What Is a Gaussmeter?

A Gauss meter (Tesla meter) made according to the Hall effect principle has a wide range of applications in measuring magnetic fields. This instrument is composed of a Hall probe as a sensor and a complete instrument. The size, performance and package structure of the Hall element in the probe play a key role in the accuracy of the magnetic field measurement. The Hall probe generates the Hall voltage due to the Hall effect in the magnetic field. After measuring the Hall voltage, the magnitude of the magnetic induction can be determined according to the Hall voltage formula and the known Hall coefficient. Gauss meter readings are in Gauss or Tesla. Gauss is a common illegal unit of measurement, and Tesla is a legal unit of measurement.

Hall effect Gauss meter

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A Gauss meter (Tesla meter) made according to the Hall effect principle has a wide range of applications in measuring magnetic fields. This instrument is composed of a Hall probe as a sensor and a complete instrument. The size, performance and package structure of the Hall element in the probe play a key role in the accuracy of the magnetic field measurement. The Hall probe generates the Hall voltage due to the Hall effect in the magnetic field. After measuring the Hall voltage, the magnitude of the magnetic induction can be determined according to the Hall voltage formula and the known Hall coefficient. Gauss meter readings are in Gauss or Tesla. Gauss is a common illegal unit of measurement, and Tesla is a legal unit of measurement.

(a) Surface magnetic field measurement of permanent magnets: Gauss meter (Tesla meter) is used to measure the surface magnetic field strength of permanent magnet products. It is mainly an evaluation of the quality of permanent magnet products and the consistency of magnetic properties after magnetization. Usually the magnets are measured The magnetic field strength at the center of the surface is measured. The standard sample data is compared to determine whether the product is qualified, and the consistency of the material can also be guaranteed.
(b) Measurement of air gap magnetic field: Gauss meter (Tesla meter) is widely used to measure air magnetic field, and it is used in scientific research, electronics manufacturing, machinery and other fields. Typical applications include motor and electro-acoustic industries.
(c) Residual magnetic measurement: such as the detection of the demagnetization effect after the workpiece is demagnetized.
(d) Magnetic leakage measurement: such as speaker magnetic leakage measurement.

The Hall effect on a current-carrying semiconductor wafer, plus a magnetic field B perpendicular to the surface of the wafer, a voltage will appear on both sides of the wafer, such as VH in Figure 1. This phenomenon is called the Hall effect. Discovered by Edward Hall in 1879. VH is called the Hall voltage.

This phenomenon occurs because the carriers in the energized semiconductor wafer are deflected and accumulated toward the lateral sides of the wafer by the Lorentz force generated by the magnetic field, respectively. Therefore, an electric field is formed, called a Hall electric field. The electric field force generated by the Hall electric field is opposite to the Lorentz force, which prevents the carriers from continuing to accumulate until the Hall electric field force and the Lorentz force are equal. At this time, a stable voltage is established on both sides of the film, which is the Hall voltage.

Make four electrodes on the chip, among them C1, C2 pass the working current I, C1, C2 are called current electrodes, C3, C4 take out the Hall voltage VH, C3, C4 are called sensitive electrodes. Each electrode is soldered with leads, and the chip is packaged with plastic to form a complete Hall element (also called a Hall chip). (1) or (2) or (3)

In the above formulas (1), (2), and (3), VH is the Hall voltage, is the resistivity of the material used to make the Hall element, n is the electron mobility of the material, and RH is the Hall coefficient, l , W, and t are the length, width, and thickness of the Hall element, respectively. F (I / W) is the geometric correction factor, which is determined by the geometry and size of the element. I is the working current and V is between the two current electrodes. Voltage, P is the power dissipated by the component. It can be seen from the formulas (1) to (3) that in a Hall element, , RH, and n depend on the material used in the element, and I, W, t, and f (I / W) depend on the design and process of the element. Once the element is manufactured, these parameters are constant. Therefore, equations (1) to (3) represent the results obtained by the three working modes of the Hall element. (1) represents current drive, (2) represents voltage drive, and (3) can be used to evaluate the maximum power that the Hall plate can withstand.

In order to accurately measure the magnetic field, a constant current source is often used to supply power to make the working current constant. Therefore, the magnetic induction intensity B of the measured magnetic field can be measured by the Hall voltage.

In some precision measuring instruments, a thermostat is also used, in which Hall elements are placed to keep the RH constant.

If the temperature of the use environment changes, constant voltage drive is often used, because compared with RH, n changes more slowly with temperature, so VH is less affected by temperature changes.

In order to obtain the highest output Hall voltage VH, the operating current can be increased, and the power consumption of the component will also increase. Equation (3) expresses the limit that VH can reach-the maximum power consumption that the component can withstand.

1) When the instrument is used in the measurement state, zero adjustment does not work or the measurement magnet has no reading, check whether the power supply is normal, secondly check whether the sensor is damaged, and whether the wiring is broken. If no defect is found on the inspection surface, the internal failure of the instrument requires Suppliers perform maintenance.

2) The sensor must not be stressed, hit or squeezed to avoid damage.

3) The sensor is placed away from the magnetic field during zero adjustment, otherwise it will cause measurement errors.

4) The instrument should be used under conditions that do not meet the environmental conditions of use.

5) During the measurement, it is found that the measured value does have a deviation. You can turn the handle on the back of the sensor to fine-tune the potentiometer to achieve the correct measurement result. ^[1]

1) Do not repair, disassemble and modify the Gauss meter without authorization.

2) Use a power supply within the specified range, and prohibit connection to a power supply outside the specified range.

3) It is forbidden to drop the Gauss meter and supporting sensors on the ground or give strong impact.

4) It is forbidden to touch the probe and the tip of the sensor by hand. It is strictly prohibited to heat the sensor, apply adhesive, and stick adhesive tape.

5) Gaussmeters are strictly prohibited in direct sunlight, high temperature and humidity, water, oil, dust, corrosive air, vibration and other places.

6) Strictly observe the use temperature range and storage temperature range.

7) It is forbidden to avoid the use of Gaussmeters when condensation occurs on the surface of the Gaussmeter (appears when you move from a cold place to a warm place).

8) It is forbidden to place Gaussmeters on machines that generate magnetic fields, especially magnetizers / demagnetizers / microwave ovens / welders / motors, etc. ^[1]

Gauss meter G100