Patent GB-349973-A (GB)
Title: Improvements in or relating to time controlling circuits for telephone or like systems
IPC: H04M3/12
Filed: 1930-03-05
Abstract: 349,973. Telephone systems. STANDARD TELEPHONES & CABLES, Ltd., Columbia House, Aldwych, London.-(Hatton, W. ; 46, Avenue de Breteuil, Paris, and Sano, K. M.; 18, Rue Boudewyns, Antwerp, Belgium.) March 5, 1930, No. 7208. [Class 40 (iv).] Metering; time controlling systems.-Predetermined intervals of time are measured by the cooperation of two switching mechanisms which are moved by periodic impulses of different frequency. As described the two switches co-operate initially and at 3-minute intervals thereafter to enable a third switch to make a complete revolution during which it transmits, to a subscriber's meter, impulses appropriate to the zone to which the subscriber's telephone line is connected. The subscribers are automatically disconnected after 12 minutes' conversation. Two eleven-point unidirectional switches S1 and S2 are stepped by means of interrupters at 2 second and 36 second intervals respectively. When a called subscriber replies relay N operates connecting magnet M2 to a contact of R2, wipers 29, 30 of S2 to a contact of relay R1, and operating magnet M3 from earth via the tone transformer T, and wipers 31 of S2 and 22 of S1 in their home positions H. If a 36 second period is about to commence relays R1 and R2 operate from the 2 and 36 second interrupters respectively and magnets M1 and M2 energize, the circuit of M1 passing via wiper 29 of S2. When the pulse ends magnets M1, M2 and M3 release stepping switches S1, S2 and S3 one step. When switch S3 moves off-normal, magnet M3 is connected to interrupter I and the switch S3 is stepped to its home position. During this movement wiper 39 transmits impulses to the subscriber's meter, the number transmitted depending on the zone to which the caller is extended. When the 36 second pulse is again received R2 re-energizes and M2 operates to step S2 and this continues until four periods have passed when the wipers of S2 are on terminal 2 recompleting a circuit for M1 over wiper 30. Switch S1 is moved under the action of the 2 second interrupter. When S1 has completed 17 steps a circuit is recompleted for magnet M3 and two seconds later S1 and S2 both move onto their next contacts M3 releases and S3 makes a complete cycle as before indicated to step the subscriber's meter. This cycle is repeated, the subscriber's meter being re-operated after 6 and 9 minutes have elapsed. After 18 periods have passed the wiper 29 of switch S2 reaches contact 5 and the circuit is recompleted for magnet M1 to step S1. When S1 has made 17 steps its wiper 26 completes a circuit for M2 and switch S2 steps onto contacts 6. The 36 second pulse also occurs at this moment but an automatic step is provided at this stage for reasons which will be apparent later. The circuit for M1 is again completed over contact 6 of S2 and switch M1 continues to step until contact 5 is reached in which position a tone T is extended over wiper 25 and conductor 47 to the calling subscriber to indicate that his 12 minutes is nearing completion. Ten seconds later wiper 25 extends earth over contact 10 and conductor 46 to release the automatic equipment. On release relay N falls back and switches S1 and S2 step home. If the relay N had energized during a 36 second period, instead of at the beginning as assumed above, the switch S3 would have operated at once as before to record the call and M1 would have responded to the 2 second interrupter and moved S1 a number of steps before M2 is energized. When M2 operates S2 moves breaking the circuit of M1 and S1 remains in the position to which it has been set. S2 now moves forward every 36 seconds and after 4 such periods the circuit is again completed for M1 which responds to the 2 second pulse and the call is metered after S1 has made a total of 17 steps. M1 then continues to move making 18 steps from its previous position before S2 again moves to break the circuit of M1. The calls are thus registered every 3 minutes from the commencement of the period with a 2 second accuracy. After 11 minutes 24 seconds have elapsed switch S1 is in position 3 and switch S2 is in position 5 and the switch S2 is stepped by a circuit over wiper 26 of S1 as described above although a 36 second pulse is not due. This ensures switch S2 being on contact 6 or 7 ten seconds before the conversation is disconnected and allows the disconnecting tone to be transmitted as described above. After 12 minutes S1 is in position 10 and switch S2 is in position 6 or 7, the call is disconnected and the switches homed as described above. If desired the switch S2 could be arranged to step automatically at the beginning of instead of during the last 3 minute period.