Improvements in or relating to electrical circuits and electronic tubes employed therein

Abstract

Abstract 632,168. Thermionic valves. INTERNATIONAL BUSINESS MACHINES CORPORATION. Sept. 23, 1946, No. 28409. Convention date, Nov. 27, 1945. [Class 39 (i)] [Also in Group XL (b)] In a gaseous discharge device in which the discharge is triggered by applying a positive potential to the control grid 12, Fig. 1, the cathode 11, control grid 12 and anode 10 being enclosed.in a box-like shield grid 13 having a window 15 for passage of the electrons, a rod-shaped auxiliary anode 16 is inserted between the control grid 12 and anode 10 ; the auxiliary anode is connected to a resistance 28, Fig. 2, and a normally open switch R1a is provided for connecting the main anode 10 through a relay coil M<1> ... M<6> to the positive end of the voltage source. A plurality, e.g. six (as shown) of these discharge devices G<1>-G<6> may be utilized in the circuit arrangement of Fig. 2, which acts as a distributer. Initially the tubes G<1>-G<6> are all biassed below cut-off by negative voltages applied to their control grids, the shield grids being positively biassed; an input signal of the form shown in Fig. 3 is applied across the resistance 25 and at the points 1, 3, 6 (Fig. 3) the shield grids will be driven so negative that none of the tubes G<1>-G<6> will ignite, even with a positive potential on their control grids, whereas at the signal peaks 2, 4, 5 there is no potential drop across the resistance 25 due to the signal, and the tubes G<1>-G<6> can be ignited by biassing their control grids positively. Positive pulses are applied to the control grids in succession from a sweep circuit arrangement comprising vacuum tubes V<0> ... V<7>, energized by the input signal, and each tube G<1> ... G<6> ignites or fails to ignite according to whether the shield grid potential is positive or negative due to the input signal shown in Fig. 3. Thus for the signal shown in Fig. 3, tubes G<1>, G<3>, G' are not ignited and tubes G<2>, G<4>, G<5> are ignited. The arcs of the ignited tubes extend initially between the cathodes and auxiliary anodes, but at the time the control grid of the tube G<6> is made positive a voltage wave from transformer T<5> ignites gas discharge tube G' and energizes relay R<1>, so closing contact R1a; as a result, relay R2 is energized and contact R2a is opened; this has the effect of transferring the arc from the auxiliary anodes of the tubes G<1>-G<6> to their main anodes. Means are also described for restoring the circuit to its original starting condition. Specification 632,165, [Group XL (b)], is referred to.

Inventors

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