Stabilized bias system for magnetic tape read and write heads

Claim 1

In a bias system for a plurality of high speed tape recorders, the combination of: a master reproducer having a first adjustable dc source providing a first dc signal, a first oscillator means providing a first high frequency ac signal, a first feedback loop for said first oscillator means, a second adjustable dc source providing a second dc signal as a reference signal for said first feedback loop, and a summing network having said first dc signal and said first ac signal as inputs and providing a master control signal as an output; and at least one slave recorder having a bias generator and a plurality of recorder amplifiers, said bias generator having a second oscillator means providing a second high frequency ac signal, a second feedback loop for said second oscillator means, a third adjustable dc source providing a third dc signal as a reference signal for said second feedback loop, a synchronization separator having said master control signal as an input and providing as outputs a fourth dc signal corresponding to said first dc signal and a third ac signal corresponding to said first ac signal, and means for connecting said third ac signal to said second oscillator means for synchronizing said second ac signal with said first ac signal; and each of said recorder amplifiers having a driver amplifier having two ac inputs and an amplitude control input, and providing a fourth ac signal as an output to a record head, with said second ac signal connected as one of said ac inputs, a third feedback loop for said driver amplifier, a fourth adjustable dc source providing a fifth dc signal as a reference signal for said third feedback loop, with said fourth dc signal connected as the input to said fourth dc source, and a signal amplifier having an externally generated audio frequency ac signal as one input and the return from the record head as another input, and providing as an output a sixth ac signal connected as the other ac input to said driver amplifier, with said fourth ac signal comprising a combination of an audio information signal and a high frequency bias signal.

Claim 9

A method of producing bias for a plurality of high speed tape recorders, including the steps of: producing a first adjustable dc signal and a first adjustable high frequency ac signal; combining the first dc signal and first ac signal to produce a master control signal; transmitting the master control signal to at least one slave recorder having a plurality of recorder amplifiers, at the slave recorder, separating the master control signal into a second dc signal corresponding to the first dc signal and a second ac signal corresponding to said first ac signal; generating a third high frequency ac signal synchronized with the second and first ac signals; in each of the recorder amplifiers combining the third high frequency ac signal and an externally generated audio frequency ac signal producing a fourth ac signal as an output to a record head; and controlling the amplitude of the fourth ac signal of all the recorder amplifiers as a function of the second and first dc signals.

Claim 10

A method of producing bias for a plurality of high speed tape recorders, including the steps of: producing a first adjustable dc signal and a first adjustable high frequency ac signal; combining the first dc signal and first ac signal to produce a master control signal; transmitting the master control signal to at least one slave recorder having a plurality of recorder amplifiers, at the slave recorder, separating the master control signal into a second dc signal corresponding to the first dc signal and a second ac signal corresponding to said first ac signal; generating a third high frequency ac signal synchronized with the second and first ac signals; in each of the recorder amplifiers combining the third high frequency ac signal and an externally generated audio frequency ac signal producing a fourth ac signal as an output to a record head; and controlling the amplitude of the fourth ac signal of all the recorder amplifiers as a function of the second and first dc signals.