A high-precision micro-particle metal detection dds circuit

Abstract

The invention relates to a high-precision microparticle metal detection DDS (Direct Digital Synthesizer) circuit. The high-precision microparticle metal detection DDS circuit comprises a power supply, a biasing amplification circuit, a transformer, a detecting coil and a feedback circuit, wherein the transformer is adopted for being coupled with a feedback oscillation circuit to produce sine waves, an LC oscillation loop formed by connecting a primary side coil in the detecting coil with a capacitor in series is taken as a frequency selective network, a DAC (Digital-to-Analog Converter) is added in a feedback loop to precisely regulate the feedback intensity of amplitude of the sine waves, the detecting coil also comprises a primary side coil and a secondary side coil, the primary side coil is not connected with a circuit, the secondary side coil is wound on the outer surface of the primary side coil and connected with the circuit, and the feedback circuit is formed by connecting the output terminal of a DAC digital chip controlled by a single chip microcomputer with two-stage operational amplifiers connected in series and a peripheral circuit and then with the emitting electrode of a triode in the biasing amplification circuit. The high-precision microparticle metal detection DDS circuit provided by the invention is high in anti-interference capability and detection precision as metal detection is positioned in the best sensitive region, and good in stability.

Description

technical field [0001] The invention relates to a high-precision tiny particle metal detection DDS circuit, which is a weak signal detection circuit for detecting metal from non-metallic granular or massive materials. Background technique [0002] At present, metal detectors generally use the principle of balanced coils to detect various metals. magnetic metal. The metal detector using this method generally consists of three sets of coils inside the detection head, including the transmitting coil in the middle and the receiving coils at equal distances on both sides. Its working principle is: through the electromagnetic wave generator connected to the transmitting coil in the middle to generate a high-frequency alternating magnetic field, the induced voltages of the receiving coils on both sides in the idle state cancel each other out before the magnetic field is disturbed and reach a balanced state, once the metal impurities Entering the magnetic field area, the magnetic ...

AI Technical Summary

Problems solved by technology

[0003] Most of the electromagnetic wave generators in traditional metal detectors use RC or LC oscillators to generate sine waves as transmission signals. They use complete analog circuits. Although the circuits are simple and the functions are easy to realize, they have poor frequency accuracy, poor anti-interference ability, and stable It has many shortcomings such as weak performance and difficult parameter adjustment. Later, the phase-locked loop technology was used, and the frequency accuracy was greatly improved, but the process was complicated, the resolution was not high, and the frequency conversion and computer program control were not convenient.

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