A Tunable Audio-Frequency Amplifier of Variable Selectivity
Edgar A. G. Shaw · Journal of Scientific Instruments · 1950
The Wien bridge network may be placed in the feedback path of an audio-amplifier to obtain frequency selectivity. The theory of teh design and operation of such an amplifier is developed with a view to obtaining variable selectivity and maximum stability of gain. A practical design is described, tunable from 30 to 20,000 c/s and capable of operation with good stability at effective Q values of 50-100 and for short periods with Q values in excess of 1000.