Patent GB-174035-A (GB)
Abstract: 174,035. Automatic Telephone Manufacturing Co., Ltd., (Assignees of Ray, A. J., Madsen, F. T., and Obergfell, H. F.). Jan. 11, 1921, [Convention date]. Automatic exchange systems; party line systems.-A connector for use in a small exchange is adapted to make connection with an ordinary line, with a party line, with an idle trunk to a manual exchange, or with an idle trunk to an automatic exchange. For this purpose the connector H, Fig. 1, has associated with it four auxiliary switches I, J, K, L, Fig. 2, and a code-ringing controller M. The switch J acts like a sideswitch to control the effect of the successive digits which reach the connector. The switches K, I, which are only operated when the call is to a party-line are set in such case by the third and fourth digits and co-operate with the ringing controller M to pick out a corresponding code signal, for example if the third and fourth digits are 31 the signal will be three rings, a pause, and a single ring. Under control of the switch L this signal is transmitted to the called party line once for every rotation of the controller M until the wanted subscriber answers, the switch L performing a cycle of operations for every repetition of the signal. Call to an ordinary line 172, 174, Fig. 6. When a call is extended by a line switch C to the connector H the line and release relays 52, 53 are energized in the ordinary way. The first digit is repeated to the series relay 54 and vertical magnet 126 over wire 186 and the wiper 267 of the switch J in its first position. The relay 54 energizes relay 59 in a circuit 83, 113, 86. and at the termination of the digit. in the interval between the relapse of relays 54, 59, an impulse is transmitted over a circuit 83, 113, 86, 116, 102, 94, 184 to the magnet 252, which steps the switch J 'to its second position, disconnecting the vertical magnet 126 and preparing the circuit 185 of the rotary magnet 127. The second digit operates the rotary magnet, and at its termination an impulse is again sent over the circuit 184 to move the switch J to its third position. In the interval between the relapse of relays 54, 59 the test relay 57 is conected in a circuit 98, 117, 85, 66, 180, wiper 266 of switch I in the first position, wire 196 to test wiper 137. If the wanted line is busy, relay 57 becomes energized, locks itself up, and connects busy tone to the calling line, but if the wanted line is idle the de-energization of relay 59 a moment later completes a circuit from the test wiper 137 through wires 196, 180 and contacts 66, 85, 117 to relay 56, which becomes energized in series with the cut-off relay 14', Fig. 6. Relay 56 locks itself, grounds the test wiper 137, opens the operating circuit of the switches I, K, and connects the ringing generator V, Fig. 2, to the wiper 138 in a circuit including the wiper 270 of the switch K in its first position, wire 182, contacts 91, 100, 69, this circuit being completed at regular intervals by the energization of relay 101 over the contacts engaged by the wiper 281 of the ringing-controller M. From the wiper 135 the ringing circuit is completed through contacts 65, 87, 109, the lower winding of the ringing cutoff relay 55, contact 94, wire 184, and magnet 252, which does not respond. On the reply of the called subscriber the relay 55 responds, locks itself, and completes the talking circuit, the called line being fed through the usual backbridge relay 51. When the calling subscriber disconnects himself the release magnet 128 is energized in the usual way and grounds the circuit 198 of the release magnet 259 of the switch J. A parallel circuit for the magnet 128 is provided through the wiper 268 to keep the circuit 198 grounded until the switch J is fully restored. The release magnets of the switches I, K are energized in parallel with the magnet 128, but in the present instance these switches have not been moved from normal. Call to a party-line, 175, 177, Fig. 5. The test wire 173 of a party line is connected to the bank of wiper 136, the corresponding terminal in the bank of wiper 137 being dead, so that the idle or busy condition of the line is not tested at the termination of the second digit and the relay 56 is not energized. The third and fourth digits, representing the party-line code number of the wanted subscriber, are repeated over wire 187 to the magnets 254, 251 of the switches K, I, these magnets being put in circuit by the wiper 267 in the third and fourth positions of the switch J. At the termination of the fourth digit, the switch J moves to its fifth position, and in the interval between the relapse of relays 54, 59 the test relay 57 is connected in a circuit 98, 117, 85, 66, 180, wiper 266 of switch I in an off-normal position, wire 191, to test wiper 136. Assuming that the wanted line is idle, the relay 57 does not become energized, and the relapse of relay 59, a moment later, energizes the relays 56, 14<2> in series over the wires 180, 191 and the test wiper 136. Relay 56 locks :tself, grounds the test wiper 136, prepares the ringing circuit, and connects a tone machine T<1> over wires 199, 197, 182 to the called line, so that any subscriber on the party line who may at this lime lift his receiver to initiate a call will hear the tone and be warned off. (It will be seen from Fig. 5 that the switch-hooks of party line subscribers are provided with stops 288<1>, so that a subscriber who lifts his receiver without freeing the stop does not metallically bridge the line but merely connects his receiver across it in series with a condenser, to enable him to hear the tone.) Code ringing now proceeds under control of the switches K, I, L and the controller M. The controller is a rotating cylinder bearing a number of contacts which engage with wipers 275 ... 281, the contacts being grounded by a spring 297<1> which is arranged to break connection a moment before the wipers 275 &c., so as to prevent sparking at the wipers. It will be seen that each of the switches K I picks out one of the wipers 275 .. 279. The moments at which ringing can take place are those when the wiper 280 is on one of its contacts, these contacts being aranged in two series of five separated by a space. The wiper picked out by the switch K determines which shall be the first effective ringing moment in the first series, and the wiper picked out by the switch I determines which shall be the last effective ringing moment in the second series. Thus if the third and fourth digits are 31, the switch K will pick out the wiper 277, which will start the ringing cycle when it reaches the contact 285, and the switch I will pick out the wiper 276, which will terminate the ringing cycle when it reaches the contact 297. Thus in this case four rings will be given when the wiper 280 engages the contacts 290, 291, 292, 293, the first three rings being separated from the fourth by a pause. When the wiper 277 engages the contact 285 it closes a circuit 269, 181, 193, 272, 253, 267 to energize the 'magnet 253, which moves the switch L to its second position, closing a circuit 83, 194, 271, 190 to energize relay 58, which prepares the circuit 189 of the ringing relay 60, which is thereafter energized whenever the wiper 280 engages a contact 290, 291, &c. The relay 60 connects the generator V<1> to the connector wiper 138 in a circuit 197, 270, 182, the ringing circuit being completed from the wiper 135 through contacts 65, 87, 109, 95, 78. When the wiper 279 of the controller M engages the contact 294 the switch L is moved to its third position, and when the wiper 276 engages the contact 297 it completes a circuit 265, 272, 253, 267 to move the switch L to its fourth position, whereby the relay 58 is de-energized to prevent further ringing while the controller M completes its cycle. When the wiper 279 engages the contact 298 the switch L is moved to its fifth position, in which it closes a circuit 83, 194, 271, 193 to energize relay 59, which closes the circuit 192 of the release magnet 260 to restore the switch L to normal, and the apparatus is ready to repeat the code signal during the next rotation of the controller M. It will be seen that the relay 58 which is energized throughout the duration of each code signal, opens the circuits of the ring- ing cut-off relay 55 and of the release magnet 128, so as to prevent a mutilated signal from being sent to line in case the called subscriber answers or the calling subscriber disconnects himself in the middle of a code signal, but when the called subscriber answers, the next de-energization of relay 58 is followed by the energization of relay 55, which locks itself and completes the talking circuit as before described. Call to a manual-exchange trunk line 168, 169, Fig. 4. The manual exchange is called by the digits 91, which bring the connector to the terminals of the first trunk. The test terminals of these trunks in the banks of the wipers 136, 137 are strapped together, except those of the last trunk, so that if the first trunk is busy the test relay 57 is energized in the interval between the relapse of relays 54, 59, in a circuit 98, 117, 85, 66, 180, 266, 196, 137, and completes a circuit from wiper 136 through a contact 124, which is closed when the connector is on its ninth or tenth level, to energize relay 60. Relay 60 locks relay 59 and co-operates with the rotary magnet 127 in known manner to hunt the connector over its ninth level. When the connector finds an idle trunk relays 57, 59, 60 relapse and relay 56 is energized over wiper 137 and resistance R<1>. Relay 56 locks itself, grounds the test wiper 137, and causes the application of ringing current across the wipers 135, 138, thereby energizing a self-locking alternating-current relay 300 at the manual exchange to light a call lamp 302. When the operator answers the call the ringing cut-off relay 55 is energized and completes the talking circuit. Since an exchange conn