Constant current biased head driver

Claim 2

A circuit, comprising: a reactive load; a fixed AC bias source; a record signal source; constant current source means responsive to the two sources for supplying the reactive load with a constant current biased drive signal; and a bridge means integral with the constant current source means and cooperative therewith to double the available signal supplied to the reactive load.

Claim 3

The circuit of claim 1 wherein the constant current source means include operational amplifier means with positive feedback coupled at its negative input to the fixed AC bias and the record signal sources.

Claim 4

The circuit of claim 2 wherein the bridge means include; inverting amplifier means operatively coupled at its input to the operational amplifier means; and wherein the outputs of the inverting amplifier means and of the operational amplifier means are coupled across the reactive load.

Claim 5

The circuit of claim 3 wherein the fixed AC bias source includes: a DC record signal source; a chopper circuit for chopping the DC record signal at a selected bias high frequency; and means coupled to the chopper circuit for supplying the fixed AC bias to the operational amplifier means.

Claim 6

The circuit of claim 3 further including; AC coupling means for coupling the fixed AC bias and the record signal to the operational amplifier means.

Claim 7

The circuit of claim 3 further including; a resistor/capacitor coupled across the operational amplifier means negative input and output; said inverting amplifier means including an operational amplifier coupled at its negative input to the resistor/capacitor, and at its output to one end of the load; and said operational amplifier means being coupled at its output to the other side of the load.

Claim 8

A circuit for driving a head, comprising; operational amplifier means with positive feedback coupled to receive a given record signal and coupled at its output to the head; fixed AC bias means coupled to the operational amplifier means; and inverting amplifier means coupled to the operational amplifier means and cooperative therewith to double the current through the head.

Claim 9

A circuit for driving a head, comprising; operational amplifier means with positive feedback coupled to receive a given record signal and coupled at its output to the head; fixed AC bias means coupled to the operational amplifier means; and inverting amplifier means coupled to the operational amplifier means and cooperative therewith to double the current through the head.

Claim 10

The circuit of claim 7 wherein the operational amplifier means include; an output resistor coupled at the output thereof, a feedback resistor coupled from the output resistor back to the positive input of the operational amplifier means; and a third resistor coupled from the positive input to ground; wherein the feedback and third resistors maintain the voltage drop across the output resistor constant.

Claim 11

The circuit of claim 7 wherein the fixed AC bias means include; means for generating an AC square wave of relatively high frequency; means for forming an AC bias sinewave of fixed amplitude from the square wave.

Claim 12

A circuit for driving a record head, comprising; a source of record signal; an operational amplifier coupled at its negative input to the source having positive feedback for generating a constant current drive signal; bias means for supplying a fixed AC bias voltage to the negative input; an inverting amplifier for generating an output which is always out of phase with the constant current drive signal; and said operational amplifier and inverting amplifier outputs being coupled to respective sides of the record head.

Claim 13

A circuit for driving a record head, comprising; a source of record signal; an operational amplifier coupled at its negative input to the source having positive feedback for generating a constant current drive signal; bias means for supplying a fixed AC bias voltage to the negative input; an inverting amplifier for generating an output which is always out of phase with the constant current drive signal; and said operational amplifier and inverting amplifier outputs being coupled to respective sides of the record head.

Claim 14

The circuit of claim 10 including; step-up transformer means coupled between the record head and the outputs of the operational amplifier and inverting amplifier.

Claim 15

A circuit for driving a record head, comprising: a source of record signal; a fixed AC bias source; and a constant current source comprising an operational amplifier with positive feedback coupled at its negative input to the fixed AC bias and record signal sources to supply a constant current biased drive signal to said record head.

Claim 16

A circuit for driving a record head, comprising: a source of record signal; a fixed AC bias source; and a constant current source comprising an operational amplifier with positive feedback coupled at its negative input to the fixed AC bias and record signal sources to supply a constant current biased drive signal to said record head.