Patent GB-306683-A (GB)
Title: Improvements relating to sending or controlling apparatus set by electrical impulses
IPC: H04Q3/42
Filed: 1928-02-07
Abstract: 306,683. Siemens Bros. & Co., Ltd., and Christian, D. A. Feb. 7, 1928 Automatic exchange systems, -In small systems of, say, 24 subscribers employing two-digit numbers and 25-point connectors, the two digits are received by a temporarily-used singlemotion register switch which is set to a position corresponding to the sum of the digits and subsequently moves to a position ,determined by the first digit and in so moving sends out a single train of from one to twenty-four impulses to set the connector. Thus, if the number 15 is dialled, the register is set to its 6th position and is then further moved forwards to its 1st position during which it sends out twenty impulses. The connector will thus, be set to its 20th contacts to which subscriber< >No. 15 must be connected. Similarly in response to the number 16 the register will be set to its 7th position and then will send out nineteen imputses. For numbers with a first digit 2, the marked contact which determines the end of impulsing is the 17th so that in response to the number 24 the register in moving from its 6th to its 17th position sends out eleven impulses setting the connector to its 11th position connected to subscriber 24. Provision is made for giving a special tone-signal if a non- existant number is called. Detailed operation for call to subscriber No. 15. The line relay L of a link circuit causes a hunting switch A - - D, Fig. 1, to select an idle register set, Fig. 2, whereupon relay PT operates over wiper A, register wiper SA in its normal position, contacts s4, a1, t1, and the right-hand winding of relay N. Relay A then operates over wiper B removing a short circuit from the lefthand windings of relays M, N. Relay M operates relay E over contacts a2, f1. On account of the first impulse, the release of relay A removes a short-circuit from relay F which on the succeeding operation of relay A completes a circuit a3, f2, e1, m3, n3, for the register magnet DM. At the end of the digit, the continuous short-circuiting of relay E over contacts f1, a2 cause this relay to release so that relay P. demoting a first digit 1, operates over wiper SB. At the first impulse of the second digit, contact a4 removes a short-circuit from relay G which operates so that the impulses will be repeated over contacts g3 to the magnet DM which will thus move wipers SA - - SD to their 6th position. At the end of the digit, the, continuous short-circuiting of relay F over contacts a4, g4 causes this relay to release, this being followed by the release of relays M, G. Relay S now operates over interrupter 10 and locks up, completing a circuit for relay AA in series with interrupter 11. At each closure of the latter interrupter, an impulse is sent over wiper C to the connector line relay LL and at the same time magnet DM is operated. After twenty impulses, wiper SC reaches the contact marked by relay P when relay T operates disconnecting relays AA, N. The release of the latter deenergizes all operated relays and closes a restoring circuit for the register switch. Dialling a non-existent number. The 24 subscribers are numbered 11-9, 19, 10, 21-29, 20, 31- 34. It a first digit greater than 3 is dialled none of the relays P, Q, R is operated and on the release of relay M at the end of the digit, a circuit is completed for the middle winding of relay U which connects up a " number-unobtainable " tone. No impulses are sent out since the operation of relay S is dependent upon the operation of one of the relays P, Q. R. If a first digit 3 is dialled and a second digit greater than 4, wiper SB on reaching its 8th contacts completes a circuit over contacts r4 for the left-hand winding of relay U which operates to connect up the tone circuit as before, at the same time opening the circuit of magnet DM and short-circuiting the impulse contacts aa2.