GB477757A - Improvements in and relating to generators for saw-toothed oscillations - Google Patents

Abstract

477,757. Valve generating circuits; electron multipliers. BRITISH THOMSON-HOUSTON CO., Ltd. July 7, 1937, No. 18932. Convention date, July 24, 1936. [Classes 39 (i) and 40 (v)] The rapid discharge of the condenser of a relaxation oscillator is effected by an electron multiplier. As shown in Fig. 1, the multiplier is of the form comprising a number of spaced secondary-emission electrodes 1 ... 4 in one plane, with intermediate electrodes 5 .. 7 in a parallel plane. The condenser 11 is charged from a battery 10 through a resistance 12 and is discharged through the electron path between the electrodes 3, 4. The electron stream 1 .. 4 is started by the impact of a cathode ray 20 on the electrode 1. The ray normally strikes the walls of a chamber 19, but when suitably deflected by the plates 17, 18 it passes through a hole in these walls and strikes the electrode 1. This occurs when the voltage on the condenser 11 has reached a desired value, one plate of the condenser being connected through the polarizing batteries 8, 9 to one deflecting-plate 17 and the other deflecting-plate being connected to a tapping on a resistance across the battery 10. As soon as the condenser has discharged, the ray 20 resumes its normal direction. The electrodes 1 ... 4 may be arranged as a regular polygon around a smaller number of plates 5 .. 7 also polygonally arranged, Fig. 2 (not shown). The primary beam may enter through an aperture in one of the electrodes. Instead of employing a cathode-ray tube as the source of the primary electron beam, the electrode 1 may form the anode of a thermionic valve, the grid of which is associated with the condenser 11 in such a way as to initiate a discharge through the valve when the condenser reaches a desired voltage. The electron multiplier may be of the to-and-fro type, Fig. 4, in which the multiplier plates 22, 23 are primed by an alternating voltage applied through a transformer 24. The condenser 11 of the relaxation oscillator is connected between the centre point of the transformer secondary coil and the ring anode 21. The multiplying effect starts suddenly when the anode 21 reaches a certain voltage, and ceases at a lower voltage. The discharges may be synchronized with an external source connected to the transformer 27, the secondary of which is connected to electrodes 25, 26 symmetrically disposed between the anode 21 and the multiplier plates 22, 23. The relaxation oscillation may be used for deflecting the beam of a cathode-ray tube of the kind in which the beam originates in an electron multiplier of the to-and-fro type. If the condenser 11 of the relaxation oscillator is discharged through an electron-multiplier of the same type, the same alternating-source 24 may be used for the two multipliers.