Patent GB-409356-A (GB)
Title: Arrangements relating to automatic telephone systems
IPC: H04Q3/00
Filed: 1932-10-28
Abstract: 409,356. Automatic exchange systems. OLSON, A. H., and VIGRBN, S. D., 2, Brunkebergstorg, Stockholm, Oct. 28, 1932, No. 30334. [Class 40 (iv).] In a network comprising a number of small terminal offices A, a central office D22 and intermediate offices K, the terminal offices use the code translating register controllers of the intermediate offices and local calls at any office are made without the use of register controllers. As shown, a subscriber 12 of the terminal office A10 on calling gets access via a call finder S10 and direction switch RV10 to a final selector LV10 which he sets in known manner to establish a local call. Outgoing calls are established by dialling a special digit whereupon the direction switch seizes a two-way junction and releases the local switches. A register controller R18 at the office K18 is then associated with the junction, receives the office and name digits of the wanted number and controls the establishment of the connection in known manner. Outgoing calls are set up by dialling the special digit into the final selector (e.g. LV18), whereupon the direction switch RV18 seizes an outgoing selector SGV18 and a register controller R18. Certain terminal offices, e.g. A14 have direct junctions incoming from distant intermediate offices in addition to the normal two-way junctions to the nearby office. In a modified system, the direction switches at the larger offices are omitted, a single stage of incoming local group selectors being provided. These in response to local digits select final selectors and in response to the special outgoing digit cause the selection of a register controller, release themselves and are set again by the register controller to select a junction. The circuits of bar-relay group selectors for this purpose are shown in detail. Local call in intermediate or central office. When the finder on line L, Fig. 3, switches through, R10, Fig. 4, energizes R11, R12 to operate the cut-off relay and send back dialling tone from SO with the aid of a 3rd winding on the line relay. Stm0 is energized by the first impulse, energizes R13 (which locks) and locks at the end of the impulse in series with R14. The 2nd impulse energizes Stm1 which releases StmO. At the end of the impulse R14 falls. Similarly the 3rd impulse energizes Stm2 and R14 and releases Stm1 and so on. At the end of the digit R12 falls and energizes brm1 to close the contacts 1, 2, 3 of the operated Stm relay and so associate the circuit with the 1st trunk in the wanted group. If this is idle, test relay R9 is operated, but if not brm2 is operated to close the contacts 4-6 belonging to the 2nd trunk and release brm1 and so on. R9 on operating energizes R8 to switch the talking circuit through to the final selector and release R14, R10, R11, R13. R11 releases R9, but R8 is held over the outgoing c wire. Outgoing calls in intermediate or central office. The subscriber dials O which produces a single impulse. As a result, R12 falls with StmO and R14 energizes STM1, Fig. 3. STM1 energizes HBRM1 which connects the test relay R7 to contact 2 (R5) in the first register controller. If this is idle, R7 pulls up, but if not, HBRM2 is energized and connects R7 to the next registercontroller and so on. If all the registercontrollers are busy the cycle is repeated. R7 on energizing energizes R6 which locks and energizes the magnet BRM corresponding to the operated relay HBRM. This magnet co-operates with STM1 to seize the registercontroller in which R4, R5 pull up releasing R7, whereupon R1 pulls up and the incoming and outgoing a and b wires are extended over separate circuits to the register-controller. In the group selector, Fig. 4, R10 and the other operated relays are released. The subscriber now dials the exchange and subscriber numbers into the register-controller. At a suitable stage R3 loops the a and b wires going to the selector and R10, R11, R12 pull up. The selector is then controlled by the register-controller in the same way as by the dial in local calls. Calls incoming from terminal offices. The incoming selectors are the same as the 1st selector shown except that - battery is permanently connected to contact 1 (R11) and contact 1 (R13) is connected to wire d. As a result a register controller is seized at once.