Patent GB-140506-A (GB)
Title: Improvements in or relating to lamp telephone relays
IPC: H04B3/36
Filed: 1918-12-05
Abstract: 140,506. Latour, M. Dec. 5, 1917, [Convention date]. Thermionic relays and repeaters.-A telephonic amplifying system for reciprocal working comprises two or more thermionic relays, an input transformer the primary windings of which are connected in series or in shunt between the lines, and an output transformer the secondary winding or windings of which are connected in shunt or in series between the lines. Formulµ are given for the ratios of transformation of the input and output transformers, and circuit connexions for the telephone of the relay operator are provided. Resistances are provided to prevent arcing in the reiay due to the unbalanced conditions of the lines. The input transformer 5, Fig. 2, is provided with two primary windings 8, 10 in the line L<1> and with two primary windings 9, 11 in the line L<2>; while the secondary winding of the output transformer 7 is connected to the common terminals of the windings 8, 9 and 10, 11. Resistances 12, 13 are provided to prevent arcing due to lack of balance between the lines L<1>, L<2>. The telephone apparatus 14, 15 and 16 of the relay operator is connected to the common terminals of the transformer windings 8, 9 and 10, 11. In the modification shown in Fig. 1, the output transformer 7 is provided two secondary windings 8, 10 in the line L', and with two secondary windings 9, 11 in the line L<2>; while the primary winding of the input transformer 5 is connected to the common terminals of the windings. The operator's telephone is connected in circuit by a separate transformer 16 the primary winding of which may be associated with the transformer 7. In the modification shown in Fig. 4, the primary windings 8, 9 of the input transformer 5 are connected between the lines L<1>, L<2>, and the output transformer is provided with secondary windings 23, 24 connected across the lines. In a further modification, the primary windings 8, 9 of the input transformer 5 are connected across the lines L<1>, L<2> respectively, and the secondary windings 23, 24 of the output transformer 7 are connected in the lines L<1>, L<2>. In the arrangement shown in Fig. 5, the relay 17 is shunted by the windings of an inductance 22 as described in Specification 131,704, and the telephone circuits of the relay operator are connected across the middle points of the windings. The telephone circuits of the operator may be connected by a transformer winding associated with the inductance 22. If m denotes the number of turns of the secondary winding of the transformer 5, p the total number of turns of the primary windings, y the apparent resistance of the grid circuit of the first lamp, and z the impedance on each side of the line, then, for the arrangements shown in Figs. 2 and 4, it should be arranged, in order to obtain the maximum excitation of the amplifier, that mp# = #v 2z, and for the arrangement shown in Figs. 1 and 3, that m p = #2y z. Also, if n denotes the number of turns of the primary of the transformer 7, q the total number of turns of the secondary, z the impedance on each side of line, and x the apparent resistance of the lamp 2, then for the maximum output of the amplifier for the arrangements shown in Figs. 2 and 4, it should be arranged that nq#=#2x#z, and for the arrangements shown in Figs. 1 and 3, that n q = # x#2z Specification 131,639, which describes a reversible relay, is referred to.