 301 can demagnetize and extinguish the lamp in the event that this extinguishing could not occur automatically due to excessive current leakage in the calling line. The repeater will now be described, shown in Fig. in Fig. 4. When this repeater is engaged in the line switch or in the selector, depending on its arrangement in the cable system, then the line relay 405 is excited in the circuit comprising conductors 401 and 403 and closes the circuit of the slow-acting trigger relay 406, which then gets excited and at its upper anchor brings the earth potential to the trigger cable conductor 403, and at its lower anchor closes the glow circuit of the lamp 411, running from the battery 412, it being noted that each repeater has its own separate battery 412. After the cathode ray tube is lit, the anode current of this lamp flows from the central battery through the lower coil of the relay. line circuit of the automatic switch, to which repeater R3 is connected, via negative cable conductor 422, cathode-anode space of lamp 411, relay 407, positive cable conductor 421, upper coil of linear relay 423 and to ground. At the same time, a branch circuit is created, running from the upper terminal of relay 407, through the contacts of this relay, through the upper coil of polarized relay 409 and to ground through the contacts of relay 410, to which the upper coil of relay 423 is connected in parallel. Relay 409 does not operate in this branch circuit because relay 407 is quickly excited in the main circuit and breaks the branch circuit. Line relay 423 operates in series with relay 407 in a circuit comprising conductors 421 and 422, preparing the appropriate switchboard for operation in the usual way. When a digit is dialed after repeater R3 has been engaged, the incoming line circuit is interrupted a certain number of times, and after each interruption of this line the grid potential of tube 411 is changed, that is, instead of a positive potential applied to the grid along the line, this grid receives a negative potential applied to it through the circuit comprising the upper coil of line relay 405 and resistor 349. The result is that the anode current of tube 411 ceases to flow, which results in the demagnetization of the relay. 407 of the repeater and the line relay 423 in the automatic switchboard, and the relay 407 reconnects the branch circuit containing the upper coil of relay 409. At each closing of the line circuit following a break, relays 407 and 423 operate again, and relay 407 disconnects the branch circuit before relay 408 is energized. At the end of the digit dialing, the grid of the lamp 411 receives a positive potential, and relays 407 and 423 remain energized. After the connection via the automatic switchboard is extended to the called line and after the called subscriber has answered, the connection between the line relay is reestablished in the usual way, which now supplies current to the rear bridge. in the repeater and the linear conductors reaching this linear relay, as a result of which the direction of current flow in the rear bridge of the repeater tends to reverse. Since the direction of current flow through tube 411 cannot be reversed, relay 407 demagnetizes and cannot operate again, whereby a negative potential is applied via upper conductor 421 and the contacts of relay 407 to the upper coil of polarized relay 409, which circuit is connected to ground via the contacts of relay 410. Relay 409 now operates and completes the circuit of parallel relays 404 and 410, of which relay 404 reverses the connection between linear relay 405 and input conductors 401 and 403, and simultaneously turns off resistor 349 and disconnects the shunt from the upper coil of relay 405. The input linear circuit is thus balanced, so that the speaker current is not subject to major side fluctuations. Moreover, the current is increased in intensity to sufficiently power the calling line microphone, and the direction of the current in the calling line is reversed. It can therefore be seen that repeater R3 provides both high-resistance supervision and supervision consisting in reversing the direction of the current. Each of these supervisions can be used separately or in combination. Relay 410, when operating, closes its own shunt circuit at its lower internal armature, running to the grounded triggering cable conductor 402, simultaneously breaking its initial circuit, moreover, at its intermediate lower anchor it extinguishes the lamp 411 and at its lower anchor it completes a new bridge between the conductors 421, 422, passing through the inductive coil 413 and the lower contacts of the line relay 406. When the calling subscriber hangs up the receiver after finishing the conversation, the direction of the current flowing in the conductors 421 and 422 is reversed to the normal direction, as a result of which the current flows in the reverse direction through the inductive resistor 413 and the upper coil of the relay 409, and therefore the relay 409 returns to its normal position, but the relay 410 continues to maintain its shunt circuit. Relay 404 returns to its normal position and reverses the direction of current flow in conductors 401 and 403, that is, the currents in these conductors now flow in the original normal direction, with the result that the incoming line returns to the condition it was in before the call was answered. It should be noted that lamp 411 has no effect on the operation of the handset during the call answering process, because relay 410 extinguishes this lamp, maintaining it in this state until the call is interrupted. After the calling telephone receiver is hung up and the current flow in conductors 401 and 403 is interrupted, line relay 405 demagnetizes and breaks the circuit of the slow-acting relay. Relay 406 also demagnetizes itself and, at its lower armature, breaks the bridge between conductors 421 and 422 to allow the connection made by subsequent automatic switches to be broken, and at its upper armature, disconnects the ground from the tripping cable conductor 402 to disconnect the repeater from the automatic switch that previously occupied it. Some of the operating features of several circuits shown in the drawings will now be described in more detail. With reference to Fig. 1, it should be noted that the lower coil of relay 107 is connected between the negative pole of the central battery and the grid of lamp 121, so that when the calling telephone When a break occurs, the lower relay coil 107 tries to maintain the current flow thanks to its self-induction, which causes the grid of the lamp 121 to obtain a momentary positive potential, therefore greater than the ground potential. This causes a rapid increase in the anode current of this cathode-ray tube. On the other hand, when after the break, the linear circuit closes due to the inductance of the lower relay coil 107, a moment occurs when no current flows through the lower relay coil, and the potential of the grid 121 becomes equal to the potential of the central battery, connected to the grid via resistor 123 and the developing line conductors. The result of this phenomenon is a rapid reduction in the anode current of the lamp, and therefore a rapid termination of the pulse. The same conditions apply to repeater R1, to which a resistor 143 is added, connected in shunt to the upper coil of relay 131, which makes the linear circuit practically inductive. The exception is the lower coil of linear relay 131, connected between the lamp grid and ground. A similar device is used in switch Cl. In repeater R2 (Fig. 3) the lower coil of relay 301 is normally connected in shunt in order to eliminate the induction of this coil from the pulse circuit, while the upper inductive coil 301 is connected between the negative pole of the central battery and the grid of the lamp 311. This is to increase the inductance of the interrupted circuit by adding to this inductance the self-induction of the upper inductive coil 301. This increases the amplitude of the current fluctuations caused by line interruptions, which in turn causes stronger potential fluctuations on the grid of the lamp. Thanks to this device, the grid of tube 311 has a greater negative potential when the line is interrupted than at the moment of interruption, while the grid becomes more positive at the moment of closing the linear circuit after its interruption than at the moment after the circuit is closed, resulting in the desired, rapid changes in the anode current flow. The same device is used in repeater R3 according to Fig. 4. It should be noted that in all these cases, after the called subscriber answers, the linear circuit is balanced and the speaking current increases, because there is then no need to continue to maintain the conditions necessary for dialing the number. PL PL PL PL PL PL PL PL PL PL PL PL PL

Claims (1)

1.