Patent GB-417524-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone or like systems comprising coin box stations
IPC: H04M17/02
Filed: 1933-04-07
Abstract: 417,524. Automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., Connaught House, Aldwych, London.-(Assignees of Materiel Telephonique Soc. Anon. ; 46, Quai de Boulogne, Boulogne-sur-Seine, France.) April 7, 1933, No. 10432. Convention date, Sept. 28, 1932. [Class 40 (iv).] In a prepayment station the insertion of coins, which is effected before removing the handset, closes a contact p a number of times characteristic of their value and thus transmits impulses over the b-wire for setting a register switch sma-smd in the line circuit at the exchange. The record is transferred to a relay set T, U, F, and the register switch is sent home and subsequently re-set by metering impulses characteristic of the number dialled. If the two records do not agree, the call is broken down and the fee is returned when the receiver is replaced. The collecting and refund magnets En, Re are connected to the a-wire through oppositely directed rectifiers and are operated by connecting at the exchange rectified A.C. and battery respectively. In the case of toll calls the subscriber hangs up without inserting coins and the toll operator establishes a connection to the line over the circuit TOL. The value of the coins inserted is then signalled to her visibly and audibly. Collection and refund are controlled from the toll board by applying to the talking circuit different combinations of voice - frequency currents, voice frequency relays A-C in the line circuit then controlling the application of the appropriate control currents to the a-wire to the substation. Normal call. Relay L responds to the intermittent operation of the coin contacts p energizing Hp which locks over the interrupter springs of the register magnet SM and arranges for its energization at the end of each impulse. On the removal of the receiver, L, D, E pull up, Hp is cut off and the finder start-relay Fs is operated. The record on the register is transferred to relays T, U, F provided it corresponds to a definite fee and relay Lb is energized. When the line is found, Co cuts off L, D, the register goes home and releases E and R pulls up and releases Fs. When the called party replies, the metering impulses are repeated by M to the register magnet and to Im which at once locks up, energizes E and connects the interrupter Int to X. X pulls up at the first " make " and at " break " remains locked in series with Y which locks independently of Co so that the next " make shunts out Im which has been shunting the talking circuit. On the relapse of Co when the calling party clears, rectified alternating current (or a reversed battery) is connected via Ce to the a-wire to energize the collecting magnet En. The circuit is broken by the restoration of contacts m which are only operated while there are coins in suspense. Ce shunts out Y but holds X and the registering relays fall releasing Lb. The relapse of Ce brings down X, R and the register goes home releasing E. Fee not inserted or incorrect. If the position to which the register is set by the metering impulses does not correspond with the setting of relays T, U, F, the relapse of Im energizes Wn which locks (G having been energized at the beginning of the connection), releases X, Y, opens the b-wire to release the exchange switches and connects up NU tone. On the relapse of Co, L pulls up again to hold G and therefore Wn until the subscriber clears. When he does, battery via Ce and the a-wire operates the refund magnet Re. If no fee is inserted Lb, R are not operated. The call is broken down as before but no refund signal is sent. Unsuccessful and abandoned calls. The fee is refunded when the subscriber clears owing to the non-operation of X. Forced release after three minutes. At the expiry of the period, further impulses are given to the metering wire whereupon Bd pulls up and locks energizing Wn which releases the connection and connects up NU tone as previously described. Bd however holds X, Y so that the fee is collected when the subscriber clears. Toll calls. The operator establishes a connection to the line over TOL energizing Cp, Ab, Bc and the subscriber then inserts the fee, the operation of contact p being indicated to the operator by the flickering of the supervisory lamp and by a tone signal applied by the differential relay To each time it is unbalanced. If the fee is to be collected, she energizes the voice-frequency relays A, B over the talking circuit whereupon Ab falls and X, Y pull up and lock followed by Lb, R. If it is to be refunded, she energizes B, C whereupon Bc falls energizing Rm which releases X, Y if necessary. Collection takes place on the relapse of Cp when the plug is withdrawn, but a refund is given on the replacement of the receiver without withdrawing the plug. Premature dialling and fault alarms. Thermal relay Th is operated and gives an alarm if the coin controlling circuit is not operated correctly shortly after the relapse of Co, e.g. because of a fault or of failure of the subscriber to hang up after forced release. In normal operation, Ce pulls up in the coin controlling circuit to release Lb and shortly afterwards is released by springs m to release R which disconnects Th. Th is connected up also if the subscriber dials before Co pulls up, the relapse of D energizing R which locks up, and if the b-wire develops a ground fault, L, Hp being continuously energized.