SU1437810A1 - Linear converter of magnetic field - Google Patents

Abstract

The invention relates to the field of magnetic measurements and can be used in devices that control the quality of materials and products based on the results of their interaction with magnetic fields. The purpose of the invention is to improve noise immunity. The goal is achieved by introducing an amplifier of frequency-modulated signals, a frequency discriminator, and a capacitor into a linear magnetic field transducer, which ensure the noise-resistant conversion of the magnetic field of the sample into a frequency change, which is converted into a voltage. The converter contains magnetizing device 1, made in the form of electromagnet, control object 2, magnetically sensitive unit 3, amplifier 4 frequency-modulated signals, frequency discriminator 5, video amplifier 6, memory unit 7, made in the form of a television receiver, without antenna, high-frequency blocks and sound channel, sweep block 9, constant capacitor 12 and capacitor 17, performing the functions of a coupling capacitor. Image of magnetic relief, correlated with the internal structure of the object. 2, is reproduced in the Cartesian coordinate system on the screen of the video,,:, and rotary device. 2 silt, with S (L from h 00

Description

. one

1C

15

20

25

The invention relates to a technique of magnetic measurements and can be used in devices that control the quality of materials and products as a result of their interaction with magnetic fields.

The purpose of the invention is to increase the sensitivity (noise immunity) by introducing the B linear magnetic field transducer to accommodate frequency-modulated signals, a frequency discriminator and a capacitor.

Figure 1 presents the block diagram of the Converter I fkg.2 its structural diagram.

The converter contains a magnetizing device 1, made in the form of an electromagnet, a control object 2, a magnetically sensitive node 3, an amplifier 4 of frequency-modulated signals, a frequency discriminator 5, a view, a compiler b, a memory unit 7, a video monitoring device 8, made in the form of a broadcast telepision. receiver without antenna, high-frequency blocks to the sound channel j block 9 sweep, shift register 10, current keys 11, capacitor 12 constant capacitance C 8 ferrite core 13, gauge winding 14, winding 1: 5 magnetized } regulated DC source 16 and separation capacitor 17, Scanner is connected to blocks 7.8 and 3, Object, 2 controls are connected to device 1 and node 3, Coils 14 and 15 are placed on core 13, winding 15 is connected to register ten,

The converter works as follows,

The magnetizing device creates a magnetic field in object 2 of the coctol, as a result of which a magnetic relief is formed near its surface; 45 depends on the internal structure of the object of control and acts on the sensitivity-sensitive unit 3 of the converter. The shift register 10 alternately, through the current keys 11, supplies the sign-50 alternating current pulses to each magnetizing winding 15, due to which the cores 13 constantly oscillate from one saturated coil

either way.

To select the most optimal operating point, an adjustable DC power supply 16 is connected in parallel to the measurement site.

five

0

five

0

The coil 14 feeds a constant current into it, thanks to which a corrective constant bias field is induced in the core 13.

The separation capacitor 17 does not lead to any undesirable phenomena, since the ferrite cores in this case behave as linear devices (which is explained by the presence of a constant component in the magnetic field of the core), in which neither the magnetic rectifier effect can occur). Mleni, nor parametric generation.

In the absence of a measurable field, the value of inductance L, and, consequently, the resonant frequency ujp of the oscillating circuit of the measuring winding, corresponds to a certain minimum value of р р. The oscillatory circuit is the turns of the cores 5 connected to the measuring winding 14, to which the capacitor 12 is connected,

When there is a measurable field H directed along the core, the inductance of the measuring winding 14 increments UL, leading to a change in the resonant frequency of the oscillating circuit

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and YrsN j - gjp-cop -: -.

1LC. I (L + /) L) C

The obtained increment of the resonance frequency WP WP (H) of the oscillating circuit is converted into the emf as follows.

The signal from the magnetically sensitive node 3 is amplified by an amplifier of frequency-modulated signals 4 and detected in frequency discriminator 5, after which the increment of emf (4АС) p), taken from the output of frequency discriminator 5, is amplified in video amplifier 6, the video signal from the output which is recorded in block

7, in the converter, the electronic-mechanical times are carried out: - wrench of the test surface.

In the control process, the transducer moves at a constant speed relative to the surface being monitored. At the same time the video signal is accumulated

in the memory block 7, when interrogating elements of one line, it is periodically read from it by a signal from the scanning unit 9 with a period equal to the time of one frame and fed to the screen

31А378

video monitor 8, where it controls the brightness of the light beam. At the same time, the control voltage of the sweep unit 9 controls the displacement of the electron beam on the screen of the Spot Monitoring Device 8, in which the Cartesian coordinates reproduce the image of the magnetic relief correlating with the internal Q structure of the object 2 of the control.

Claims (1)

Invention Formula Linear magnetic field transducer containing magnetizing device, magnetically sensitive node, video amplifier, the output of which is connected to the first input of the memory unit, the scanner unit, the first output of which is connected to the magnetosensors Q g 0 ten the second node, the second output, to the second input of the power unit, the third output, to the first input of the video monitor, the second input of which is connected to the output of the memory unit, characterized in that, in order to increase the noise immunity, a frequency-modulated signal amplifier is inserted into it , a frequency discriminator and a capacitor, and the input of the amplifier of frequency-modulated signals is connected to the output of a magnetosensitive node, in parallel to which a capacitor is connected, the output of which is connected to the input of the frequency discriminator minator, the output of the latter is connected to the input of the video amplifier - l, and the magnetically sensitive node is designed as a single-line converter on ferrite cores x, / f