best reviews metal detectors for gold
Interesting information about treasure hunters
What is a metal detector
Metal detectors are electronic induction devices that detect metal objects in a neutral or weak-conducting environment, i.e. in soil, water, walls, wood, clothing and luggage, in food, in the human body and The rapid development of microelectronics has made these devices compact, reliable and highly intelligent. The scope of metal detectors has expanded markedly and, in addition to purely professional and military applications, has also begun to encompass the field of entertainment, which includes the “treasure search” in the broad sense of the term.

The main applications of metal detectors that determine their design, functions, cost, etc. are next:



For the military, the metal detector is primarily a mine detector. It does not require the ability of the device to distinguish metals. Until recently, high sensitivity was not required, but with the advent of plastic mines the situation has changed: in a plastic or ceramic mine there was one irreplaceable metal part - a small spring in the fuse. Only a highly sensitive device can detect it. In addition, the mine detector should be all-weather, all-season, as easy to manage as possible and extremely reliable.
In security structures and forensics, the metal detector is now used more widely than anywhere else. Anyone has encountered similar devices at the entrance to a bank, airport or nightclub. First of all, it is a “gate” that can be found even small metal objects, and small metal detectors for personal inspection. They easily and with high accuracy localizes a suspicious object. Such devices are necessarily equipped with units of internal troops guarding places of detention. In the West, terrorists often practice sending letters containing explosives, mostly to the media. In an attempt to protect themselves from this, large institutions have special devices to check incoming mail correspondence.

Irreplaceable metal detectors in construction and in the process of repair work. Think about how to do without this device, if you need to make a project to reconstruct the old building, which lacks drawings of the location of beams and other supporting structures (you can not smash the monument of architecture anywhere); and if you need to trace how the pipeline or electrical cable passes in the ground (not to dig all around); or just you want to drill an electric drill hole in the wall of your house, then not knowing the location of the wiring can cost you your life. A metal detector will help save your life or get rid of unnecessary work.

Mining. especially native gold, the metal detector is simply irreplaceable. Many mines in America, Australia and other countries experienced a rebirth, when with the help of metal detectors, the productivity of miners increased tenfold. Russian gold miners are still waiting for such a “revolution”: metal detectors are just beginning to appear on the vast expanses of the Russian Saural.

The archaeologist metal detector will help to identify the most promising place for detailed excavations or will give an opportunity to extract interesting finds where continuous excavations are simply impossible for various reasons.
Instructions for the Garrett Ace 250 metal detector
The treasure hunters work side by side with archaeologists. You can’t compare the joy of discovery with anything, whether it’s the first ancient coin found, a ring lost centuries ago, or a treasure trove of ancient ornaments. Indeed, the treasure hunt captures everyone who picked up a metal detector. It was in the development of equipment for treasure hunters that the devices achieved the greatest perfection in sensitivity and discrimination (weeding out unwanted finds). The search for objects lost by people, a kind of “home archaeology”, in America has reached great scope. There are clubs of search engines and collectors, for example, buckles from belts or backwater. Special magazines are published. Abroad, there are dozens of firms producing equipment for treasure hunters.

What is a metal detector, and how does it distinguish metals?



A metal detector is an electronic device that detects the presence of metal without contact with it (due to the radiation of radio waves and the capture of secondary signals), and, having discovered, informs the fact of the operator (sound signal, moving arrows, etc.).

When the device is turned on, an electromagnetic field is created in the search head, which spreads into the environment, be it earth, stone, water, wood, air. On the surface of metals that have fallen into the range of the search coil under the influence of an electromagnetic field there are so-called vortex currents. These vortex currents create their own oncoming electromagnetic fields, leading to a decrease in the power of the electromagnetic field created by the search coil, which is fixed by the electronic circuitry of the device. In addition, this secondary field distorts the configuration of the main field, which is also captured by the device. The electronic circuitry of the metal detector processes the received information and signals the detection of metal. Vortex currents are formed on the surface of any metal objects or electrically conductive minerals. The definition of metal in an object is based on the measurement of the specific electrical conductivity of the object.

The difference between cheap and expensive models lies only in the methods of radiation of radio waves and methods of capturing and processing and interpreting secondary signals. A more expensive instrument can determine with a certain degree of probability the type of metal detected before it is extracted, determine the depth of its deposit, can be rebuilt from the minerals of the soil, and have many different additional functions, increasing the productivity and efficiency of search, which are not available in cheap devices.

In literature, the following basic approaches to the construction of metal detector scheming equipment differ:



1) BFO - beat frequency oscillation. The measurable parameter is the frequency of the LC generator, which includes the search head coil. The frequency is compared to the reference and the resulting varying frequency of beatings is displayed on the sound display. The circuitry of the devices is simple enough, the coil does not require precision execution. The work frequency is 40 to 500 kHz. The sensitivity of BFO devices is low with low stability of work and poor ability to adjust from moist and mineralized soil. The BFO method was used in mass-produced foreign devices in the 60s and 70s. Currently, this method is popular with radio amateurs and is found in inexpensive devices of Russian manufacturers. This can also include devices with direct measurement of frequency, well-implemented on microprocessors.

2) TR/VLF - transmitter-reciver / very low frequency (transmitter-receiver / very low frequency). The search head is formed by two coils, located in the same plane and balanced so that when the signal is sent to the transmitting coil on the exits of the reception room there is a minimum signal. The transmission coil is often activated into the LC-generator circuit. The measurable parameter is the signal amplitude on the receiving coil and the phase shift between the transmitted and accepted sinusoid signals. VLF is a variation of this method where the work frequency is reduced to 2 to 10 kHz.

VLF is a method that allows you to build highly sensitive devices with good metal discrimination by analyzing phase characteristics. The circuitry of the devices is quite complex, coils require precision balancing. Most of the serial devices, including computerized ones, are being built using this method. Discrimination of objects and de-construction of soil in such devices is done relatively simply with the help of phase-shifting chains.

The TR principle (or its TR/VLF variant) provides for analysis of the phase characteristics of the signal, so they all easily distinguish between black and non-ferrous metals, are adjusted from debris and soil. These devices have a high sensitivity and resolution ability, which depends on the diameter of the head - the larger the head, the deeper the detection, but the harder it is to look for small objects. The term TR discrimination is usually defined as metal recognition in static.

3) RF - radio frequency is a high-frequency version of TR, where the transmitting and receiving coils do not form a flat transformer, but are spread out in space and are perpendicular to each other. The receiving coil receives the signal reflected from the metal surface, emitted by the transmitting coil. This method is used in deep instruments and is characterized by insensitivity to small objects and lack of discernment of metals.

4) PI - pulse induction. In devices of this type, the search head coil is not part of the vibrational circuit. A pulse signal is sent to it from the triggering generator. The analyzed parameter is the time of the end of the transition process (the position of the rear front of the voltage impulse). There are no specific requirements for the design of the coil. The distinctive features of this method are: low working frequency of impulses (5-600 Hz), high energy consumption, insensitivity to the ground, poor metal recognition. The PI method is often used in underwater devices to reduce the influence of water.

5) OR - off resonance. The analyzed parameter is the amplitude of the signal on the coil of the vibrational circuit, tuned close to the resonance with the signal sent to it from the generator. The appearance of metal in the coil field causes either to achieve resonance or care of it, depending on the type of metal, which leads to an increase or decrease in the amplitude of vibrations on the coil. This method, like BFO, was developed by radio amateurs, but there is no information about its use in serial treasure-hunting devices.

As the design of the device becomes more complex and its cost increases, the device’s ability to recognize a metal object without digging is improved. When the cost differs several times, the sensitivity of the detectors increases slightly (most often it is 20 - 45 cm for coins and about 1 - 2.0 m for large finds). However, complex devices equipped with processors can give a very approximate conclusion about the metal and depth of the find.