SU1543456A1 - Device for measuring parameters of magnetic record apparatus - Google Patents

Abstract

The invention relates to instrumentation. The goal is to improve measurement accuracy and enhance functionality. The device contains a control unit, the first output of which is connected to the input of the clock pulse generator, the output of which is connected in series with the control pulse driver, switch, triangular voltage generator, instantaneous function converter, controlled attenuator, magnetic recording apparatus under test, display unit. The remaining outputs of the control unit are connected to the corresponding inputs of the switch. The number of outputs of the driver of control pulses corresponds to the number of frequencies at which the parameters of the test apparatus are measured in the automatic measurement mode. The device operates in two control modes (automatic and fixed frequency mode), which expands its functionality. 3 il.

Description

The invention relates to instrumentation, in particular, to devices for measuring parameters of magnetic heads.

The aim of the invention is to improve the measurement accuracy and to expand the functionality of the device.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 - timing diagrams explaining the principle of operation of the device; in fig. 3 - timing diagrams explaining the principle of forming a periodic signal of a triangular shape.

A device for measuring magnetic recording parameters comprises a block 1

control, the first output of which is connected to the input of the generator 2 clock pulses, the output of which is connected to the driver 3 control pulses. The outputs of the driver control generator 3 are connected to the corresponding control inputs of the switch 4, through which the capacitor matrix 5 is connected between the inverting input 1 and the output of the operational amplifier 6. At the same time, the output of the operational amplifier 6 is connected to the first input of the summing element 7, the output of which is turn connected to the non-inverting input of the comparator 8. The inverting input of the comparator 8 is connected to

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zero potential. The output of the comparator 8 is connected to the input of the summing element 7, and through a current-setting resistor 9 is connected to the inverting input of the operational amplifier 6, the non-inverting input of which is connected to zero potential. The output of the operational amplifier5 is connected via a series-connected voltage converter 10 and a controlled attenuator 11 connected to the input of the magnetic recording apparatus 12 under test, the output of which, in turn, is connected to the input of the display unit 13. The outputs 2-17 of the control unit 1 are connected to the corresponding inputs of the switch 4. The number of outputs of the driver control generator 3 and switch 4 corresponds to the number of frequencies at which the parameters of the tested magnetic recording apparatus 12 are measured in automatic mode.

The device operates in two control modes (automatic and in fixed frequency mode) as follows.

In the automatic mode, the control unit 1, via output 1, turns on a generator of 2 clock pulses generating a sequence of one polar pulses of stable frequency (Fig. 2a), which are fed to the input of the driver 3 of control pulses having eight outputs. In addition, each pulse arrives at a separate output. For simplicity, FIG. 26, 2b, 2d depicts a sequence of three pulses. There are pauses between a series of pulses. The repetition rate of sequences of pulses is 20–25 Hz.

The control pulses from the outputs of the imaging unit 3 are fed to 1 to 8 outputs of the switch 4, through which the corresponding capacitor of the matrix 5 is connected to the negative feedback circuit of the operational amplifier 6. The operational amplifier 6 together with the matrix 5, the switch 4, the current-carrying resistor 9, a summing element 7 and a comparator 8. generates a sequence of triangular voltage signals with different frequency of variation of this voltage (FIG. 2d). The formation of a periodic signal of a triangular shape. we happen after

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blowing way. The signal at the output of the comparator 8 always has a maximum value, and its polarity depends on the polarity of the signal at the non-inverting input 2 and changes its sign at the moment of changing the polarity of the input signal. In the initial state (Fig. Pro, moment t0) the output signal comparator 8 takes one of the possible values, for example, a positive value of U0. The output signal of the comparator 8 is fed to the integrator input, consisting of a current-setting resistor 9 with resistance R of operational amplifier 6 and connected through switch 4 to the negative feedback circuit of capacitor C from matrix capacitors 5. The voltage at the output of operational amplifier 6 is connected with input id expression

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where T is the integration constant,

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The operational amplifier 6 is turned on in the inverse mode, therefore the voltage at its output has a negative polarity (Fig. 36). At the same time, the output signals of the comparator 8 and the operational amplifier 6 act on the corresponding inputs of the summing element 7, as a result of which the non-inverting input 2, comparator 8 is a total time-varying voltage that tends to zero (Fig. 3 Sv). When a zero voltage is reached at the non-inverted input 2 of the comparator 8 (fig. Sv, moment t.,) The output voltage of the comparator 8 abruptly changes sign and becomes equal to-U0 (fig. Over, time t,). From this point in time, the discharge of the capacitance from the matrix 5 through the resistor 9 begins. The voltage at the output of the operational amplifier 6 increases linearly (FIG. 36, the time interval t, - t g), and the voltage at the output 2 of the comparator 8 varies from maximum negative value to zero (Fig. 3 Sv, time interval t ,, - t). At the moment when the voltage at the input 2 of the comparator 8, which is the result of the addition in the summing element 7 of the output voltages of the comparator 8 and the operational amplifier 6, reaches zero, the output voltage i

the comparator 8 again changes its sign abruptly and takes the value plus U0 - (FIG. For, time t). In the following, the process is repeated, i.e. The output of the operational amplifier 6 is triangular-shaped, the frequency of which depends on the value of capacitance C in the feedback circuit of the operational amplifier 6 (Fig. 36). In the automatic mode of operation of the device, the pulses from the output of the generator 3 of the control pulses control the switch 4, connecting a certain combination of capacitors of the matrix 5 to the feedback circuit of the operational amplifier 6, as a result of which a sequence of triangular signals is generated with a predetermined frequency (Fig. 2e)

From the output of the operational amplifier 6, the signal is fed to the input of the voltage converter 10, which performs the conversion of a triangular (with a linearly varying amplitude) voltage, or sinusoidal. The inertia-free transducer 10, corresponding to a sinusoidal law, is provided by using an operational amplifier, the feedback circuit of which includes a diode-resistor circuit that does not contain energy-accumulating elements (capacitance, inductance). The sequence of sinusoidal signals (FIG. 2h) is then fed to a controlled attenuator 11, which serves to obtain the necessary amplitude ratios and power of the output signals. If it is necessary to receive signals of one frequency or another sequence of frequency changes using control unit 1 through output 1, the clock pulse generator 2 is turned off and the frequency and duration of the output signal are controlled in manual mode using the same control unit 1 through its outputs 2-17 .

The signal from the output of the controlled attenuator 11 is fed to the input of the test apparatus 12 of the magnetic recording, and from the output of the latter to the display unit 13, according to the indications of which the parameters of the test recording apparatus 12 of the magnetic recording are estimated.

Claims (1)

Invention Formula A device for measuring parameters of magnetic recorders, comprising a clock pulse generator, a switch and two output buses, the first of which is connected to the unit indications, characterized in that, in order to increase the measurement accuracy and enhance the functionality, a control pulse former has been introduced into it, capacitor array, operational amplifier, current-supply resistor, summing element, voltage converter, bus Zero potential1, controlled attenuator and control unit, the first output of which is connected via serially connected clock generator and control driver driver with the first control inputs of the switch, information the inputs of which are connected to the corresponding outputs of the capacitor matrix, the input of which is connected through a current-setting resistor to the comparator output, and also with the inverting input of the operational amplifier, the output of which is connected to one of the inputs of the summing element, to the input of the voltage converter and to the output of the switch, the second control inputs of which are connected to the second output of the control unit, the second input of the summing element is connected to the output of the comparator, the non-inverting input of which is connected to the output of the summing element, and the inverting input is connected to the bus. Zero potential, the output of the voltage converter is connected to the input of a controlled attenuator, whose VX ° D is connected to the second output bus. ,., /"but 04 but # A f Z / # 2 five 2 / four W