Patent GB-476088-A (GB)
Title: Improvements in or relating to digit registering and transmission equipment such as used in telephone systems
IPC: H04Q3/42
Filed: 1937-02-12
Abstract: 476,088. Semi - automatic exchange systems. STANDARD TELEPHONES & CABLES, Ltd., SNELL, M. S., and WRIGHT, E. P. G. Feb. 12, 1937, No. 4295. [Class 40 (iv)] In a keyboard-controlled register sender for use, for example, with the operator's circuits described in Specification 476,048, each register consists of 5 condensers, one of which is charged positively or negatively to register any digit value from 1 ... 0. The positive charge is given by a condenser of larger size. Registering number. The operation of any of the keys 2 ... 5 for the first digit, or any key for subsequent ones, energizes PP which charges the corresponding condenser negatively over CR or positively from 4C and also charges a condenser 2C. On the relapse of PP when the key is restored after the 1st digit, 2C discharges through X which locks and by means of its slave XX connects up the next register and grounds NUL. Similarly, after the 2nd and 3rd digits Y, YY, Z, ZZ are operated. If the operator keys anything but 2 ... 5 for the first digit, an NU signal is given over NUL PP is not operated. Transmitting number. On the operation of Z, X and Y are released and A begins to interact with AA. This is without effect until the operator energizes B which locks and thereafter each operation of A charges a condenser 2C1 and each release discharges this condenser through relays C ... E in turn and sends an impulse over the circuit IL. On the 1st impulse, C locks up but is released when D is operated by the 2nd. The 3rd energizes E which remains locked up causing C to remain locked after the energization of D by the fifth impulse. By this means, the register condensers are connected in turn to a test circuit comprising in parallel the relays P, Q which are oppositely polarized with the aid of rectifiers so that P responds to a + and Q to a - charge of the register condensers. Operation of Q causes impulse sending to cease by providing a locking circuit for A in series with Q (upper) and circuit PAL ... PCL to the operator's position. Apparatus therein removes ground from STL releasing B which releases PP to energize X, Y or Z and so cause the next register to be connected up. Operation of P on the other hand releases any of the-relays C . . . E that are operated and energizes R which locks up releasing P. As a result, five more impulses are sent after which C, D, E are all energized together and as a result Q is operated to stop the digit and initiate the association of the next register as described above. On the completion of sending, the operator removes ground from GD to release X, Y. Cancelling wrong registration. Operation of CA by the operator's cancel key energizes X if it is not energized already and discharges the first register. XX transfers the discharge circuit to the second register and energizes Y and YY transfers the discharge circuit to the third register. If impulses are already being sent, a circuit over FZL causes B to be released to stop the transmission. CA holds on long enough for complete cancellation after a momentary operation of the cancel key.