Patent GB-496063-A (GB)
Title: Improvements in or relating to electrical signalling systems
IPC: H04L12/18
Filed: 1937-06-03
Abstract: 496,063. Electric signalling systems. ERICSSON TELEPHONES, Ltd., and LIMB, F. June 3, 1937, No. 15374. [Class 40 (i)] Stock and like quotations are transmitted to a calling party from a common set of voice records of the necessary words, adapted to transmit simultaneously words forming parts of the same or different quotations to different calling parties. In the system shown, a calling party obtains access over a line finder and group selector, as in automatic telephone exchange systems, to a final selector FS having a number of wiper sets dependent on the number of words in the quotation, and contacts which are connected to the wipers of price switches FA-FC which may be set by manually controlled dials as shown in Fig. 3, or by known control arrangements. The contacts of the price switches are connected to reproducers of the various word records. On initiation of a call, line relay LR pulls up and closes a start circuit through assigner AS which causes an idle finder LF to hunt for the calling line and extend the line to a group selector GS which grounds the third wire to operate CO in series with the left-hand winding of LR the line winding of which is thereby disconnected. The line is extended to a final selector in known manner and line relay A thereat pulls up followed by B and C, the filament circuit of valve SV being completed by B. Relay A repeats the next impulse train to vertical magnet B in series with C which holds although its original operating winding has been short-circuited at off-normal contacts n. At the end of the train, C relapses, change-over relay E pulls up and C re-operates so that the next impulse train is repeated to rotary magnet R and relay C in series. The final selector is thereby stepped to contacts connected to wipers FA-FC of the price switches of the desired stock. Relay C releases at the end of the impulse train and relay TR pulls up over wiper fs7 unless the price switches are being re-set to a new position (see later), the resistance R3 in the circuit over wiper fs7 being of such a value that relays TR of several final selectors may operate in parallel. TR locks up over a second winding. Relay E released by C removes the short-circuit on C so that this'relay re-operates. Transmission of the quotation. The contacts of the price switches FA-FC are connected to transformers TT in the outputs of amplifiers AM connected to photo-electric cells PE influenced by the records SB. The record bands which are driven simultaneously, transmit one digit per revolution followed by a pause, contacts FO being closed during the pause. When FO next close after the final selector has been set, KA pulls up and makes a circuit for HA which is ineffective until FO open again. HA then switches through the first pair of wipers of the final selector so that the output of the record selected by price switch FA is impressed on the grid of valve SV and transmitted back to the calling party. When FO close and open again, KB and HB operate in turn, the second pair of wipers of FS are switched through to price switch FB, relays KA and HA being released to disconnect the first pair of wipers. The second digit of the stock is thus transmitted followed in similar manner by the third when KC, HC are operated. A further closure and opening of FO operates CX, CD. Release. The switch train is released in known manner when the calling party replaces his receiver, but if he does not, the operation of CD (see preceding paragraph) releases TR and A followed by B and C. The final selector is restored to normal by forward stepping of the rotary magnet R over a self-interrupting circuit AR closed by B, the selector then dropping and restoring to rotary normal, CX and CD being released by off-normal contacts. The relapse of B causes release of the groupselector and line finder in known manner, and LR also releases, but as the calling line is still looped, CO locks up over the loop and brings in an alarm including lamp LP. The number of callers using the apparatus at any time can be ascertained by pressing key BK. Setting the price switches. Dials PD1-3 set by an attendant in accordance with the stock price, each open - circuit a particular lead connected to control banks fa3-fc3 of the price switches. If the price switches do not correspond to the dials and if relay CH is not operated by seizure by a final selector, the magnets FADM-FCDM of the price switches step until correspondence occurs. During the stepping, relay CP operates in series with the magnets and opens the circuit over wiper fs7 of the final selector to ensure that relay TR does not operate even if the change key CK also in the circuit of TR is closed.