Patent GB-197503-A (GB)
Title: Improvements in or relating to the transmission of telephone numbers or the like
IPC: H04M7/08
Filed: 1922-04-12
Abstract: 197,503. Automatic Telephone Manufacturing Co., Ltd., and Harrison, H. H. April 12, 1922. Order apparatus. - Telephone numbers are transmitted between distant exchanges by code impulses over a line which may normally be used for telegraphy. At the distant exchange, the impulses operate special storing mechanism to give a visible indication, as described in Specification 163,807, or to operate switches to establish the connection. In the arrangement described, signals similar to those of the five-unit code but comprising only four units are sent over a simplex circuit superimposed on a telephone line L1, L2 between the exchanges A, B. Ten digital keys KL selectively control bars 1-4 which connect positive potential to contacts 1-1 of a rotary distributor C, .which is set into operation by the energization of a latch magnet LM1 bv the bar 5 upon depression of any key. Positive potential on contact 7 is connected to line over the arm BA1 and unbalances a polarized relay LR at the distant exchange, energizing the latch magnet LM2 of a similar rotary distributor D, which then moves in synchronism with the distributor C. A stepping magnet RM1 is operated over contact 7 to move a switch DS one step, energizing a multi-contact relay MCR which connects ten wires from storage relays SR 1-4 to digit storage relays DSR. The storage relays are connected to contacts 1-1 of the switch D and are selectively energized upon unbalancing of the relay LR by positive potential on contacts 1-4 of the switch C, causing the corresponding one of the digit storage relays DSR to be energized over contact 5 and the arms BA3 of the switch D, connecting earth to one of the contacts of the wiper C1 of an impulse sender. The key KL is held depressed by a latch LB controlled by a release magnet RM which becomes energized when the arm BA2 reaches contacts 9, 10, whereupon the key is released, stopping the rotation of the switch C so that the arm BA1 comes to rest on a contact 6. A cut-off relay COR is energized over contact 6 of the switch D and releases the storage relays SR 1-4, and the switch D comes to rest on contact 7. The remaining digits are set up on other sets of digit storage relays in a similar manner, the relays corresponding to the last digit being provided with additional contacts, so that earth is connected to a lead 20 to operate a starting relay SR5, which energizes a magnet SM, releasing the wipers A1, B1, C1, D1 of an impulse sender for one revolution. Each step of the wiper A1 causes an impulse to be sent over a lead IW, until the wiper C1 reaches the contact earthed by the first set of digit storage relays, energizing a relay R which disconnects earth from the contacts of the wiper A1. The digit storage relay is restored by a relay COR1 energized over the wiper D1 in series with the relay R. The sender has four banks of contacts corresponding to the four digits, the action being similar for each digit, and the restoring relay COR4 corresponding to the last digit finally opencircuiting the magnet SM to stop the rotation at the end of the revolution.