The theory of the generation of alternating currents by means of triodes

The numerous circuits which have been suggested from time to time for the generation of alternating current by means of triodes are found by analysis to depend on the same basic principles. The present paper is intended to cover the essential features of the subject, and is an endeavour to solve some of the difficulties on original lines and to offer an explanation of the characteristic behaviour of triodes in conjunction with generator circuits. The problems connected with the generation of alternating current arise in particular in the production of high-frequency currents for wireless purposes, and, in order that the deductions may have practical utility, reference is often made in the context to the special requirements, of wireless transmitting apparatus. After a brief study of the characteristics of a triode or high-vacuum valve provided with three electrodes, viz. anode, grid and incandescent filament, the general circuit is considered and the factors determining the frequency of the generated current are established. The particular limitations imposed by the triode and the conditions under which it is operated are then examined. It is shown that there is a definite maximum output to be obtained, and the requirements of the circuit for maximum output are investigated. The power obtainable under any given condition is determined. The design of a circuit to meet a specification is laid out and experimental confirmation is given. Finally a graphical method of analysis is evolved to show in diagrammatic form the conditions under which triodes may and do operate.