Patent GB-292331-A (GB)
Title: Improvements relating to telephone systems
IPC: H04Q3/42
Filed: 1927-05-19
Abstract: 292,331. Siemens Bros. & Co., Ltd., and Christian, D. A. May 19, 1927. Semi-automatic exchange systems. - An A- operator at a manual office controls a pre-selected register-sender at an automatic office over an order wire over which, in the system described, the number of the junction with which the sender is associated is signalled as soon as she has set up the wanted number. She then plugs in and releases the order wire for common use. If she fails to plug in, the sender stops before sending the final digit and, after a time interval, releases itself and the partly established connection. The key strip KS, Fig. 1, controls relays A - - F, Fig. 2, at the outgoing end of the order wire to connect + or - to the wire 12 and to one or both of the wires 11, 13. The code signals are received by three pairs of oppositely polarized shunt-field relays SA - - SF which are connected star-fashion to the wires 11 - - 13 and transfer their records to storage relays in the sender. A similar group of relays DA - - DF at the outgoing end responds to the code denoting the junction number and controls storage relays in a number indicator. Specification 265,732 is referred to. Non-numerical switching arrangements. In the system described the idle register-senders are kept associated with idle junctions by twomotion switches JA - - JC, Fig. 5 which hunt in succession over all their levels but these switches may be modified (a) so that rotary release takes place on the first terminals of busy levels (b) to skip busy levels (c) so that part of the bank is barred electrically or by mechanical stops. Where there are more than 100 junctions, multi-wiper simultaneous hunting switches may be used. When the switch returns to its normal position, relay DJ energizes the vertical magnet VM. Vertical springs k<2> release DJ which shortly afterwards energizes RJ which locks up and re-energizes DJ to make a selfinterrupting circuit for rotary magnet RM. At the end of the level, test relay TJ pulls up in series with relay LJ which is connected to 11th terminals on the first 9 levels. Relay LJ holds itself and DJ and releases RJ which releases TJ to operate the rotary release magnet RZM. Rotary springs w' on restoring release LJ which energizes the vertical magnet and releases DJ which shortly afterwards releases the magnet and energizes RJ to initiate the testing of the new level. If the switch is unsuccessful on the 10th level, TJ pulls up in series with EJ which energizes release magnet RM, and the switch begins again at the bottom. When an idle junction is found TJ pulls up in series with N, Fig. 6, and marks the junction busy. While the switch is hunting or the register sender is off-normal, ground is connected over 23, E to the corresponding terminal in the bank FE of the hunting switch FA - - FF in 'which the order wire terminates. The switch is thus kept moving until it reaches an idle sender which is associated with a junction. Appropriating order wire. When the operator presses the key OW, E connects up T, which if the order wire is idle, cuts off E and locks up over a low resistance winding in series with TS and connects H to the wire A. TS busies the order wire and reverses the current in the right hand winding of T to make it quick to release. Provided the switch FA - - FF is not hunting (in which case FT would be energized) H and FR pull up in series, the register sender is busied and its relay CR operated and the relay B, Fig. 1 is released to cut off the busy tone BT. If the order wire is busy, relays F, G pull up in succession after E, and G disconnects T and E whereupon E - - G fall back sluggishly in succession. By this means T is connected up for a short time at comparatively long intervals governed by the release times E - - G and since these times will generally differ for different operators, the chance of double seizure is small. Code transmission and registration of wanted number. Each key of the strip KS operates 1 or 2 of the code-sending relays A - - F in series with a relay PS which connects up the wires 11 - - 13. The code receiving relays SA - - SF energize one or more of the storage relays MA - - MD &c. in series with a relay P which energizes the back stroke magnet CM of the controller AC - - FC. The storage relays remain locked when the key is released, but relay P allows the controller to move its wipers to connect up the next storage group. Code transmission and display of junction number. From 5 - - 9 the controller moves automatically under the joint control of its contacts cm and the relay N. In 5 it energizes CO which disconnects the receiving relays and connects the wires 11 - - 13 to wipers AC - - CC. In 6 the wires 11 - - 13 are extended to the contacts of code sending relays LA - - LF which are operated in accordance with the position of the vertical wiper JV on the hunting switch. In 7 and 8 the relay COJ is operated and gives control of the code sending relays to the rotary wipers JD, so that when the wires 11 - - 13 which are disconnected in 7 are connected up again in 8, the units digit is transmitted. At the manual office, code receiving relays DA - - DF operate the tens relays TA - - TD in series with relay P which energizes Q to cause the relapse of P to energize C to connect up the units relays UA - - UD. Decimal transmission of wanted number. Relay ST which pulls up when the first digit has been registered connects the sending switch magnet SM to interrupter I<2>. Wiper AS on its 9th terminal energizes pick up relay S which removes a short-circuit from springs I<1> which are connected to the junction impulse relay A. When the wiper reaches the terminal marked by the thousands relays, stop-relay F releases relay S, locks up over the homing wiper and sends the switch home. In this position, relay DD pulls up before relay F has time to fall back to start a new cycle and as a result the first sequencerelay AD pulls up when wiper AS reaches its 4th terminal and substitutes the hundreds for the thousands marking. The remaining digits are sent in a similar manner. If at any stage the switch is ready to send a digit which has not yet been recorded, relay SP the windings 3, 2. 1 of which are connected in succession by the sequence-relays to the 2nd, 3rd and 4th terminals in the controller bank FC, holds the sending switch until the digit has been recorded. Completion of connection and release of register sender. When the final digit has been sent, relay F releases relay ST to release the storing and sequence relays and the controller is stepped under control of its springs cm and relay N. Relay ST also releases relay N, Fig. 6, to complete the talking circuit and relay TJ which releases A, J and CR the latter causing the controller to race home. Forced release. From 9 on, the relay N which controls the controller magnet receives impulses from a 1 second interrupter I<3>. If the operator fails to plug in, and so operate relays L, J. relay SP, which stops the sending switch when sending overtakes recording, pulls up to prevent transmission of the final digit. The controller on reaching its 25th terminals (if J is still unoperated) short-circuits ST and release takes place as before. According to the Provisional Specification the operator may be connected to an idle order wire by a hunting switch and the keyboard may control the transmission of decimal impulses or may transmit codes of the kind described in Specification 265,732.