SU1439513A2 - Apparatus for measuring coercive force of magnetic materials - Google Patents

Abstract

The invention relates to magnetic measurements and can be used to monitor the coercive force of magnetically soft materials. The aim of the invention is to improve the accuracy of the control. This goal is achieved by introducing a current-collecting element 9, a delay unit 10, an analog switch 11 and a cyclic detector 12 into a known device, with the terminals of the current-collecting element 9 being connected respectively to the output of the signal pickup unit 3 and the first output of the controlled resistor 6. element 9 is connected to the input of the delay unit 10 and to the first input of the analog switch 11, the second input of which is connected to the output of the delay unit 10. The output of the analog switch 11 is connected to the input of the peak detector 12, the output of which is connected to the control output of the controlled resistor 6. The device also contains a magnetizing unit 1, a sample holder 2, a thyristor 5, a measuring element 4, a diode 7, a measuring unit 8. The supply of the known device with these elements makes it possible to measure the coercive force at the moment when the signal from the unit 3 is taken up to reach its peak value, which makes it possible to increase the accuracy of control. 4 il. - about S (L

Description

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The invention relates to magnetic measurements, can be used to control the coercive force of magnetically soft materials, and are additional to the author. St. No. 1325388.

The aim of the invention is to improve the accuracy of the control.

FIG. 1 is a block diagram of the device; FIGS. 2 and 3 are timing diagrams explaining the operation of the device; in fig. D - dependence of differential permeability on gender.

The device contains a magnetizing unit 1 with a controlled M sample 2, a unit 3 signal pickup, a measuring element 4, a thyristor 5, a control resistor 6, a diode 7, a measuring unit 8, a current collection element 9, a delay unit 10, an analog switch 11 and

peak detector 12,

In this case, a sample is placed in the magnetizing unit 1, the output of the signal removal unit 3 is connected to a series-connected current-collecting element 9, controlled by a resistor 6 and the intrusion electrode of the thyristor 5. The thyristor 5 is connected in parallel with the measuring element 4 connected in series with magnetizing

unit 1. The output of the collector element 9 through a serially connected delay unit 10, the analog switch P and the detector 12 are connected to the control input of the control resistor 6, the output of the measuring element 4 is connected via diode 7 to the measuring unit 8, and the control input of the analog switch 1I connected to the output of the collector element 9.

The device works as follows.

The magnetizing unit 1, in which the controlled sample 2 is placed, creates an alternating magnetic field of a triangular shape (Fig. 3, curve H, f (t)). Sample 2 is re-magnetized under the action of the field and in the block 3 of the signal removal the EMF E caused by the change of the magnetic flux in the sample 2, is induced. which has a maximum (peak) value at the moments of the remagnetization of sample 2, i.e. when the instantaneous values of the magnetic field become equal to the coercive force. The EC EMF through the controlled resistor 6 is fed to the control input of the thyristor 5, at the initial moment of operation of the device, when the resistance of the controlled resistor 6 is maximum, the amplitude of the control voltage of the thyristor of the control input of the tristor 5 is less than the threshold voltage and the thyristor voltage of 5 curve T is the dependence of the voltage on the thyristor control input on the field (the positive half-period of the change in the latter).

As a result, the signal from the measuring element 4 proportional to the current flowing through the magnetizing unit 1 and, therefore, proportional to the magnetic field, opens the diode 7 and enters the measuring unit B, during the positive half-periods of changing the magnetic field.

The emf E induced in block 3 by removing the signal causes a flow of current 1, proportional to Е (-, the amplitude of which is determined by the value of the resistance of the controlled resistor 6) in the circuit formed by the collector element 9 by the controlled resistor 6 and the control pn junction. and the resistance of the closed control transition of the thyristor 5 (Fig. 36, the dependence of the current in the thyristor control circuit over time (t)). At the output of the collector 9, voltage pulses of a polar polar styr proportional to the current pulses 1y in the control circuit are formed 5, which are received through the delay unit 10 and the open analog switch 11 to the peak detector 12. Moreover, the occurrence of the first pulse from the beginning of the device operation causes the peak detector 12 to appear at a constant level proportional to the amplitude of the incoming pulse and causing a corresponding decrease in the resistance value of the controlled resistor 6 and, as a result, an increase in the amplitude of the subsequent pulse at the input of the peak detector 12. As a result, over time, a stepwise increase occurs p voltage at the output of the peak detector 12 (FIG. Sv, the dependence of the voltage at the detector output on time (t)) and, accordingly, a stepwise decrease in the resistance of the controlled resistor 6. At the same time, the amplitude n r 3 increases in steps.

At the time t, the control electrode of the thyristor reaches the thyristor response threshold, i.e. at the specified time t, the resistance value of the variable resistor 6 is such that it ensures the thyristor to operate when the amplitude (peak) value of the signal from the removal unit 3 is reached.

At the moment the thyristor 5 triggers due to the opening of the control pn junction, the amplitude of the current pulse sharply increases (Fig, 3b, dependence (t), tt i), with the result that the amplitude of the signal at the output of the current-collecting element 9 becomes higher than the closing threshold of the analog key 11, the latter is closed and during the subsequent operation of the device at the output of the peak detector 12 is fixed constant level, Fitz (Fig. 3, the dependence Uv, f (t)), which maintains the resistance value of resistor 6 equal to R (reached at time t , -T), while the expense of the delay unit 10 is a voltage pulse from the output of the collector element 9, formed at the time t t, is fed to the input of the analog switch 11 after it has been closed and does not pass to the input of the peak detector.

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Thus, starting from the moment t ,, the triggering of the thyristor occurs in each period and the moment the signal reaches its peak value from the 3 unit, and the amplitude of the signal from the measuring element 4 is proportional to the coercive force (Fig. 3g, time dependence of the signal at the input of the measuring unit Uf (t)).

Claims (1)

Invention Formula A device for measuring the coercive force of magnetic materials according to ed. St. No. 1325388, characterized in that, in order to improve the accuracy of control, it is equipped a current collection element, a delay unit, an analog switch and a peak detector, the terminals of the current collection element being connected respectively to the output of the signal pickup unit and the first the output of the controlled resistor, the output of the current collector element is connected to the input of the block posteriorly and the first input of the analog switch, the second input of which is connected to the output of the delay block, the output of the analog switch is connected to the input of the peak detector, the output of which is connected to the control output of the controlled resistor. AND Phie I L) ff A V t Y ., { 4Ei /. 3 Air, (pi / 9. Compiled by A.Singchenko. Editor V.D. nko Tehred A.Kravchuk F L Proofreader I. Muska