Carrier-erase magnetic tape recording

Claim 1

APPARATUS FOR PROVIDING AN ELECTROMAGNETICALLY REPRODUCIBLE RECORDING OF AN ELECTRICAL CONTROL SIGNAL ON A MAGNETIC TAPE ON WHICH IS PREVIOUSLY RECORDED A CONSTANT AMPLITUDE, SINUSOIDAL SIGNAL HAVING A PERIOD AT LEAST FOUR TIMES THE PERIOD OF SAID CONTROL SIGNAL, SAID APPARATUS COMPRISING: AN ELECTROMAGNETIC RECORDING HEAD INCLUDING A WINDING HAVING A CENTER TAP AND FIRST AND SECOND END CONNECTIONS; MAGNETIC TAPE TRANSPORT MEANS FOR MOVING SAID MAGNETIC TAPE IN MAGNETIC RECORDING RELATIONSHIP PAST SAID RECORDING HEAD; AN ISOLATING TRANSFORMER HAVING A PRIMARY WINDING AND A SECONDARY WINDING; FIRST CIRCUIT MEANS FOR COUPLING SAID SECONDARY WINDING ACROSS SAID FIRST AND SECOND END CONNECTIONS; RESISTOR MEANS CONNECTED TO SAID CENTER TAP; SECOND CIRCUIT MEANS CONNECTED BETWEEN SAID FIRST END CONNECTION AND SAID CENTER TAP THROUGH SAID RESISTOR MEANS FOR PASSING A CONSTANT AMPLITUDE DIRECT CURRENT THROUGH ONE-HALF OF SAID RECORDING HEAD WINDING; THIRD CIRCUIT MEANS CONNECTED BETWEEN SAID SECOND END CONNECTION AND SAID CENTER TAP THROUGH SAID RESISTO MEANS FOR PASSING A DIRECT CURRENT THROUGH THE OTHER HALF OF SAID RECORDING HEAD WINDING; MEANS COUPLED TO SAID THIRD CIRCUIT MEANS FOR ADJUSTING THE AMPLITUDE OF THE DIRECT CURRENT THROUGH THE OTHER HALF OF SAID RECORDING HEAD WINDING WHEREBY THE FLUX LEVEL PRODUCED BY CURRENT FLOW THROUGH SAID FIRST AND SECOND CIRCUIT MEANS AND SAID WINDING IS OF A PREDETERMINED VALVE; FOURTH CIRCUIT MEANS COUPLED TO SAID PRIMARY WINDING FOR SUPPLYING TO SAID PRIMARY WINDING A SIGNAL HAVING A FREQUENCY NOT LESS THAN TEN TIMES THE FREQUENCY OF THE PRE-RECORDED SIGNAL ON THE TAPE CARRIED PAST SAID RECORDING HEAD; AND FIFTH CIRCUIT MEANS CONNECTED TO SAID FOURTH CIRCUIT MEANS AND HAVING INPUT TERMINALS MEANS FOR VARYING THE AMPLITUDE OF THE OUTPUT SIGNAL OF SAID FOURTH CIRCUIT MEANS IN ACCORDANCE WITH VARIATIONS IN AMPLITUDE OF AN ELECTRICAL CONTROL SIGNAL APPLIED TO SAID INPUT TERMINAL MEANS.