|
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese|
ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Metal detector controls. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / metal detectors Any metal detector has certain controls - knobs, buttons, switches, etc. The simplest devices are equipped with only one handle. More complex ones can have up to a dozen different knobs and buttons. The purpose of these controls is briefly described below.
Threshold knob This knob regulates one of the most important functions of the metal detector - the sound threshold, or the optimal level of the sound signal necessary to achieve the highest sensitivity when the metal detector is in the all-metal search mode with ground balance. The process of setting the threshold is described in detail in the instructions supplied with the devices, but in any case, the threshold sound signal should be minimal, but distinguishable by your hearing. For most modern dynamic metal detectors, this setting occurs automatically, and when working in the discrimination mode, some models search without a threshold background (the so-called silent search), which creates a certain comfort during operation. Other devices require threshold adjustment in Discriminate mode as well. Some instruments have a switch, and you can choose between automatic or manual threshold adjustment, which is necessary when working on ground with rapidly changing mineralization, typical, for example, when searching for gold nuggets. Ground balance knob This knob is used to reduce the masking effect of iron minerals on metal objects in All Metal Search and Discriminate Modes. If the tuning is done incorrectly, then the signal from deep objects of small size will be inaudible against the background of the signal from the soil minerals. Some metal detectors have a constant, factory-set ground balance with an average mineral content. Such instruments do not have a ground balance knob. More expensive models have an automatic pound offset that continuously monitors the pound minerals and continuously tunes to give optimal depth of search, which is especially useful when working in areas with frequently changing mineralization. Discrimination knob Discrimination is the ability of a metal detector not to give an audible signal to unwanted objects - nails, corks, foil, beer can tabs, etc. If the discrimination level is set too high, then you will not hear a signal from the desired objects either. Some devices have two discrimination knobs and a switch that allows you to turn on additional discrimination during the search. The same effect is achieved in devices with a single knob, when you scan an object first at one level of discrimination, and then, turning the knob, check it at a different, higher level of discrimination. Thus, devices with two handles and a switch simply save time in the search process and allow you to work faster. Selective Discrimination Handle Unlike conventional discrimination, where by turning the knob, more and more electrically conductive objects are detuned, with selective discrimination, you can detune only from a certain object or group of objects, and the discrimination zone can be narrowed or expanded, as well as moved along the discrimination scale. Moreover, with the help of a switch, these objects can either be ignored or, conversely, accepted. In the latter case, all objects that do not fall into this zone will be ignored. In devices with a microprocessor, the selective discrimination zone can be observed on the display screen and adjusted as you wish. In this case, several such zones can be set, and objects falling into these zones can be ignored or received with great accuracy. For example, you can set up a metal detector in such a way that it will only find silver coins. It should be noted that with any discrimination, errors are possible due to changes in the mineralization of the soil, the depth of the object, the degree of its oxidation, i.e. change in the electrical conductivity of the object compared to the standard. However, in general, both types of discrimination speed up the search process, especially for small objects such as coins and jewelry. Sensitivity knob This knob adjusts the gain of the secondary signal. In addition, it can reduce the effect of electrical noise from high voltage lines and transmission stations. Unfortunately, the meaning of this adjustment is often misunderstood. Many operators assume that the higher the sensitivity is set, the deeper they will find objects. In reality, this is not the case, especially when working on soils with high mineralization, when it is possible to find deep objects only by lowering the sensitivity. Expensive models of metal detectors usually have two sensitivity knobs - one for the static mode of searching for all metals, the other for searching in the dynamic mode of discrimination. Visual object identification With the advent of dynamic type metal detectors, it became possible to identify an object, or rather, the identification of the metal from which the object is made. For earlier instruments, this was a dial indicator with a calibrated scale. Modern devices use LCD displays. In both cases, objects are identified based on measurements of their electrical conductive properties and phase shift. The big advantage of this display of information about the object is that it is independent of discrimination. For example, you have set a discrimination level that ignores nails, corks, and can tabs. At the same time, you no longer hear the audio signal from these objects, which increases your ability to distinguish weak signals from valuable objects that are close in electrical conductivity to the objects being discriminated. At the same time, by looking at the pointer of the device or by moving the cursor on the display screen, you can observe that there is an object under the coil, which, for example, can be a thin gold ring or a gold chain. Such an object must be checked by digging it out. Until now, a metal detector has not been invented that would give an image of an object on the screen, but such devices will certainly appear in the future. Sound object identification In parallel with the development of visual identification methods, sound identification methods were developed, which made it possible to identify it with varying degrees of probability by the sound of the signal emitted by the device when an object was detected. The most expensive modern devices may have several beeps - a variable frequency tone, a two- and three-tone tone, and a telephone ring type tone. A signal with a variable frequency, with some skill, allows you to identify an object without digging it out, since the frequency of the sound emitted by the device in this case depends on the electrical conductivity of the object: as it increases, the sound frequency also increases. Two-tone sound identification is used in devices with selective discrimination. Objects located to the left of the discrimination zone give a low tone, to the right of the zone - a high tone. Objects entering the zone give a two-tone signal. In devices with a three-tone signal (low, medium and high tone), the identification of the object is based on the nature of the signal, since the latter depends on the electrical conductivity of the object. This is convenient, since you do not have to constantly be distracted by the screen. Some metal detectors, when detecting a large object, emit a signal similar to a telephone ring. When searching for coins, such a signal is very useful, as it saves time. Measuring the depth of an object Metal detectors with visual identification are able to measure the depth of objects the size of a coin. Since the device can detect a coin at a depth of up to 30 cm, the scale is also graduated to the same depth. Unfortunately, depth measurement results are often erroneous for objects other than coins. So, a lead shot on the surface of a pound reads a coin at a depth of 15 cm, or a relatively large object at a depth of 60-80 cm can be identified as a coin at a depth of 20-25 cm. With experience, you will learn to determine the depth of objects quite accurately. Volume control Most metal detectors do not have a volume control. Therefore, the use of conventional headphones when working with such devices is undesirable, since your ear is subjected to significant stress when detecting objects. It is more convenient to work with headphones that have a volume control. If the metal detector has a volume control and your headphones also have a volume control, it is recommended to set the detector to maximum volume and adjust the headphone volume so that the signal from a large object is acceptable to your hearing. Battery Test As a rule, the battery status is checked automatically when the metal detector is turned on for the first time. At the same time, within 3-5 seconds. an audible signal is heard, by the strength of which they judge the condition of the batteries. For some metal detectors with arrow indicators, the state of the batteries is automatically estimated by the position of the arrow when the device is turned on for the first time or when a certain button is pressed. Typically, "rested" batteries have an increased voltage. Therefore, more accurately, the condition of the batteries can only be judged after 15 minutes. work with the device. For metal detectors with a liquid crystal display, the status of the batteries is continuously displayed on the screen graphically in the form of a series of segments, the number of which decreases as the batteries are discharged, or directly in the form of voltage in volts. Some devices, when the batteries are significantly discharged, emit a light or sound signal warning that the voltage has dropped and the batteries will last only one hour of operation. Operating frequency switch This switch allows you to change the operating frequency of the metal detector in order to reduce the influence of the same devices operating a few meters away from you. This is especially important if you take part in search competitions, where you are often surrounded by several people who have the same device model as you. It should be noted that a significant frequency deviation from the norm can reduce the depth of the metal detector. Pinpoint button Although the term "pinpointing" is absent in the Russian language, nevertheless, its use in the description of metal detectors is more appropriate than the phrase "detection of the exact location of an object using electronics", which it actually means. When this button is pressed, the object beeps when it is exactly under the center of the coil. This is due to a short-term imbalance of the threshold, due to which the electromagnetic field becomes less sensitive to the object. Some of the modern metal detectors in pinpointing mode use a special sound generator that changes the frequency of the signal as the center of the coil approaches the object. Unfortunately, when a large object is detected, the search for its exact location is accompanied by unpleasant howls, reminiscent of the roar of a siren. The advantage of this function of the device is a clear distinction between several objects located close enough to each other. Author: Bulgak L.V.
Artificial leather for touch emulation
15.04.2024 Petgugu Global cat litter
15.04.2024 The attractiveness of caring men
14.04.2024
▪ A quantum computer that does not use qubits ▪ Apple TV sales may begin in late 2012 ▪ Electric car as a backup power source in the house ▪ Hereditary obesity is not always determined by genes
▪ section of the site Riddles for adults and children. Article selection ▪ article Reliable, profitable, convenient! Popular expression ▪ article When was bread first baked? Detailed answer ▪ article Working with a lawn mower. Standard instruction on labor protection ▪ article Golden varnishes. Simple recipes and tips ▪ article Magic envelope. Focus Secret
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua |
See other articles Section 
Latest news of science and technology, new electronics:
All languages of this page