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The effect of voltage on an oscillatory circuit loaded by a negative resistance is shown and a method for measuring very small voltages is described. The superregenerative detector for amplitude modulation possesses limiting action and tends to reject ignition noise. The importance of the shape and frequency of the quench voltage is considered. Selectivity conditions are studied. Selectivity is low for broadcast and high for short-wave frequencies compared with a nonregenerative circuit. Superregenerative circuits are more susceptible to shot noise than conventional circuits, and this becomes important if preamplifiers are used. Because of back modulation, reradiation can be present even with mixer tubes in front of the superregenerative stage. An analysis of the frequency spectrum produced by a super-regenerative oscillator, when a frequency-modulated signal is applied, is presented. It is shown that the oscillator output consists of a band of frequencies each component of which is deviated in the same amount and direction as the incoming signal. The use of two slope-tuned superregenerative stages in push-pull as a balanced frequency demodulator is described and explained. The superregenerative stage represents a very efficient amplifier for frequency modulation signals. Two frequency-modulation receivers are described in which the superregnerative tube is used as an amplifier.