The manufacturer positions the Terra-N metal detector as a device with an optimal price-quality ratio, designed for beginner treasure hunters. Low weight, reasonable price, ease of setup and high sensitivity have made the device really popular.
About the device
The Terra-N metal detector is used to search for metal objects in soils that do not conduct electric current. The device uses digital signal processing from the sensor, providing stability and high sensitivity. Data is analyzed using a high-frequency microcontroller, which allows you to quickly process the signal and display information on the panel in real time. Thanks to the use of a moisture-proof housing, the device can be operated in difficult conditions, without doubting its reliability.
The device has an unlimited resource, since its design does not contain parts with a limited operating time. The main advantage of the device is ease of use and increased detection depth. For example, the Terra-N metal coin is located at a depth of up to 25 cm, and the car - up to 2 m. The adaptation function for soil characteristics is available, which reduces the number of false positives by an order of magnitude. The characteristics of the Terra-N metal detector allow it to be used at temperatures from -25 to +80 degrees.
Work with the device
1. Adjustment of sensitivity. By changing this parameter, you can adjust the depth of the search. When working with metal-containing soil that causes background noise, it is recommended to lower the sensitivity until the noise disappears. When searching in unfamiliar areas, the sensitivity should be set to the minimum level, and then, in the absence of interference, gradually increase.
2. The choice of the threshold. The metal detector shows the size of the object, provided that the signal level exceeds a predetermined threshold. The threshold should be set based on the purpose of the search. The first level is chosen to search for small items: coins, chains, relics and other items that require high sensitivity. The second level is used for medium objects: pipelines, hiding places, as well as in the presence of a small number of metal entries in the soil. The third level is needed to search for scrap metal, as well as to eliminate interference from medium-sized objects.
Search Mode Selection
1. Dynamic search mode. In this mode, the metal detector will emit a signal only when the sensor moves over the search object. If there is no movement, the device will show a zero signal. This mode is designed for quick search. A two-tone sound signal is used here: a high tone sounds when non-ferrous metals are detected, low - if ferrous metal is found .
2. Static search mode. In this mode, the device will emit a signal throughout the entire time the subject is under the sensor. The sound volume will increase when approaching an object, and when moving away, it will decrease. This mode is used to accurately determine the size of the object and its location. When detecting an object, the device voices its characteristics using a 30-tone sound scale: low tone corresponds to ferrous metals, high tone to non-ferrous metals. The signal level is directly proportional to the size of the object.
Battery charge
If the battery voltage drops below 7.5 V, replace the battery. With a low charge, operation with the device is possible, but its sensitivity will be significantly lower.
Search Technique
It is recommended to hold the device in hand so that the user is most comfortable. The sensor coil should be moved in arcuate movements, with the next swing moving half the coil forward. This technique is called scanning. The coil must be held at a constant height for a stable detection depth. For quick searches, choose dynamic mode. The coil is allowed to be carried out on grass or soil, this does not affect the quality. Scanning should be carried out at a speed of up to 1 m / s. When a metal object is detected, the device emits a sound signal, and the size of the object is displayed on the indicator.
Positioning
If you need to accurately determine the position of the object, it is recommended to use the static search function. In this case, the coil of the device is moved by the technique of the cross. The sensor is moved first from left to right, and then back and forth, trying to find the point of greatest deviation of the signal. By the same principle, one should search for an item in the dynamic search mode. The device will make a sound if the object is located exactly under the sensor. The search process is simplified at a low scanning speed.
Instrument circuit
The electrical board of the device has the form shown in the figures below.
As you can see, the circuit of the Terra-N metal detector, in addition to small elements, contains only a processor and a field effect transistor. According to experienced amateur electronics engineers, this is disastrously small. The list of components proposed by the manufacturer characterizes the device as a low-quality device, since it cannot provide the proper sensitivity and search accuracy characteristics. Some forum enthusiasts are asked to provide firmware for the microcontroller, but more experienced colleagues advise not to repeat the design of the device, since its practicality is rather doubtful.
User reviews
Reviews about the Fragma Terra-N metal detector are quite contradictory. Usually the deciding factor when buying a device is its price. The Terra-N metal detector costs about 6,000 rubles, which makes it affordable even for people with a limited budget. The quality of the device at the same time leaves much to be desired. Judging by user reviews, for the same money you can buy a homemade device with much better characteristics or a used device of a popular brand.
Reviews about the price of the Terra-N metal detector, as a rule, end with people regretting the wasted money. Some recommend throwing away a useless device, others recommend breaking it against a birch, while others show prudence with advice to give the device to a child. According to real people who bought a metal detector, using it is comfortable to search only for scrap. The search for coins and valuables usually ends in a fiasco and a spoiled mood. Unsuccessful treasure hunters then buy time-tested devices and report on a completely different level of scan quality. The device is not recommended even for beginner metal detectors, as it can discourage the process as a whole. Knowledgeable people give advice to save up some money and buy a decent device, or pay attention to the devices that were in use.