SU488168A1 - Magnetometer - Google Patents

Description

one

The invention relates to the field of measurement technology and may be used in magnetic magnetometry for measuring magnetic fields.

A magnetometer is known which contains a measuring probe with Hall sensors, balancing resistors, a source of alternating voltage, an amplifier and a recording device. However, for a well-known magnetometer, due to the temperature and time drift of the parasitic resistive component of the residual voltage, zero is possible, which violates the accuracy.

The purpose of the invention is to improve the accuracy of the magnetometer.

The proposed magnetometer, in contrast to the known, is equipped with series-connected narrowband amplifier, control unit and adjustable voltage source, the output of which is connected to the input electrode of the Hall sensor, and the input of the narrowband amplifier to the corresponding output electrodes of the Hall sensor. The Hall sensor can be made with five electrodes: two input electrodes, located at the ends of the plate, and Thermal output, located in the middle of the plate on its side edges, so that the dimensions of the measuring probe can be reduced.

The electrical circuit of the magnetometer is shown in the drawing.

The magnetometer contains a measuring probe 1 with a Hall sensor 2, -representative

a semiconductor wafer with two input 3 and three output 4 and 5 electrodes. The input electrodes of the Hall sensor are located at the ends of the plate, and the output electrodes are. In the middle of the plate at its

lateral gran x. An adjustable variable-to-on variable source 6 is connected to the input electrodes. The output electrodes 4 are connected to the input of the registering device 7 through an amplifier 8 with adjustable gain. The gain control of the amplifier 8 is controlled by the feedback circuit 9, the feedback coefficient of which is changed by the signal taken from the shunt 10.

A balancing resistor 11 is used to equalize the potentials of the electrodes 4 in the absence of a 1 magnetic field, and to balance the alignments of the electrodes 4 and the 5 balancing resistor 12.

In order to regulate the control current depending on the ambient temperature, the proposed magnetometer provides for a link regulated by 1, -the component of the narrowband amplifier 13 with a large gain factor and the control unit

14, the output signal from which is supplied on the day of the controllable variable source 6 of the alternating voltage. When the measuring probe is connected to a source of alternating voltage, a control current flows through the Hall sensor.

In the absence of a magnetic field and a fixed ambient temperature with the help of balancing resistors 11 and 12, an initial alignment of electrode electrodes 4 and 5 is performed. A control / supercurrent flow occurs through the measuring probe and a certain Go temperature of the Hall sensor is set.

The measurement zone is introduced into: a magnetic field whose induction is to be measured. At the output electrodes 4 of the Hall sensor, a voltage appears proportional to the measured magnetic field induction, which is amplified and fed to the input of the recording device 7. This voltage can be represented by the expression:

t / and. 7, /,"R . / eye B,

; i)

where k - coefficient of proportionality;

x —ustandon Hall; / control - control current of the Hall sensor; kyc - amplifier gain

measuring path; B - induction of the measured magnetic

the floor

From equality (1) it follows that the condition for the proportionality of the output signal of amplifier 8 is only the induction of the measured: magnetic zero is

Const.

(2)

To fulfill the condition (2), the voltage of the amplifier 8 is proportional to the control current of the Hall sensor, in order to adjust the gain of the amplifier 8.

When the ambient temperature changes due to the temperature dependence of the physical parameters of the Hall sensor, a potential redistribution occurs on the Hall sensor electrodes, which is accompanied by the appearance of a potential difference on electrodes 4 and 5. A signal is input to the input of amplifier 13, amplified by this amplifier, and through the control unit 14 enters the circuit control variable voltage source 6. Size and gender

the output signal of the control unit 14 depends on the magnitude and direction of the temperature change of the Hall sensor from the initial value of Go. The output of the control unit controls the source of the variable

tension As a result, the control current of the Hall sensor increases or decreases depending on the sign of the deviation of the element temperature from the initial value of Go. The process of changing the current ynpaiBlong continues until the temperature of the Hall sensor reaches its initial value of Go.

Since the Go temperature of the Hall sensor is reached at a control current different to

from the current /yiip.o, in order to fulfill the condition (2), it is necessary to change the gain factor of the amplifier 8 in the direction opposite to the change of the control current. For this purpose, from the shunt 10 connected to the control circuit

the measuring probe, the signal is removed, which is proportional to the control current, and is fed into the feedback circuit 9 of the amplifier 8.

Formula of invention

Claims (2)

1. A magnetometer containing a measuring probe with a Hall sensor, balancing resistors, an alternating voltage source, an amplifier and a recording device, characterized in that, in order to improve accuracy, it is equipped with a series-connected narrowband amplifier, a control unit and an adjustable source of | M voltage , the output of which is connected to the “entrance” of the Hall sensor sensor, and the input of the narrow-band amplifier — to the corresponding output electrodes of the Hall sensor. 2. Magnetometer according to claim 1, characterized in that, in order to reduce the size of the measuring probe, the Hall sensor is made with five electrodes: two input electrodes located at the ends of the plate and three output electrodes located in the middle of the plate x J