Patent GB-139696-A (GB)
Abstract: 139,696. Siemens Bros. & Co., and Pettigrew, T. May 26, 1919. Semi-automatic exchange systems.-An operator's keyboard is directly connected in multiple to the cipher switches of several impulse-senders, each cipher switch being first moved to mark a depressed key and subsequently to its normal position during the transmission of impulses. Each impulse-sender is associated with a junctionseeker, which connects it to the junction over which the call is to be extended. In the system described, this junction is assigned by a B- switching-operator for use by a distant A-operator, and means are jrovided, as described in Specification 6664/13, for preventing the completion of the connexion unless the A-operator plugs into the proper junction. The hundreds, tens, and units keys H, T, U of the operator's keyboard K are connected in multiple to the cipher switches CS<1>, CS<2>, CS<3> of several impulsesenders, only one of which is fully shown. Each impulse-sender has a decade switch DS with three arms E, F, G for controlling the emission of the several sets of impulses, and a junction-seeker JS for connecting it to the assigned junction. An assignor AS connects an idle impulse-sender to the keyboard K and controls the operation of the junction-seeker JS. Connexion of keyboard to idle sender. The relay P of the assignor AS is normally energized over the arms B<1>, B<2>, B<3> of the cipher switches of an idle sender, and energizes relay Q, which causes relay L to close contacts l<1> - - l<6> to connect up the relays T<1> &c. and actuating-magnets D' &c. of the cipher switches. Control of cipher switches by keyboard. The depression of any hundreds key H closes contact h<3> in the circuit of magnet D', which rotates the switch CS<1> until the arm C<1> reaches the contact connected to the depressed hundreds key, when the relay T' is energized and arrests the switch. The switches CS<2>, CS<3> are set similarly by the tens and units keys. Connexion of idle impulse-sender to assigned junction. The operator depresses the assignment key CK of the junction to be used, thereby energizing the actuating-magnet D of the junctionseeker, which is rotated until the test relay R is energized over arm 3 in series with relay X, which connects the contact a of the impulse relay A to the group selector GW. Transmission of selecting-impulses. When each of the cipher switches has come to rest, a circuit is completed over contacts 6, 5, t<3> for the actuating-magnet D<4>, which moves the arms of the decade switch DS into their second position, in which relay V is energized over arm B<1> of switch CS<1>, and the impulse relay A in series with an interrupter SI<2> is connected to the actuating-magnet D<1> of the same switch. At each closure of the circuit by the interrupter, the impulse relay A opens the circuit to the group-selector, and the magnet D<1> moves the switch CS<1> one step. When the switch CS<1> reaches normal, after a number of steps complementary to its original setting, the arm B<1> opens the circuit of relay V, thus causing the magnet D<4> to move the decade switch on to the contacts of the cipher switch CS<2>, when the relay V is again energized and the impulse relay A is connected to magnet D<2>. After the transmission of the tens impulses corresponding to the setting of the switch CS<2>, the decade switch is moved to connect up the units cipher switch CS<3>. Disconnexion of operator's equipment from junction. After the transmission of the units impulses, the decade switch is moved to normal, and, just before it reaches this position, relay Z is energized and opens the holding-circuit of the relays R, X, thereby disconnecting the sender. Operation of assignor AS. As soon as the decade switch leaves its normal position, relays P, Q de-energize slowly, and the magnet D' moves on the assignor until an idle sender is found, when the relays P, Q are again energized. Preventing completion of connexion if A-operator has not plugged into proper junction. Just before the end of the tens impulses, a relay W is energized over arm B<2> and, by attracting its armature w, makes the holding-circuit of relays R, X dependent on a relay S, which is only energized if the A-operator has inserted her plug in the assigned junction. If the relay S is not energized, the relays R, X de-energize, and the selectors GW, LW are released, without affecting the operation of the impulse-sender. Connexion to manual board over certain levels of selector GW. If either of the hundreds keys corresponding to the levels of the selector GW leading to manual boards is depressed, the relay J is energized and causes the decade switch to move to its second position, although no tens and units keys are depressed.