An Analysis of Regenerative Amplification

This paper shows some of the defects of present theories regarding regeneration and presents a new method of analysis based on the idea of a power balance. It is shown that a signal voltage does not supply power to a regenerated circuit but merely prevents certain losses from occurring. This upsets the balance between power input from the tickler and power lost in the circuit, so that oscillation occurs. In other words, regeneration consists of self-oscillation started and controlled by the signal voltage. The amplification obtainable in this way has a definite limit, the limit being caused by variations in the plate and grid impedances of the vacuum tube, as the amplitude of the grid voltage increases. The rate of variation of these impedances as the grid voltages increases, depends on the tube and on the direct voltage used. The use of a grid leak and condenser decreases the voltage amplification, by increasing the rate of change of the plate filament impedance. In general, however, increased detecting efficiency more than makes up for the difference when audio frequency output is considered. The effect of resistance in the grid circuit is to decrease the amplification by increasing the effect of the impedance variations. It is found that the best turn ratio to use in a regenerated transformer is the same ratio that should be used in a non-regenerated transformer. The amplification obtainable increases rapidly as the strength of an applied signal is decreased.