Patent GB-131583-A (GB)
IPC: H04M5/08
Abstract: 131,583. Arntzenius, C. R. H. Aug. 19, 1918, [Convention date]. Manual and semi-automatic exchange systems. -Relates to systems in which calls are extended from a manual exchange, Fig. 1, through an intermediate exchange, Fig. 2, either automatically or with the help of an operator, to a third exchange. The trunk a, b, leading from the first to the intermediate exchange, is provided at the latter exchange with a set of relays 105, 106, 107, 108 selectively responsive to currents of different strength and polarity applied to the wires a, b by the depression of keys 1, 19, 19' at the first exchange. The depression of the key 1 applies positive current to both wires a, b, the relays 105 - - 108 then operating to connect the trunk a, b to an operator 101, Fig. 2, who extends the call by inserting plug 102 into a jack 103 leading to the third exchange, shown in Fig. 3. The depression of the key 19 applies positive current to wire a and negative to wire b, the relays 105 - - 108 then operating to connect the trunk a, b directly to a trunk 300 leading to the third exchange shown in Fig. 4. The operator 101, plug 102, and trunk 300 at the intermediate ex. change are accessible also to other incoming trunks similar to trunk a, b, and connexion is only made to the operator &c. when idle. Supervisory signalling arrangements are described in detail. The trunk a, b terminates at the first exchange, Fig. 1, in a pair of plugs 3, 4, either of which can be connected to the trunk by the operation of the keys 3', 4'. At the intermediate exchange, the trunk a, b is connected to the selective relay set, shown to the left of and below the trunk, comprising two polarized relays 105, 106 and two unpolarized relays 107, 108, of which the relays 105, 107 are connected between wire a and earth, while relays 106, 108 are connected between wire b and earth. Operation when trunk a, b is connected to idle operator 101, Fig. 2, at intermediate exchange, who extends call by inserting plug 102 in jack 103 to desired third exchange. To call the operator at the intermediate exchange, the operator at the first exchange depresses key 1 thereby connecting positive battery to both wires a, b, and energizing all four relays 105, 106, 107, 108. Each of these relays energizes two other relays, viz. 112, 149; 110, 137; 113, 136; and 111, 138. A circuit is then closed over the contacts of relays 110, 111, 113, 112 in series for relay 114 and relays 115, 116, 117 in parallel, these relays 114 - - 117 operating to connect the trunk a, b to the operator 101 and plug 102. If the plug 102 has not been taken into use by some other trunk, the relay 119 is energized over resistance 118 and contacts of relay 117. If, however, the plug is in use, relay 119 is not energized and a busy signal is connected over its back contacts to the calling operator. Assuming that the plug is free, relay 119 short-circuits its upper winding to mark the plug busy, and closes a circuit through relay 122 and a locking-winding of relay 115. If the operator 101 is free, relay 121 is energized over resistance 120 and extends the operator's circuit 101 over the armatures of relays 121, 119, 116, 115 to the calling trunk a, b. If the operator 101 is engaged, relay 121 is not energized and transmits a busy signal over its back contacts to the calling operator. When the calling operator has communicated with the operator 101, she releases the key 1 so that relays 105 - - 108, 110 - - 113, 114, 116, 117, 119, and 121 de-energize but relay 115 remains energized over its locking-winding in series with relay 102. The trunk a, b is thereby connected through to the plug 102. On the release of the key 1, relay 7 de-energizes and connects negative battery over plug switch 22, relay 13, and resistances 8, 9 to the trunk wires a, b, thereby energizing relays 107, 108 but not relays 13, 105, 106. The insertion of plug 102 in jack 103 completes a circuit through the sleeve relay 124, Fig. 2, socket of jacket 103, middle point of impedance 125, over both sides of the trunk to the third exchange, and relays 205, 206 to earth. Relays 124, 206 energize, but not relay 205 owing to its high resistance. Relay 124 closes a circuit over relay 132 (which disconnects lamp 104) and relay 133, which earths both trunk wires a, b, over resistances 134, 135, thereby energizing the relay 13, Fig. 1, which lights supervisory lamp 2. If the operator 201 is free, relay 206 energizes relay 207, thus connecting her to the incoming trunk. If the operator 201 is busy, relay 207 is not energized and connects a busy tone to the calling trunk. Upon learning the connexion desired, the operator inserts plug 202 in the jack of the wanted line, thereby energising the sleeve relay 226, which causes relay 209 to disconnect relay 206 and the operator's circuit 201. The disconnexion of relay 206 (1) energizes relay 205 which opens the circuit of the clearing-lamp 203 and (2) decreases the current over the trunk circuit to the intermediate exchange so that relay 124 opens the circuit of relays 132, 133, and therefore of relay 13 controlling lamp 2. The operator at) the first exchange then calls the wanted subscriber by depressing her ringing-key 10, which connects current of frequency 16 to the relay 11, which in turn causes relay 12 to connect current of frequency 133 to the trunk leading to the intermediate exchange, wherein, by means of condensers, resistances 126, 127, and relays 128, 129, 130, 131, this causes a current of frequency 16 to be supplied to the trunk leading to the third exchange and thence to the desired line. A relay 211, Fig. 3, is energized by this ringing-current, but does not lock up in series with a relay 210 under control of relay 205, since the circuit of relay 205 is at this moment opened by the ringing-relay 128, Fig. 2. After conversation, the called subscriber rings off, thereby energizing relay 211, and since the relay 205 is now energized, the relay 211 locks up in series with relay 210, which connects a relay 212 in parallel with relay 205, thereby increasing the current over the trunk to the intermediate exchange so as to energize relay 124, which as before causes the energization of relays 132, 133, 13, so that the clearing lamp 2 again lights up. When the calling party hangs up, the cord relay 14 or 15 is energized, closing a circuit for clearing lamp 5 or 6 and also relay 17, which lights the guard lamp 16. Thus the supervision of the call is under the control of the first operator. When she removes plug 3 or 4, the plug switch 22 disconnects battery from the trunk wires a, b so that relays 105 - - 108 are all without current. Relay 147 is thereby energized, and opens the holding-circuit of relays 122, 115, which de-energize and open the circuit of relay 132, thus lighting the lamp 104. The operator at the intermediate exchange then removes the plug 102 from jack 103. If the operator at the first exchange wishes to set up a further connexion, instead of withdrawing the plug 3 or 4 she depresses key 1, say, thereby energizing relay 114, say, which causes the energization of a relay 148, which opens the holding-circuit of relays 115, 122, whereby relay 132 closes the circuit of lamp 104 as before. Operation when trunk a, b is connected through intermediate exchange to third exchange without the help of an operator at the intermediate exchange. To extend a call to the third exchange shown in Fig. 4, the operator at the first exchange depresses key 19, thereby connecting positive battery to the wire a and negative to wire b. This results in the energization of relays 105, 107, 108 (but not relay 106) which in turn energize relays 112, 149; 113, 136; 111, 138. A circuit is thus closed over the contacts of relays 112, 136, 138 in series for relay 139 and relays 140, 141, 142 in parallel, these relays 139 - - 142 operating to extend the trunk a, b direct to the trunk 300, if the latter is free, in the same way as relays 114 - - 117 extend the trunk to the plug 102. If the trunk 300 is in use, a busy signal is sent over the back contacts of relay 144 and front contacts of relays 140, 141 to the calling operator. If the trunk is free, relay 144 is energized and closes a circuit through relay 145 and the holding-winding of relay 140, so that this relay remains energized when the key 19 is released. A circuit is also closed over the middle point of resistance 146, both sides of the trunk to the third exchange, for relay 217, Fig. 4, which, if the operator 213 is free, energizes relay 218 to extend the call to this operator. After learning the connexion required, the operator 213 depresses the test key 225 prior to testing the desired line. If this is free, she releases key 225 and inserts the plug 214, thereby energizing relays 224, 221, 222, and 223. The substitution of relay 223 for relay 217 increases the current over the trunk to the intermediate exchange, thereby energizing relay 133, Fig. 2, which as previously described energizes relay 13 at the first exchange and lights lamp 2. The first operator then rings up the wanted subscriber, as previously described, and when the subscriber replies, the relays 221, 222, 223, 133 and 13 successively de-energize, thereby extinguishing lamp 2. When the called subscriber replaces his receiver, relays 221, 222, 223, 133 and 13 again energize, lighting lamp 2. When the calling subscriber hangs up, lamps 16 and either 5 cr 6 light up as previously described. The withdrawal of the plug 3 or 4 disconnects battery from the trunk wires a, b, whereby relays 105 - - 108 are all de-energized and close the circuit of relay 147, which opens the holding- circuit of relays 145, 140. Relay 140 opens the simplex circuit over the junction to the third exchange, whereupon relay 223 de-energizes and lights the clearing-lamp 215.