Phase-Shift Oscillators

This paper describes a type of resistance-capacitance-tuned oscillator which operates with a single tube. A three- or more mesh phase-shifting network is connected between the output and input of an amplifier tube. When the gain of the amplifier is adjusted either manually or by an automatic-volume-control circuit barely to maintain oscillation, almost pure sine-wave output is obtained. Variations in the basic circuit have been analyzed and design formulas are included in this paper. Experimental work verified theoretical expectations. A typical oscillator was found to have a distortion of 0.1 per cent at an output voltage of 20 volts.