SU842940A1 - Multispeed device for reproducing analogue information - Google Patents

Description

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The invention relates to instrumentation, in particular to magnetic recording equipment, and can be used in the construction of multi-speed equipment for reproducing analog information.

A device for reproducing is known that provides correction of the frequency response during reproduction at several speeds using cascaded correction amplifiers, the number of which corresponds to the number of speeds, and containing correction circuits connected to correction amplifiers by means of switchable elements.

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The closest technical essence to the present invention is a device containing a magnetic playback head connected to a preamplifier, the correction stage, in turn, contains an operational amplifier, the output of which is connected to the input of the terminating amplifier, and the non-inverting input through the first resistor to the zero bus, as well as a serial RC circuit, a second resistor, two separate capacitors, and three electrical circuits, each made of a resistor connected to the source of the FET pa to the LC-circuit flzj.

However, dp correction of the frequency response in the high-frequency region uses an LC circuit with low reliability and relatively large dimensions.

The purpose of the invention is to increase the reliability of the device while maintaining the minimum number of adjustments of the frequency response during the transition from one speed to another.

The goal is achieved by the fact that in a device for reproducing analog information containing series-connected

a reproducing magnetic head, a preamplifier, a correction stage, the second input of which is connected to the control unit, and a final amplifier; the correction stage includes an operational amplifier., the output of which is connected to the input of the final amplifier, and a noninverting next input - through the first resistor a zero bus, as well as a serial RC circuit, a second resistor, two separate capacitors, and three electrical circuits, each made of a resistor connected to the source of the field-effect transistor, are non-inverted the operational input of the operational amplifier is connected through the first capacitor with zero bus and to the drain of the field-effect transistor of the first electrical circuit, the resistor of which is connected through the second capacitor to the output of the operational amplifier and to the drain of the field-effect transistor of the second, electrical circuit the preamplifier, the output of the same operational amplifier is connected via the second resistor to the inverting input of the same amplifier and via a serial RC circuit with a drain of the field transistor the third electric circuit whose resistor is connected between the zero bus, the source of the same transistor and the inverting input of the operational amplifier, and the gates of all field-effect transistors are connected to the output of the control unit

FIG. 1 is a block diagram of a multi-speed analog data playback device DP; on. Fig. 2 is a schematic diagram of a correction stage when switching from one speed to another: Fig. 3 shows the formation of a frequency response in a correction stage.

A speeding device for reproducing analog information contains a magnetic reproduction head 1 (Fig. 0) associated with a preamplifier 2, which is connected to the input 3 of the correction stage 4, which is in turn connected to the control unit 5. The output 6 of the correction stage 4 is connected with terminal amplifier 7.,

The correction stage 4 (FIG. 2) contains an operational amplifier 8, the non-inverting input of which through

parallel connected resistor 9, the capacitor 10 is connected to the ground bus and simultaneously connected to the drain of the field-effect transistor 11 connected in series with the resistor 12, the field-effect transistor 13, resistor 14, while the drain of the transistor 13 is connected through the capacitor 15 to the output of the amplifier 8 that inverts entrance

through a resistor 16 connected to the ground bus and simultaneously through a series-connected field-effect transistor 17, resistor 18, capacitor 19 in parallel with them a connected resistor 20 is connected to the output of the same amplifier Control inputs 21 and 22 of the field-effect transistors M, 13 and 17 stored with control block 5 (Fig. 0.

A multi-speed device for reproducing analog information operates as follows.

The signal from the reproducing head 1 is fed to the pre wiring jack 2. The amplified signal from the output of the preamplifier 2 is fed to the input 3 of the correction stage 4, from the output 6 of which the signal is fed to the terminal amplifier 7.

The formation of the frequency response (fig.Z in the correction stage is as follows.

The frequency response from the mid frequencies f, 3 low

The f-j frequencies are formed by a feedback circuit consisting of a field-effect transistor 17, resistors 18 and 20, and a capacitor 19.

A change in the resistance of the channel of the field-effect transistor 17 when the corresponding control voltage is applied to its gate when switching from one speed to another provides a change in the frequency response boost in the low-frequency region and a change in the Transmission Ratio.

Claims (2)

The operadione amplifier 8, in conjunction with RC elements and transistors, forms an active resonant system, which forms the characteristic in the direction of high frequencies (parts f f. And f and%). A change in the resistance of the channel of field-effect transistors 13 and 11 when the control voltage is applied to their gates when switching from one speed to another provides a change in the resonant system and, accordingly, a change in the rise in the high-frequency region. A multi-speed device for reproducing analog information using one opamp, three field-effect transistors and two RC chips allows the required amplitude-frequency characteristics to be generated when switching from one speed to another. Switching from one speed to another does not require connecting other correction circuits. This makes it possible, in comparison with the known device, to reduce the number of circuit elements, which, in turn, makes it possible to simplify the design. Claims of the Invention A multi-speed device for reproducing analog information, comprising a serially connected reproducing magnetic head, a preamplifier, a correction stage, the second input of which is connected to the control unit, and a terminal amplifier, wherein the correction frame includes an operational amplifier, output which is connected to the input of the terminal amplifier, and non-inverting input - through the first resistor to the zero bus, as well as a serial RC circuit, the second resistor, two separate con A torus capacitor and three electrical circuits, each of which is made of a resistor connected to the source of the field transistor, characterized in that, in order to increase reliably. the operation of the device, the non-inverting input of the operational amplifier is connected through the first capacitor with zero bus and to the drain of the field-effect transistor of the first electrical circuit, the resistor of which is connected via the second; swap capacitor to the output of the operational amplifier and to the drain of the field-effect transistor of the second electrical circuit, while the resistor of the specified circuit is connected to the output of the preamplifier, the output of the same operational amplifier is connected via the second resistor to the inverting input of the same amplifier and field-effect transistor of the third electric circuit, the resistor of which is connected between the zero shindy, the source of the same transistor and the inverting input of the operational amplifier, and the gates of all field devices The anzistors are connected to the output of the control unit. Sources of information taken into account for the ppp examination 1.Patent US No. 3781488, cl. 179-100.2 K, published, 04/02/68. 2. USSR author's certificate number 660084, cl. G 11 V 5/02, 14.12.76 (prototype). 2J 15 it eight 18W 17 0 9 sixteen. 22 9G n S Yy -V,