Patent GB-129163-A (GB)
Title: Improvements in and relating to Printing Telegraphs or the like.
Inventor: CARDWELL GEORGE ALEXANDER
IPC: H04L17/30
Filed: 1918-08-30
Abstract: 129,163. Cardwell, G. A. Aug. 30, 1918. Electric selectors.-The transmitter of a callbell system or a semaphore signalling system comprises electromagnetic relays adapted to be operated selectively in groups of three by the depression of a key, a relay energized upon each depression of a key, and an impulse sender controlled by the relay and adapted to send successively the three impulses selected by the relays in the correct order. The impulses are sent over one of two or both lines connecting the transmitter and the receiver, and the arrangement is such that two successive impulses of the same kind are not sent over the same line. Each line is provided with a polarized relay at the receiving station, and the first and second impulses select the operating magnet to be energized, white the third effects its energization. Holding circuits are established for the selected magnets of the receiver, which circuits are broken at. the cessation of the third or operating impulse to restore the receiver to its normal condition. When a station is arranged to receive and transmit, a magnet is provided which operates to break the circuits of the polarized relays of the station when the latter is transmitting. Transmitter. Each key 13, Fig. 10, of the keyboard is spring-controlled and mounted between stops 13<c>, 13d, and is provided with a depending portion 14 adapted to operate contact springs 20, 21 and 24 to close three circuits. The contacts closed by the depression of the A character key are represented by the lead 19<a>, contact 18, Fig. 1; the lead 23<a>, contact 22 and the lead 27 and contact 25. The operation of the keyboard selectively energizes three of twelve relays 28<1>, 28<2> - - 31<3> which are divided into four groups, and the common portion of the circuit of the relays contains a magnet 34, Figs. 1 and 2, and a magnet 36, Figs. 1, 2 and 13. The first relav of each group is adapted to be connected to the lead 19<a>, the second relay of each group to the lead 23<a>, and the third relay of each group to the lead 27. Each of the relays 28', 28<2> - - 31<3> controls a pair of circuit-closers 44, 45 and 44<a>, 45<a>, Fig. 2. The contacts 44 are connected to a positive lead 47 and the contacts 44a to a negative lead 48. The contacts 45, 45a of the relay groups 28<1>, 28<2>, 28' and 29<1>, 29<2>, 29<3> are associated with the line 11 and the contacts 45, 45<a> of the relay groups 30<1>, 30<2>, 30<3> and 31<1>, 31<2>, 31<3> are associated with the line 10. The order in which the impulses are sent to line is controlled by a group B of relays which also provides for a time interval between the impulses. The relay 34, Figs. 1 and 2, controls the operation of the group B of relays and the relay 36, Figs. 1, 2 and 13 controls the position of an earthing plate 78. The circuit connexions of the relays 28<1>, 28<2> - - 31<3> controlled by the keyboard are so arranged that successive impulses are not derived by the energization of two relays of one group. Receiver. A polarized relay 67a, Fig. 3, is placed in the line 11 and a polarized relay 69<a> in the line 10. These relays control the successive closure of contacts 71<a>, 72<a>, 73a, 74a, depending upon the nature of the impulse received and the line over which it is received. The selective closure of the contacts 71a, 74a, controls the energization from a source S, of four magnets 90', 91', 92<1> and 93' over normally closed contacts 86, 87, 88 and 89. The energization of the magnet 90' causes a contact-bar 96 to engage a bank of contacts 97, causes a pair of normally open contacts 98 to close, and also opens a pair of normally closed contacts 99. Similar operations are performed by the energization of the magnets 91<1>, 92<1> and 93<1>. A magnet 81 is placed in the common circuit of the magnets 90' - - 93<1> to close a holding circuit for these magnets at the contacts 100, and the magnet 81 is shunted by an inductance 81<a> to prevent the de-energization of the magnet between the successive impulses. This locking circuit includes a magnet 102 which, when energized, opens the contacts 86, 87, 88 and 89. When the second impulse arrives it causes a current to pass from the source S through the contacts of the energized polarized relay, through the normally closed contacts 86<a>, 87a, 88<a>, 89<a> and one of the normally closed contacts 98, 99<a>, 99<b>, or 99<c> to one of the magnets 104<11> - - 107". The energization of the magnet 104" closes a, group of contacts 108, 109, 110 and 111, and the other magnets control similar groups of contacts. The closure of one of the contacts 111, 111<a>, 111<b>, or 111<c> energizes a magnet 112 as follows :-one pole of source S, contacts 100, lead 101, contacts 101<a>, magnet 112, one of contacts 111, one of normally closed contacts 99, leads 94, and 95 to other pole of source S. The energization of magnet 112 opens the normally closed contacts 86<a> - 89<a>. The arrival of the third impulse over the line causes an impulse to be sent from the source S over one of the contacts of the polarized relays 67<a> and 69<a>, over one of the leads 82<d> - - 85<d>, through one of the contacts of the groups which have been closed by the second impulse from the source S, through one of the type-bar magnets and its associated contact bar 96, 96a, 96<b>, or 96<c>, a contact 122 at the extreme right of the bank of contacts 97, 97a, 97<b> or 97<c>, lead 117, magnet 114, and the lead 95. The energization of the magnet 114 closes contacts 115 which, with an inductive resistance 115<a>, is shunted about a pair of contact 101<a>. A magnet 116 is shunted across the resistance 115<a>, and when energized opens the contacts 101<a> in the holding circuit 101 of the energized relays. At the end of the third impulse the magnet 114 is de-energized, thereby opening the contacts 115, and as the contacts 101<a> are open the apparatus is returned to its normal condition. The inductive shunt 115<a> about the magnet 116 causes a delay in the de-energization of the magnet 116, and ensures that the contacts 101<a> are not closed before the contacts 115 are opened. Operation. To operate an apparatus A at the receiving station, the key A at the transmitting station is depressed to close the circuit of the relay 29', Fig. 1, at the contacts 18. 19<a> to close the circuit of the relay 28<2> at the contacts 22, 23<a>, and to close the circuit of the relay 29<3> at the contacts 25, 27. The relay 36, Figs. 1, 2 and 13 is also energized to break the circuit of the polarized relays 67, 69 of the transmitting station at the contacts 75, 76, 77 ; while the relay 34 of the relav group B is also energized. The energization of the relays 29', 28<2>, 29<3> closes the contacts 44, 45 and 44<a>, 45a of these relays, and the first impulse is sent from the lead 47 over the contacts 44, 45 of the relay 29<1>, contacts 63<b> of the relay group B to earth at 79, through the polarized relay 67<a>. Fig. 3, over line 11, through relay 67, Fig. 2. contacts 63<a> and contacts 44<a>, 45<a> of relay 29<1> tolead 48. The energization of the relay 34 closes the contacts 56 to energize a relay 49 which operates to close the contacts 57 to energize a relav 50. The energization of the relay 50 opens the contacts 63<a>, 63<b>, 63<c> so that the second impulse cannot be sent over the same path as the first. The relay 50 also closes the contacts 58 to energize the relay 51 which operates to energize the relay 52 by closing the contacts 59. The relay 52 operates to. close the normally open contacts 64<a>, 64b and 64<c> when a second impulse is sent from the lead 47 over the contacts 44, 45 of the relay 28<2>, normally closed contacts 65<a> of the relay group B, normally open contacts 64a, relay 67, line 11, polarized relay 67<a>, Fig. 3, at the receiving station, earth 79, contacts 64<b>, 65<b>, contacts 44<a>, 45<a> of relay 28<2> to lead 48. Hence the first and second impulses pass over line 11 in opposite directions. The relay 52 also closes contacts 60 to energize a relay 53 which operates to close contacts 61 to energize a relay 54. The relay 54 operates to open the normally closed contacts 65a, 65<b> and 65<c>, and closes contacts 62 to energize a relay 55. The relay 55 operates to close the contacts 66<a>, 66<b> and 66<c> when the third impulse is sent from the lead 47 over contacts 44, 45 of the relay 29<3>, contacts 66<b> of the relay group B, earth 79, through the polarized relay 67<a>, Fig. 3, over line 11, through relay 67, Fig. 2, contacts 66<a> and contacts 44a, 45<a> of relay 29<3> to lead 48. The three impulses received by the polarized relay 67<a>, Fig. 3, close in order the contacts 72<a>, 71<a>, 72a. The first closure of the contacts 72<a> energizes the magnet 91<1> as follows :-positive pole of source S, leads 95 and 94, magnet 91<1>, lead 83<b>, normally closed contacts 87, leads 83<a>, 83, contacts 72<a>, lead 80, magnet 81, to negative pole of the source S. The energization of the magnet 91<1> moves the contact bar 96<a> into engagement with the contact 97<a>, closes the normally open contacts 98<a>, and opens the normally closed contact 99<a>. The energization of the magnet 81 closes a holding circuit for the magnet 91<1 >at the contact 100, as follows :-positive pole of source S, leads 95, 94, magnet 91<1>, contacts 98<a>, lead 101, magnet 102, lead 101<1>, contacts 101<a>, lead 101<2> and contacts 100 to negative pole of source S. The energization of the magnet 102 opens the normally closed contacts 86, 87, 88, 89. The closure of the contacts 71a due to the second impulse energizes the magnet 104<11> as follows :-positive pole of source S, leads 95, 94. Magnet 104<11>, contacts 99, lead 82<c>, contact 86<a>, conductors 82a and 82, contacts 71<a>, lead 80, magnet 81, to negative pole of source S. The energization of magnets 104<11> closes the normally open contacts 108, 109, 110. 111, thereby completing the