GB563113A - Electron discharge device circuits - Google Patents

Abstract

563,113. Thermionic valves. STANDARD TELEPHONES & CABLES, Ltd. Oct. 16, 1942. No. 14509. Convention date, Oct. 23, 1941. [Classes 39 (i) and 40 (v)] An electron discharge tube of the type described in Specification 547,193 comprises a primary cathode 17, Fig. 5, control grid 18 and primary anode 19 having a small aperture 30 through which an electron beam can proceed towards an auxiliary electrode 20. A secondary emitting electrode 22 and collector grid 21 are disposed to the side of the direct path from the cathode 17 through the aperture 30. Electrode 20 need not repel the electrons as in the previous Specification, since this is performed by a variable magnetic field. This field may be parallel to the axis of the tube as shown, or, as shown in Fig. 8, may be perpendicular to that axis, preferably making an angle of 4 degrees with collector grid 21. The magnetic field in Fig. 8 may be in either direction. As in the previous Specification, a connection between the secondary emitting electrode 22 and the primary control grid 18 gives the tube a flipflop characteristic, the tube when switched on acting as an ordinary triode. In this case, however, the control is not by the grid 18 but by a variation of the magnetic field. Further increase of the field above the value necessary to deflect electrons on to electrode 22 may again switch the tube off. In a pulse counting circuit, a number of tubes 101-105, Fig. 10, are connected in a ring and the control coil for any one tube is partly made up by externally excited coil L1 and partly by the anode inductance L2 of the preceding tube ; control impulses applied to terminals 50 will only switch a tube on if the preceding tube is conducting. As soon as this occurs, the voltage impulse through a condenser C2 switches off the preceding tube. In the form shown in Fig. 5, a small anode current is necessary to keep the tube in operation and in order to obtain a completer cut off in the primary triode the arrangement shown in Fig. 12 may be adopted. Here the triode is divided into two parts, of different spacing, grid 18a co-operating with anode 19a to give a triode section with complete cut off, while grid 18b and anode 19b produce the switching effect. In an oscillation generator tuned anode coil 60, Fig. 13, acts also as the control coil for the tube. Thus, as soon as the tube becomes conducting, it is switched off again by coil 60 and oscillation is thereby sustained. The output voltage may be taken from coupling coil 80.