Design Of Metal Detector Based On Balance Coil Technique

Metal detector is a kind of equipment for metal detection. It makes use of physical principles of electromagnetism and radial and gets induction signal for metal objects (iron, copper, stainless steel and so on) in mixture and body to effect an elimination and alarm. Metal detector now comes into many aspects of our everyday life. It is widely used in detecting from landmine underground to rare metal mine embedded under the earth, from food safety to rubber purity to lumber machining. It does work well in these fields and the improvement of its function is becoming to the main question customers care. At present high-precision metal detectors are mostly imported which are high powerful but expensive. With the development of modern industry towards high-precision and high-quality, high-precision metal detectors will have a very broad market. Therefore, there are very considerable economic benefits to develop a high accuracy and relatively low cost metal detector.This paper introduces the present situation of metal detectors and describes development elements and merits and drawbacks at home and abroad. According to the electromagnetic characteristics of the current coil, this paper analyzes and summarizes the distribution of magnetic field of the general balance coil, and deduces the variation along with the movement of metal into coils. Combined with the requirement of this topic, a rectangular balance coil is designed, which permutation alters to achieve an effective detection. Based on this theory, this paper offers a realizable scheme of an intelligent adjustment metal detector, composed of control circuit, probe, single chip, driven system etc. The design of control circuit and probe is more crucial. For the circuit part, the sine signal through the frequency adjustment, filter and amplification should have a stable frequency, a good waveform and a higher power. After the filter, amplification, signal adjustment, peak maintain etc, the signal acquired should be stable and can be able to reflect the characteristics of received signal parameters and have anti-jamming ability. For the probe part, the size and position of transmitting loop and receiving loops should be designed accurately to insure their credibility and stabilization.In this paper, the implementation processes and flow charts of the various modules are given as well as the flow charts of the entire system. Besides, some details of the metal detector are also described in the paper, including the design of the power supply part and the transmission part.The testing effect and function of this metal detector are shown through experiment in the subject, and some improvements are made. Finally, this paper prospects the trends of metal detectors and the application of new technology in metal detector.