Fundamental (Concepts ofFeedback ontrol
James E. Maisel · 1975
n theearly twenties theideaofpositive feedback was incorporated inone-tube receivers inorder toincrease thereceiver's gainandselectvity since theamplification factor ofthevacuumtube wassopoor. In1934, H.S.Black(11 wroteapaperexplaining the theorofthefeedback principle andhowstability ofamplification aswellasreduction ofmodulation distortion follow whenstabilized feedback isapplied toanamplifier. Forexample, Blackproved ex- perimentally thatwithnegative feedback itwaspossible tocontrol *e gainoftheamplifier to0.01dBwithachange inplate voltage from240to260volts andmaintain themodulation products at75dB belowthesigal output atfull load.