How do metal detectors work?

 Introduction

    Metal detector is made by applying advanced technology, which has the characteristics of wide detection degree, accurate positioning, strong discriminatory power, easy operation and so on. Metal detector is mainly used to detect and identify buried metal objects. In addition to its military applications, it is also widely used in: security checks, archaeology, prospecting, looking for scrap metal, but also it is a good helper for waste recycling. 

    Metal detector using sound alarm and instrument display, detection depth and the area of the metal being probed, shape, weight have a great relationship, in general, the larger the area, the greater the number of the corresponding depth of detection is also the greater; Conversely, the smaller the area, the smaller the number of the corresponding depth is the smaller. The maximum depth of detection listed in the table below, according to the product's corporate standards with a one-dollar coin buried in dry soil in the measured results.

    Metals buried in the ground, through a thick layer of soil to detect, inevitably affected by the geological structure. The stratum contains a variety of minerals, they will also make the metal detection signal, the signal of these minerals will cover up the signal of the metal and create an illusion. Used the old metal detector people have this experience, with the probe near the earth, stone, brick will sound the alarm, this phenomenon is called "mineralization reaction". For this reason, the old metal detector can only detect the metal in shallow soil, on the deeply buried metal targets can not help. But today's metal detectors are equipped with advanced ground balance system, can exclude the "mineralization reaction" interference, greatly improving the instrument's detection depth and effect.

The principle of metal detectors

    Metal detector using the principle of electromagnetic induction, the use of alternating current through the coil, resulting in rapid changes in the magnetic field. This magnetic field can be inside the metal object can sense the eddy current. The eddy current in turn generates a magnetic field, which in turn affects the original magnetic field, triggering the detector to emit a chirp. The accuracy and reliability of a metal detector depends on the stability of the frequency of the electromagnetic transmitter, which generally operates at frequencies from 80 to 800 kHz. The lower the operating frequency, the better the detection of iron; the higher the operating frequency, the better the detection of high-carbon steel. The sensitivity of the detector decreases as the detection range increases, and the magnitude of the induced signal depends on the size of the metal particles and the electrical conductivity.

    Sensitivity control can help control the magnetic field of the detection coil and mitigate the effects of electromagnetic interference on it. In the event of interference, reduce the sensitivity of the magnetic field generated by the detection coil can reduce the impact of external electromagnetic interference, so that the detection work normally.

The technical parameters (PK0075 as an example)

    Coin detection depth is 9 inches (in coin size for example) Signal frequency is 7.69KHZ Ground balance adjustment 3 beeps for target ID (high, medium, low), target identification indicator 5 frames, target identification ID, 0-99 scale number, all-metal mode, to reach the deepest depth Accurate positioning mode Searching mode Recognition mode Conductive curved display with target confirmation display Straightforward Intuitive user interface Enhanced elimination of ground ore interference Headphone socket 9V square battery Operating ring mirror: -20 ℃ ~ 60 ℃

Main advantages (take PK0075 as an example)

1. Shield the interference of surface minerals

     All soil contains minerals. The signals emitted by surface minerals can interfere with the signals emitted by the target detection object. The amount and composition of minerals vary greatly from soil to soil, so the user needs to "correct" the detector according to the specific soil conditions of the site.

    The PK0075 has both an automatic and manual surface cleanup function, which allows the user to eliminate the interfering signals of most types of land matter. If you need to maximize the accuracy and depth of the detector, you can use the Ground Grab Surface Clearing Calculator to carefully calibrate the detector to the soil conditions of the site.

2. Blocking signals from trash

    When detecting coins, users want to avoid detecting aluminum foil or nails, by observing the target ID of buried objects and listening to the beeps from the detector, they can determine which are trash and which need to be excavated. Alternatively, the user can use the detector's discrimination function to exclude non-target objects.

      3.Identify submerged objects

    The two digits on the display can help users identify metal objects. There are 99 scales from 01 to 99, indicating the relative conductivity of the detected object. The higher the number, the higher the conductivity. Ferrous objects are usually of lower value and show a smaller number on the display dial, while silver coins usually show a larger number on the display dial.

4. Positioning Function

    Using the locate function, you can locate the target object more accurately and determine the depth of the target object. When using the positioning function, do not move the detector, so that not only can locate the target, but also help to determine the general outline of the target object.

 How to get the best detection effect (take PK0075 as an example)

    When the soil is dry or the metal is buried farther back in time, the detection effect will be improved. The further the age of the buried metal, the deeper the detection depth. Because the metal buried in the ground for a long time gradually oxidized, resulting in metal rust to the surrounding spread and the surrounding soil reaction, resulting in a strong magnetic field, so that the area of the metal to increase, but also to increase the strength of the signal. The longer the signal strength will be greater, the deeper the detection depth will be.