Patent GB-191405841-A (GB)
Title: Improved Circuit Arrangements for Semi-automatic Telephone Systems.
IPC: H04M1/272
Filed: 1914-03-07
Granted: 1915-06-03
Abstract: 5841. Siemens Bros. & Co., [Siemens & Halske Akt.-Ges.]. March 7. Semi-automatic exchange systems.-In semiautomatic systems, the number impulses for setting the selectors on the wanted line can be repeated without the keyboard of the sender being reset. This arrangement enables an operator to correct the setting of her keyboard during the transmisson of the selecting-impulses according to. the original setting of the keyboard, and to ensure, by pressing a correction key, a repetition of the corrected number. A repetition of the impulses is also effected if the group selector fails to find an idle trunk to the selected group of connectors. This repetition may be continuously repeated until an idle trunk is found, or the repetition may be stopped by the operator by the depression of a key. When the trunk a, b, c is taken into use, for example by an operator at a distant manual exchange, the relays B, C are energized over the lead c, the lamp lr glows, and the relay A is energized over the loop circuit a, b, and contacts c7, b6, c5, and winding 3 of relay B. In response to the lamp signal, the operator moves her hand switch X to the contacts of the calling trunk, thus connecting her speaking-set HS to the trunk. After learning the connexion required, the operator sets her keyboard Ta, which is fully described in Specification 21,766/13, the depression of the units key closing a contact an, thus energizing a relay S, which locks up over contacts s2, 6, tl, and closes a circuit for the relays T, Q. The relay T (1) disconnects the calling line from the trunk a<1>, b<1>, (2) bridges the contacts c1, c2 of relay C, (3) connects the lead e<1> to the armature f4 of relay F, and (4) locks up over its contact t5. The relay Q closes a circuit for the relay F, lamp l, and the clutch magnet K of the sender N. The relay F (1) locks up in series with a relay E, (2)'disconnects the speaking set HS, and (3) connects the relay G to the trunk a<1>, b<1>. The magnet K clutches a rotating shaft to a shaft carrying the cams r1 ... r7 and a wiper O, which moves over contacts connected to the keys of the keyboard To. As soon as the cam r2 closes contact 2, the relay G is energized in a circuit which includes relay A, lead a', contacts c1, x1, f1, j<1>, resistance w, relay G, lead b<1>, contacts b6, c5, and winding 3 of relay B. The relay G locks up over its contact g3 and the relay B, and by closing contact g2 completes the impulse circuit from contact 1 of cam r1 over contacts j<1>, f1 to the lead a<1>. The relay A, controlling the vertical magnet H, is thus repeatedly earthed, until the wiper O engages the contact earthed by the depressed thousands key when the relay J is energized, and (1) locks up over a contact 7 opened after the transmission of each set of impulses, (2) disconnects the contact 1 from the lead a<1>, and (3) closes a contact j<3> which prevents the breaking of the holding-circuit of relay F at contact 3. At the end of the set of impulses, the contact 2 opens the circuit of the relays B, G, and the relay B energizes the rotary magnet D, which rotates the selector until a circuit is closed through the winding 3 of relay B and the test wiper. The relay B (1) cuts off the rotary magnet D, (2) disconnects the relay C from the test lead c<1>, (3) locks up over the lead c<1>, and contacts x4, f4, and (4) connects the calling line through to the next selector. The release of the relay C removes at contact c, the shortcircuit from the high-resistance winding of the relay T, so that the relay Q de-energizes and opens the circuit of the winding 2 of the relay F. The clutch magnet K remains energized over contact 4, and the rotation of the sender is continued until all the sets of impulses have been sent when the contact 6 opens the holding- circuit of relay S, which opens the circuit of relays T, Q so that a repetition of the transmission of impulses cannot take place. Operation if selector GWI cannot find an idle trunk. The speaking terminals in the last position are dead, but the test terminal e is connected to battery so that the relay B is energized as before but not the relay G, Since the contact g1 is open, the relay J cannot be energized, and the locking-circuit of the relays E, F is consequently opened at contact 3 at the end of the first set of impulses, and when the contact 6 is opened at the end of the last set of impulses, the relay S is not de-energized since the contact 6 is bridged by a contact e1. A repetition of the impulses can therefore take place. At the end of the first set of impulses, the relay F opens the circuit of relay B, so that the selector is released, the relays C, Q, Fare again energized, and the transmission of impulses proceeds as before. In order to prevent the repetition of impulses, the locking-circuit of the relay S may be opened by the key tl. Operation when keyboard is corrected during first transmission. After correcting the setting of the keyboard, the operator depresses the correction key tk, thus opening the locking-circuit of the relays E, F, so as to maintain the locking-circuit of the relay S. A repetition of the impulses therefore takes place as before. Connexion of operator to calling line before repetition of impulse transmission. If the operator realizes that she has set up the wrong number and cannot correct it without referring to the calling subscriber, she presses both keys tk, tl, thereby de-energizing the relay S, which opens the circuit of relays Q, T, F, so that her head set HS is again connected to the calling line.