A metal detector uses a physical principle known as eddy current. The principle itself is simple enough to understand. A metal detector is equipped with a balanced electromagnetic system. The metal detector sends waves parallel to the sensing disc.
The waves then cross all the materials they encounter. When they detect a metal, the waves are returned and perceived by the detector. It then emits a sound and visual signal, which shows the nature of the metal and its conductivity. The heavier the metal, the stronger the signal.
As you can see, the principle is simple but effective. There are then important criteria that come into play in the choice of your detector. A metal detector buying guide will help you determine your profile and the ideal detector depending on the terrain.
Key factors when selecting a metal detector
When buying your metal detector, there are four main criteria to take into account. These criteria will obviously determine the value of the metal detector. These include power, discrimination, beach mode and versatility.
The power of a detector is important because it allows you to search deep and therefore effectively. This is the value expressed in KHz that must be considered. The higher the value (in 12-15KHz for an entry-level detector), the better the detector will perform. The higher the power, the greater the search depth.
Discrimination is also a major factor. It involves applying research filters on certain types of metals. If you only want your detector to beep on gold for example, you discriminate everything else. Almost all detectors today offer a more or less effective system of discrimination.
This function allows selective detection through the elimination of all ferrous metals during research (iron, steel, nails, capsules) The device will then search for non-ferrous metal objects.
The discrimination on a detector is not the guarantee of being able to discover all the precious pieces, the jewels of small sizes. Use the discrimination carefully so as not to miss small but interesting objects. A detector whose discrimination is set to eliminate a tin of a liter will also reject a piece of coin or a ring, even in gold.
In addition, the performance of the device is lowered by about 20 percent. It is also noted that in discrimination, a small non-ferrous object placed under a larger ferrous object will not be detected. The all metals mode remains the most efficient mode in the majority of cases.
Beach mode (range)
This mode is important because it will allow you to search on beaches. The conductivity of the saltwater can disturb the detector and it must therefore be equipped with a system to overcome this effect, otherwise farewell detection by the sea. Generally, this mode is called beach.
If you want to handle detection by the sea, also consider checking the tightness of the disc. You may end up putting your detector in the trash because of the wave or spray.
A detector must be able to work on different terrains: forests, meadows, plowing, walls, seaside and underground.
There is also talk of ground corrections for detectors. On mineralized ground, some detectors can be inefficient. There is then a ground effect correction mode that corrects this anomally and compensates for the variations.
Some detectors are equipped with a rocking function with “Norm” search (normal) to Black sand search, which work on highly mineralized terrains, such as beach edges, wet sand or black sand.
False signals, irregular noise from interference (radio, high voltage lines) that is stabilized by reducing the sensitivity.
Soil effects are interferences caused by the different types of soil and their compositions. These generate false signals that are detrimental to the search. A soil is mineralized when the oxides it contains form an opaque screen disturbing the wave transmission.
The new generation devices are now equipped with a ground effect compensator to eliminate these interference effects. The best adjustment to mitigate the effects is noted by a perfect stability both in the air and approaching the ground with the disc. This setting must be changed regularly as you move to better exploit performance.
These settings can be automatic (instigated by a microprocessor according to the analysis of the received signal) or manual (by potentiometer, remaining the best current system).
Ground balance – soil effect compensator, electronic balancing for the neutralization of mineralization effects, wet soil, black sand. Hot-Roch – heavily mineralized stones composed of metallic particles bringing false signals.
VLF is the acronym for differentiating metal detectors according to their operation. There are 4 families of metal detectors: BFO, IB-TR, VLF and pulsed induction. BFO (frequency beats): detectors designed before the Second World War with poor performance used to discover objects of very large sizes and very shallow.
IB-TR (induction – transceiver scale): reliable and precise detectors working at low and high frequency. VLF (very low frequency) (or also TR or IB): detectors working at very low frequency, which allows it to excel in discrimination and thus facilitates the identification of objects detected by the prospector.
On the other hand, high-frequency detectors are very powerful at the level of in-depth research but will have gaps in discrimination. Pulsed induction: detectors that provide spectacular performance and insensitive to soil effects. Unfortunately, they are not discriminated against and that is why they are abandoned by prospectors.
Frequency can vary from about 3khz to 20 khz depending on the model. The detectors mostly used by prospectors are low frequency detectors (VLF). Some manufacturers have successfully built devices operating on a 6.6 khz frequency providing both good sensitivity and decent discrimination in any environment.
Disc or reel
On the detector there is a winding that allows the transmission of signals to the device during the scanning. Its size is usually 20 centimeters in diameter but the discs must be interchangeable in order to target searches (small discs for more precision and larger discs for more depth). Disk GP means disk Great Depth.
In summary, these key aspects should be considered because they help answer the question – what to look for when choosing the best metal detector for the money?