Equivalent Circuits of an Electron Triode and the Equivalent Input and Output Admittances

This paper is presented in two parts. In Part I two fundamental equivalence theorems concerning a triode and its circuits are rigorously derived. These theorems give the simple circuits which are equivalent to the plate and grid circuits of the triode. These equivalent circuits contain only constant circuit elements and fictitious electromotive forces, the use of which greatly simplifies the calculation of currents in the triode circuits when the electrical variations are small. In Part II the equivalence theorems are used to obtain the equivalent input and internal output admittances of a triode with its associated circuits.