GB148582A - Improvements in ionic relays - Google Patents

Abstract

148,582. Eccles, W. H., and Jordan, F. W. June 21, 1918. Thermionic relays.-A thermionic relay or amplifying-apparatus for telegraphic or telephonic work comprises a pair or an even number of ionic valves connected in sequence by resistances with a return connexion so that the magnified potential difference along a resistance in the anode circuit of the last valve is communicated to the control electrode of the first valve to obtain amplification of the initial stimulus by retroaction. Fig. 1 shows a method of applying the principle using two three-electrode valves. When the electrical stimulus which it is desired to detect is impressed upon the grid circuit S of the first valve, the grid G<1> becomes more positive (for example) in potential relative to its filament. This causes an increase in the plate current of the first valve and consequently an increase in the potential difference between the ends of the resistance R'. The increased potential difference is transferred to the grid of the second valve so that it becomes more negative relative to its filament. Consequently the plate current of the second valve decreases, and the potential difference between the ends of the resistance R<2> in its plate circuit decreases also. This decrease is now transferred to the grid circuit of the first valve in such a manner as to makes its grid G<1> more positive relative to the filament. If, by adjustment, the resistances R<1>, R<2>, and the voltage factors E<1>, E<2>, are arranged so that the working condition of the set is one of instability, retroaction will continue until the plate current of the first tube reaches its maximum and that of the second tube its minimum value, and in order to restore the initial conditions it is necessary to interrupt the interaction of the valves. If, on the other hand, the set is adjusted for stable working, the electrical changes persist only while the outside stimulus is applied. In the modification shown in Fig. 2, a stimulus applied to the grid G<1> produces a change in potential along the resistance R'. This change of potential is of opposite sign from that initially imposed on the grid G', and being communicated to grid G<2> gives rise to a potential drop along resistance R<2>. This potential drop is of the same sign as the initial applied stumulus, and is transferred to grid G<1> to give a retroactive effect. An instrument I may be connected in either of the anodecircuits to indicate changes in current or voltage.. The batteries e<1>, e<2> in the grid circuits are introduced for the purpose of adjusting the grid voltages to suitable values. Any even number of valves may be used in cascade or independently grouped in pairs and combined in any suitable manner. In the typical two-tube arrangement the two valves may be replaced by a single duplexvalve.