Research Of Multivibrator Magnetometer Based On Amorphous Core

The measurement of magnetic field has been used in many technology fields, such as industry, agriculture, national defence, biology, space navigation. With the rapid development of science and technology, more demands have been made of the magnetic measurement. In recent years, already brought to the people universal attention with the amorphous alloy belts or the wires as the magnetic core sensor manufacture and the application. This is because the amorphous alloy must (for example permalloy) have the better soft magnetism performance in the magnetic aspect compared to the crystalline state alloy. Compares to the crystalline state alloy, the amorphous alloy has the following merit:1).High sensitivity;2).The characteristics of the rapid response that the cut-off frequency reach thousands of Hz;3).Can make small shapes that can be used to measure points magnetic field;4).High reliability, hysteresis also smaller prolonged use;5).Temperature changes still have high stability;6).With high permeability and small magnetic-field-induced magnetic anisotropy constant;7).Has a high resistivity;8).Have a very wide dynamic range;Based on the above amorphous alloy material characteristics, it has been widely used in modern magnetic field sensor. In this paper the design of multivibrator oscillation weak magnetic field sensor is a good application of the soft magnetic properties of amorphous alloy materials, which produced by the amorphous alloy ribbon as a weak magnetic field sensor signal induction original. Twines the magnetic field signal gathering coil on the amorphous alloy ribbons. Such manufacture is because the amorphous alloy ribbon CoFeSiB under the outside magnetic field function its resistance value to be able to have the very big change. On the other side, this amorphous alloy ribbon also has taken the magnetic field signal gathering coil magnetic core. Like this when the ribbon resistance value has change created two magnetic fields signals gathering coil inductance value to have the change. Achieve the realization by magnetic field value this non-electric value and the inductance value this non-electric value transformation which can distinguish to the sensor. This for carried on the magnetic field survey to lay the foundation.In the present paper applies the magnetic field survey basic electric circuit is a multivibrator circuit. This electric circuit has the structure simply, the stability good, the power loss is low and so on the characteristic. Obtained the widespread application in the modern magnetic field survey. In the present paper designs the amorphous alloy multivibrator weak magnetic field sensor has divided into the voltage value measurement and the frequency measurement two kinds. Respectively uses is carries on the survey to the output voltage and to the oscilation frequency the way to carry on the magnetic field survey.Regarding voltage measurement multivibrator magnetometers, we can divide into the electric circuit pokes head in, multibrator bridge circuit, the filter, enlarges the electric circuit, the demonstration output and the feedback circuit and so on several parts. This type magnetometer was transforms the magnetic field signal the DC voltage signal to carry on the survey. Demarcates its magnetic field - voltage measurement curve after the experiment in the magnetic field survey scope is the linear straight line. Introduced the feedback circuit afterwards, by increase feedback circuit reduced the sensor survey sensitivity, but has opened up the sensor measuring range and improved the sensor stability. The voltage measurement magnetometer survey magnetic field - voltage measurement curve and the fitting linear curve lips are proper may reach 99.95%. After enlargement factor adjustment, its sensitivity may achieve 10000mV/Oe. Its measuring range is - 1Oe ~ + 1Oe, the repeatability error is 0.29%.Regarding frequency measurement multivibrator magnetometers, we can divide into the electric circuit pokes head in, multibrator bridge circuit, frequency measurement and processing circuit the demonstration output and the feedback circuit and so on several parts. This type magnetometer is through directly carries on to multivibrator bridge connections steady frequency vibration oscilation frequency surveys realizes to the magnetic field survey. Because the split-ring measurement system stability is insufficient, needs to join the feedback circuit to adjust the sensor stability. The magnetic field - frequency measurement curve obtains which with the frequency measurement magnetometer is non-linear. The magnetic field value which needs to draw support from the singlechip to realize to the oscilation frequency survey and discovers through the magnetic field - frequency measurement curve surveys the frequency value which corresponds. This type magnetometer greatest sensitivity may reach 87.95Hz/Oe, the measuring range is - 1.5Oe ~ + 1.5Oe, the repeatability error is 0.17%.In the present paper designs more than two kinds of multivibrator bridge magnetometers both have the higher survey sensitivity. Moreover through joins the feedback circuit, strengthened the overall system stability, increased the magnetic field survey reliability. Enables these more than two kinds of multivibrator bridge magnetometers all very good satisfying to the weak magnetic field survey request.