Shape
The shape of the coil (frame) of the metal detector.
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Round. The traditional form used in almost all types of ground and underwater metal detectors (see "Type"); the only exceptions are models that work according to the RF method (see "Operating principle"). When using concentric coils (see "Coil Type"), this option allows you to create a conical field, which is convenient for pinpointing the location of the find, but reduces the covered area and makes it difficult to search over a large area; models with DD coils do not have this drawback.
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Elliptical. The shape in the form of a longitudinally elongated ellipse allows you to somewhat "stretch" the field created by the metal detector in length. This is especially true for coils of the concentric type — however, such an expansion somewhat reduces the positioning accuracy of individual finds. But in coils of the DD type, where the accuracy is by definition low, the choice between round and elliptical shape is most often not fundamental.
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Rectangular. A specific form used in RF or PI instruments. For technical reasons, it is considered optimal for such devices, but it is practically not found in other types of metal detectors.
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Butterfly. Another option used in DD coils along with the ellipse (see above). In fact, it consists of two elliptical windings
..., partially combined and resembling butterfly wings in shape — hence the name. This option is typical mainly for large-sized DD coils; with a large width, it is considered more optimal than an ellipse.Detection frequency
The operating frequency (or frequency range) of the metal detector. This is one of the most important parameters when choosing a device, because the optimal frequency for different cases will be different — depending on the size and material of the items being searched, the characteristics of the soil and other factors. Detailed recommendations on the choice of frequency for each specific situation can be found in special sources; And already on the basis of this information, it is worth choosing a specific model.
Note that the actual frequency at which the metal detector will operate also depends on the installed coil — they are usually made for a specific frequency. Therefore, to use the full capabilities of the device with the ability to adjust this parameter, you may need replaceable coils.
Number of modes
The number of pre-installed programs for searching for various materials. Their number reflects the capabilities of a particular model, allowing you to start working right off the bat.
Search modes
Regular metal detector search programs include detection of coins, all metals, jewelry and relics. In some models, this list can be expanded with "Beach" programs, custom (user) detection mode, etc.
More features
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LCD display. The presence of its own display in the design of metal detectors. This feature makes working with the device more convenient and visual: through the display, you can display more different information than with the help of an audible alarm or indicator lights, and it is easier to perceive. On the other hand, such devices are more expensive than similar models without a screen.
— Arrow indicator. The presence in the design of the metal detector of an analogue dial indicator to display data on the search process. Such an implementation is much more modest and cheaper than the same LCD display, but an order of magnitude more convenient than without visual notification at all.
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Display backlight. The presence of a backlight allows you to use the display of the metal detector in low light conditions — up to complete darkness. Note that this function can be useful not only at dusk, but also in the daytime — for example, when searching in a dense forest in cloudy weather. See above for details on the display.
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Built-in speaker. The presence in the design of the metal detector of its own speaker. Such a speaker allows you to use the device without headphones, which are not always convenient, and sometimes unsafe (for example, when working in places where traffic can move).
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GPS module. The pre
...sence of a GPS satellite navigation module in the design of the metal detector. This module allows you to determine the current geographic coordinates of the device, and the options for using this data can be different: recording search routes, fixing the places of individual finds, and even full-fledged navigation with laying routes from point to point.
— Armrest. The presence in the design of the metal detector of an additional support in the area of the operator's elbow. This support reduces the load on the hand, and also makes the hold more stable and at the same time controllable, allowing you to comfortably hold the device in one hand.
— Headphone output. The presence of a headphone output in the design of the metal detector. This can be either a standard connector that allows you to connect any compatible "ears" (for example, a 3.5 mm mini-jack output, popular in portable audio equipment), or an original proprietary interface that allows you to use only specialized "native" accessories. Anyway, headphones are often more convenient than a speaker, as they allow you to hear the signals from the device well even in a rather noisy environment.
— Headphones. The presence of headphones in the scope of delivery of the metal detector. Usually, such headphones have high quality and accuracy of sound transmission, so that the user can be guaranteed to hear all the signals and tone shades of the signals. "Ears" can be wired and wireless, and in underwater models (see "Type"), they are, respectively, made waterproof. This function is convenient because you do not have to search and purchase the best headphones for the metal detector on your own.Power source
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AA. Replaceable elements, known colloquially as "finger" type. They can be both in the form of disposable batteries and in the form of rechargeable batteries. They are produced by many manufacturers, and different brands differ in price and quality, which gives many opportunities to choose the optimal option. And AA batteries are sold almost everywhere. On the other hand, they are usually required in large quantities — about 8, because metal detectors consume quite a lot of energy; and the elements themselves are most often not included in the set.
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PP3. Replaceable batteries of standard size, in a characteristic rectangular case with a pair of contacts at the end, nominal voltage of 9 V. They are more powerful than the popular AA elements, but they are noticeably less common. They can also be produced in the form of rechargeable batteries.
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Proprietary battery. Tools powered by its own battery (often built-in), which does not correspond to the standard sizes of replaceable elements. Such batteries can have a high capacity and power and are often more convenient than replaceable elements. In addition, they are usually supplied with the device, which eliminates the need to look for power supply yourself. The main disadvantage of this option is the impossibility of quick replacement in case of exhaustion of the charge — the battery will have to be cha
...rged, and this requires not only a power source, but also time. Theoretically, if the battery is removable, you can keep a spare charged battery ready, but in practice, spare elements are expensive, and it may be difficult to find them. For a number of technical reasons, such type of rower supply is rare, it can be found mainly in high-end models.
— 18650. The name of these batteries comes from their dimensions: 18.6 x 65.2 mm, cylindrical in shape, they look like slightly enlarged AA, but have an operating voltage of about 3.7 V and a higher capacity. In addition, all elements of the 18650 type by definition are not disposable, but rechargeable batteries (lithium-ion type).
— C. Replaceable elements of standard size, cylindrical shape, with a nominal voltage of 1.5 V. In length, they practically do not differ from the AA described above, but they are much thicker, due to that they have a higher capacity. At the same time, this type of power supply is quite rare; this can be said about the batteries themselves as well.Max. operating hours
The longest possible time of continuous operation of the metal detector without changing or recharging the batteries. Usually, some “perfect” time is indicated for the most optimal mode: constant stable operation of the coil without unnecessary energy consumption for sound signals, display indications and other additional functions, fully charged batteries or high-quality replaceable batteries, etc. Therefore, the actual time of continuous operation is likely to be somewhat less (how much depends on the features of the work). Nevertheless, this parameter describes well the battery life of the metal detector and allows you to evaluate its suitability for work "in isolation from civilization" (as well as the estimated number of spare batteries that may be needed for a complete survey of the desired territory).
Additionally included
Additional accessories and parts included with the metal detector. These can be devices for protection and ease of carrying in the working position or during transportation — belts, bags, cases, rain covers for the control unit; special equipment required for work — for example, a grounding rod for models with the RF operating principle; and other additional equipment. The presence of batteries and a charger for them in this paragraph is indicated only if the device uses replaceable elements (see "Power"), because cordless metal detectors are by default equipped with a battery and “charging”, and there is no need to specify this. Also, this paragraph does not cover spare replacement coils — their presence or absence characterizes the “Number of coils” paragraph.
Shaft length
The length of a metal detector rod is usually indicated by the distance from the coil to the upper end of the rod (where the armrest is located, if any). The higher the height of the operator, the longer the boom must be so that he can hold the coil above the ground without bending over (or not bending too much). In most models, the length lies in the range from 120 to 145 cm — for most adults this is quite a suitable value. Note that the rods can be adjustable (telescopic) — to adjust for growth.