Variable frequency phase shift oscillator

Claim 1

IN COMBINATION IN AN OSCILLATOR: A DIFFERENTIAL AMPLIFIER HAVING A PAIR OF SIDES EACH CONNECTED TO RECEIVE AN INDIVIDUAL SIGNAL, THE DIFFERENTIAL AMPLIFIER BEING EFFECTIVE TO AMPLIFY THE DIFFERENCE BETWEEN THE SIGNALS INTRODUCED TO SAID SIDES AND PRODUCE AN AMPLIFIED SIGNAL HAVING CHARACTERISTICS REPRESENTING SUCH DIFFERENCE; PHASE SHIFTING MEANS INTERCONNECTED WITH SAID DIFFERENTIAL AMPLIFIER FOR SHIFTING THE PHASE OF SAID AMPLIFIER SIGNAL, SAID PHASE SHIFTING MEANS BEING RESPONSIVE TO THE FREQUENCY OF SAID AMPLIFIED SIGNAL FOR SHIFTING THE PHASE OF SAID AMPLIFIER SIGNAL BY AN ANGLE DEPENDENT UPON THE FREQUENCY OF SAID SIGNAL, FIRST MEANS CONNECTED TO SAID PHASE SHIFTING MEANS TO PRODUCE A FIRST SIGNAL HAVING A PARTICULAR AMPLITUDE AND A SECOND SIGNAL HAVING A VARIABLE AMPLITUDE AND A FIXED PHASE DIFFERENCE FROM SAID FIRST SIGNAL, SECOND MEANS INTERCONNECTED WITH SAID FIRST MEANS TO PRODUCE A RESULTANT SIGNAL HAVING A PHASE ANGLE THAT IS SUBSTANTIALLY EQUAL TO THE PHASE SHIFT PRODUCED IN SAID PHASE SHIFTING MEANS AT SAID FREQUENCY OF SAID AMPLIFIED SIGNAL, SAID SECOND MEANS BEING INTERCONNECTED WITH ONE SIDE OF SAID DIFFERENTIAL AMPLIFIER TO FEED SAID RESULTANT SIGNAL TO SAID SIDE FOR AMPLIFICATION OF THE DIFFERENCE BETWEEN THIS SIGNAL AND THE SIGNAL INTRODUCED TO THE OTHER SIDE, AND FEEDBACK MEANS INTERCONNECTED WITH THE OUTPUT FROM SAID AMPLIFIER MEANS TO FEED A PORTION OF THE AMPLIFIED SIGNAL FROM SAID AMPLIFIER BACK TO THE OTHER SIDE OF SAID AMPLIFIER MEANS.