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Metal detector

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silver treasure. The French law on metal detecting is ambiguous because it refers only to the objective pursued by the user of a metal detector. The first law to regulate the use of metal detectors was Law No. 89–900 of 18 December 1989. This last is resumed without any change in Article L. 542–1 of the code of the heritage, which states that "no person may use the equipment for the detection of metal objects, for the purpose of research monuments and items of interest prehistory, history, art and archeology without having previously obtained an administrative authorization issued based on the applicant's qualification and the nature and method of research."
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magnetized the ground with a relatively powerful, momentary current through a search coil. In the absence of metal, the field decayed at a uniform rate, and the time it took to fall to zero volts could be accurately measured. However, if metal was present when the machine fired, a small eddy current would be induced in the metal, and the time for sensed current decay would be increased. These time differences were minute, but the improvement in electronics made it possible to measure them accurately and identify the presence of metal at a reasonable distance. These new machines had one major advantage: they were mostly impervious to the effects of
461:"The new law does not prohibit the use of metal detectors but only regulates the use. If the purpose of such use is the search for archaeological remains, prior authorization is required from my services. Apart from this case, the law ask to be reported to the appropriate authorities an accidental discovery of archaeological remains." The entire letter of Jack Lang was published in 1990 in a French metal detection magazine, and then, to be visible on the internet, scanned with permission of the author of the magazine on a French metal detection website. 507:, the Crown has claim over any object of any material value where the original owner cannot be traced. There is also no 300 year limit to Scottish finds. Any artifact found, whether by metal detector survey or from an archaeological excavation, must be reported to the Crown through the Treasure Trove Advisory Panel at the National Museums of Scotland. The panel then determines what will happen to the artifacts. Reporting is not voluntary, and failure to report the discovery of historic artifacts is a criminal offence in Scotland. 191:
should be possible to design a machine which would detect metal using a search coil resonating at a radio frequency. In 1925 he applied for, and was granted, the first patent for an electronic metal detector. Although Gerhard Fischer was the first person granted a patent for an electronic metal detector, the first to apply was Shirl Herr, a businessman from Crawfordsville, Indiana. His application for a hand-held Hidden-Metal Detector was filed in February 1924, but not patented until July 1928. Herr assisted Italian leader
129: 769: 412:. However archaeologists oppose the use of metal detectors by "artifact seekers" or "site looters" whose activities disrupt archaeological sites. The problem with use of metal detectors in archaeological sites or hobbyist who find objects of archeological interest is that the context that the object was found in is lost and no detailed survey of its surroundings is made. Outside of known sites the significance of objects may not be apparent to a metal detector hobbyist. 163:. After much experimenting the best bullet detection range he achieved was only 2 inches (5 centimeters). He then used his own earlier discovery, the partially overlapping 2-coil induction balance, and the detection range increased to 5 inches (12 centimeters). But the attempt was still unsuccessful because the metal coil spring bed Garfield was lying on confused the detector. Bell's 2-coil induction balance would go on to evolve into the popular double D coil. 525: 265:) machine. With the invention and development of the transistor in the 1950s and 1960s, metal detector manufacturers and designers made smaller, lighter machines with improved circuitry, running on small battery packs. Companies sprang up all over the United States and Britain to supply the growing demand. Beat Frequency Induction requires movement of the detector coil; akin to how swinging a conductor near a magnet induces an electric current. 840: 656: 42:. Metal detectors are useful for finding metal objects on the surface, underground, and under water. A metal detector consists of a control box, an adjustable shaft, and a variable-shaped pickup coil. When the coil nears metal, the control box signals its presence with a tone, light, or needle movement. Signal intensity typically increases with proximity. A common type are stationary "walk through" metal detectors used at access points in 1045: 940: 559: 144:
induced a voltage in the secondary coils. When the secondary coils were wired in opposition, the induced voltages cancelled as confirmed by the Professor holding the ends of the secondary coils. When a piece of metal was placed inside one glass tube the Professor received a shock. This then was the first magnetic induction metal detector, and the first pulse induction metal detector.
152:"electric sonometer". Hughes did much to popularize the induction balance, quickly leading to practical devices that could identify counterfeit coins. In 1880 Mr. J. Munro, C.E. suggested the use of the 4-coil induction balance for metal prospecting. Hughes's coaxial 3-coil induction balance would also see use in metal detecting. 875:
systems. In 1995 systems such as the Metor 200 appeared with the ability to indicate the approximate height of the metal object above the ground, enabling security personnel to more rapidly locate the source of the signal. Smaller hand held metal detectors are also used to locate a metal object on a person more precisely.
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was wounded in the foot. It was difficult to distinguish between bullet, bone, and cartilage. So Professor Favre of Marseilles quickly built a simple probe that was inserted into the track of the bullet. It had 2 sharp points connected to a battery and a bell. Contact with metal completed the circuit
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Even with discriminators, it was still a challenge to avoid undesirable metals, because some of them have similar phase responses (e.g. tinfoil and gold), particularly in alloy form. Thus, improperly tuning out certain metals increased the risk of passing over a valuable find. Another disadvantage of
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transmitter, the other as a receiver; in some cases these can be tuned to between 3 and 100 kHz. When metal is in their vicinity, a signal is detected owing to eddy currents induced in the metal. What allowed detectors to discriminate between metals was the fact that every metal has a different
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The metal detecting community and professional archaeologists have different ideas related to the recovery and preservation of historic finds and locations. Archaeologists claim that detector hobbyists take an artifact-centric approach, removing these from their context resulting in a permanent loss
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General metal detecting is very similar to coin shooting except the user is after any type of historical artifact. Detectorists may be dedicated to preserving historical artifacts, and often have considerable expertise. Coins, bullets, buttons, axe heads, and buckles are just a few of the items that
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Outside the research of archaeological objects, using a metal detector does not require specific authorization, except that of the owner of the land. Asked about Law No. 89–900 of 18 December 1989 by a member of parliament, Jack Lang, Minister of Culture at the time, replied by letter the following:
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published his experiments with the 4-coil induction balance. He used his own recent invention the microphone and a ticking clock to generate regular pulses and a telephone receiver as detector. To measure the strength of the signals he invented a coaxial 3-coil induction balance which he called the
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The sale of metal detectors is allowed in France. The first use of metal detectors in France which led to archaeological discoveries occurred in 1958: people living in the city of Graincourt-lès-Havrincourt who were seeking copper from World War I bombshell with military mine detector found a Roman
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when exposed to alternating current; longer waves (low frequency) penetrate ground deeper, and select for high-conductivity targets like silver, and copper; than shorter waves (higher frequency) which, while less ground penetrating, select for low-conductivity targets like iron. Unfortunately, high
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On December 16, 1881, Captain Charles Ambrose McEvoy applied for British Patent No. 5518, Apparatus for Searching for Submerged Torpedoes, &c., which was granted Jun 16 1882. His US269439 patent application of Jul 12 1882 was granted Dec 19 1882. It was a 4-coil induction balance for detecting
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Due to eddy currents induced in the metal, a signal is detected when metal is present. The fact that every metal has a different phase response when exposed to alternating current allowed detectors to differentiate between metals. Longer waves (low frequency) penetrate the ground deeper and select
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by profession, began metal detecting as a pastime in the early 1960s. He tried a number of machines on the market but couldn't find one that could do what he needed. As a result, he started developing his own metal detector. He was able to develop a system that removed oscillator drift, as well as
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Company and Western Air Express to establish airborne direction finding equipment in the late 1920s. He received some of the first patents in the area of radio-based airborne direction finding. He came across some unusual errors in the course of his work; once he figured out what was wrong, he had
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The sale of metal detectors is allowed in the United States. People can use metal detectors in public places (parks, beaches, etc.) and on private property with the permission of the owner of the site. In the United States, cooperation between archeologists hunting for the location of colonial-era
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had developed a system of radio direction-finding, which was to be used for accurate navigation. The system worked extremely well, but Fischer noticed there were anomalies in areas where the terrain contained ore-bearing rocks. He reasoned that if a radio beam could be distorted by metal, then it
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The coil configuration is such that it creates an opening whereby the product (food, plastics, pharmaceuticals, etc.) passes through the coils. This opening or aperture allows the product to enter and exit through the three-coil system, producing an equal but mirrored signal on the two receiving
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published an invention he called the "differential inductor". It was a 4-coil induction balance, with 2 glass tubes each having 2 well-insulated copper wire solenoids wound around them. Charged Leyden jars (high-voltage capacitors) were discharged through the 2 primary coils; this current surge
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Coil designers also tried out innovative designs. The original induction balance coil system consisted of two identical coils placed on top of one another. Compass Electronics produced a new design: two coils in a D shape, mounted back-to-back to form a circle. The system was widely used in the
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evolved in the form of the rectangular gantry now standard in airports. In common with the developments in other uses of metal detectors both alternating current and pulse systems are used, and the design of the coils and the electronics has moved forward to improve the discrimination of these
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governs whether or not items that have been discovered are defined as treasure. Finders of items that the Act defines as treasure must report their finds to the local coroner. If they discover items which are not defined as treasure but that are of cultural or historical interest, finders can
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in the ground. This gave greater depth, but was a non-discriminate mode. It worked best at lower frequencies than those used before, and frequencies of 3 to 20 kHz were found to produce the best results. Many detectors in the 1970s had a switch which enabled the user to switch between the
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At the same time, developers were looking at using a different technique in metal detection called pulse induction. Unlike the beat frequency oscillator or the induction balance machines, which both used a uniform alternating current at a low frequency, the pulse induction (PI) machine simply
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Fisher received the patent for the first portable electronic metal detector in 1925. In 1931, he marketed his first Fisher device to the general public, and he established a famous Fisher Labs company that started to manufacture and develop hand-held metal detectors and sell it commercially.
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Current practice at garment or apparel industry plants is to apply metal detecting after the garments are completely sewn and before garments are packed to check whether there is any metal contamination (needle, broken needle, etc.) in the garments. This needs to be done for safety reasons.
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Modern top models are fully computerized, using integrated circuit technology to allow the user to set sensitivity, discrimination, track speed, threshold volume, notch filters, etc., and hold these parameters in memory for future use. Compared to just a decade ago, detectors are lighter,
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Despite the fact that Fisher was the first to receive a patent for an electronic metal detector, he was only one of many who improved and mastered the device. Charles Garrett, the founder of Garrett Metal Detectors, was another key figure in the creation of today's metal detectors.
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discriminate mode and the non-discriminate mode. Later developments switched electronically between both modes. The development of the induction balance detector would ultimately result in the motion detector, which constantly checked and balanced the background mineralization.
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coils. The search coil works as sensing probe and must be moved over the ground to detect potential metal targets buried underground. When the search coil detects metal objects, the device gives an audible signal via speaker or earphone. In most units, the feedback is an
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Humanitarian demining aims to clear all landmines to a certain depth and make the land secure for human use. Landmine detection techniques have been studied in various forms. Detection of mines can be done by a specially designed metal detector tuned to detect mines and
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Many manufacturers of these new devices brought their own ideas to the market. White's Electronics of Oregon began in the 1950s by building a machine called the Oremaster Geiger Counter. Another leader in detector technology was Charles Garrett, who pioneered the BFO
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coils. The resulting signals are summed together effectively nullifying each other. Fortress Technology innovated a new feature, that allows the coil structure of their BSH Model to ignore the effects of vibration, even when inspecting conductive products.
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Metal detectors are also used to search for discarded or lost, valuable man-made objects such as jewelry, mobile phones, cameras and other devices. Some metal detectors are waterproof, to allow the user to search for submerged objects in areas of shallow
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significantly impacted the design of metal detectors as we know them today: lightweight, compact, easy-to-use, and deep-seeking systems. The invention of a tunable induction device was the most significant technological advancement in detectors. Two
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Jarvi, A, Leinonen, E, Thompson, M, and Valkonen K, Designing Modern Walk-through Metal Detectors, Access Security Screening: Challenges and Solutions, ASTM STP 1127 TP Tsacoumis Ed, American Society for Testing of Materials, Philadelphia 1992,
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developed a 4-coil induction balance to detect unexploded shells in farmland of former battlefields in France. Unusually both coil pairs were used for detection. The 1919 photo at the right is a later version of Gutton's detector.
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adapted mining metal detectors in the 1970s, still housed in a large cylindrical pipe, to make a commercial walk-through security detector. The development of these systems continued in a spin-off company and systems branded as
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The first metal detector was likely the simple electric conduction metal detector ca. 1830. Electric conduction was also used to locate metal ore bodies by measuring the conductivity between metal rods driven into the ground.
1168:, also known as mine removal, is the method of clearing a field of landmines. The aim of military operations is to clear a path through a minefield as quickly as possible, which is mostly accomplished using equipment like 489:, laws against metal detecting are very strict: it is illegal to use a detection device to search for archaeological objects anywhere within the State or its territorial seas without the prior written consent of the 1380:), particularly in alloy form. As a result, tuning out those metals incorrectly increased the chance of missing a valuable discovery. Discriminators also had the downside of lowering the sensitivity of the devices. 167:
submerged metallic torpedoes and iron ships and the like. Given the development time involved this may have been the earliest known device specifically constructed as a metal detector using magnetic induction.
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is hunting for lost coins or jewelry on a beach. Beach hunting can be as simple or as complicated as one wishes to make it. Many dedicated beach hunters also familiarize themselves with tide movements and
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When a metal contaminant is introduced into the product an unequal disturbance is created. That creates a very small electronic signal. After suitable amplification a mechanical device mounted to the
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Metal detectors are also used to detect foreign bodies in food, as well as steel reinforcement bars in concrete and pipes. The building industry uses them to find wires buried in walls or floors.
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As the creation and refinement of the device was a wartime military research operation, the knowledge that Kosacki created the first practical metal detector was kept secret for over 50 years.
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The industrial metal detector was developed by Bruce Kerr and David Hiscock in 1947. The founding company Goring Kerr pioneered the use and development of the first industrial metal detector.
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Contamination of food by metal shards from broken processing machinery during the manufacturing process is a major safety issue in the food industry. Most food processing equipment is made of
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are commonly found by relic hunters; in general the potential is far greater in Europe and Asia than in many other parts of the world. More valuable finds in Britain alone include the
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1970s, and both concentric and double D type (or widescan as they became known) had their fans. Another development was the invention of detectors which could cancel out the effect of
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The biggest technical change in detectors was the development of a tunable induction system. This system involved two coils that are electro-magnetically tuned. One coil acts as an
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developed a portable metal detector in 1925. His model was first marketed commercially in 1931; he was responsible for the first large-scale hand-held metal detector development.
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to operate and became more sensitive but still quite cumbersome. One of the early common uses of the first metal detectors, for example, was the detection of landmines and
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Coin shooting is specifically targeting coins. Some coin shooters conduct historical research to locate sites with potential to give up historical and collectible coins.
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system is signaled to remove the contaminated product from the production line. This process is completely automated and allows manufacturing to operate uninterrupted.
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by Fisher Labs in the 1930s; other companies like Garrett established and developed the metal detectors in terms of technology and features in the following decades.
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interference. This selectivity or discrimination allowed detectors to be developed that could selectively detect desirable metals, while ignoring undesirable ones.
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interference affects high frequency as well. This selectivity or discrimination allowed the development of detectors that can selectively detect desirable metals.
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The first metal detector proved inductance changes to be a practical metal detection technique, and it served as the prototype for all subsequent metal detectors.
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In 1926, two Leipzig, Germany scientists installed a walk-though enclosure at a factory, to ensure that employees were not exiting with prohibited metallic items.
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Metal detectors are widely used in archaeology with the first recorded use by military historian Don Rickey in 1958 who used one to detect the firing lines at
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soil; in some cases the heavy mineral content may even help the PI detector function better. Where a VLF detector is affected negatively by soil
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The first industrial metal detectors came out in the 1960s. They were used for finding minerals among other things. Metal detectors help find
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Graves M, Smith A, and Batchelor B 1998: Approaches to foreign body detection in foods, Trends in Food Science & Technology 9 21-27
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The difference between archaeology and looting, explained Brian Jones, Connecticut's state archaeologist, is the recording of context.
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Even with discriminators, avoiding undesirable metals was difficult because some of them have similar phase responses (for example,
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The basic principle of operation for the common industrial metal detector is based on a 3-coil design. This design utilizes an AM (
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Metal detecting clubs exist for hobbyists to learn from others, show off finds from their hunts and to learn more about the hobby.
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One particular advantage of using a pulse induction detector includes the ability to ignore the minerals contained within heavily
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In the 1960s, the first industrial metal detectors were produced, and they were widely used for mineral prospecting and other
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State-of-the-art metal detectors have further incorporated extensive wireless technologies for the earphones, connect to
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many special search coils that he patented, both of which effectively revolutionized metal detector design at the time.
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and rang the bell. In 1867 Mr. Sylvan de Wilde had a similar detector and an extractor also wired to a bell. In 1870
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initially used a 4-coil induction balance to attempt to locate a bullet lodged in the chest of American President
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led the United States in 1972 to adopt metal detector technology to screen airline passengers, initially using
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Connor, Melissa; Scott, Douglas D. (1 January 1998). "Metal Detector Use in Archaeology: An Introduction".
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locator technology to keep track of searching location and the location of items found. Some connect to
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metal detecting is legal provided that the landowner has granted permission and that the area is not a
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In 1892 George M. Hopkins described an orthogonal 2-coil induction balance for metal detecting.
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the foresight to apply the solution to a totally unrelated area, metal and mineral detection."
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was one of the first customers of Goring Kerr using their Metlokate metal detector to inspect
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Hobbyists often use their own metal detecting lingo when discussing the hobby with others.
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Outline of the Scientific Accomplishments of the Byrd Antarctic Expedition II, 1933-1935
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serve as evidence against allowing unsupervised metal detecting in historic locations.
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An early metal detector, in 1919, used to find un-exploded bombs in France after
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Alexander Graham Bell: The Life and Times of the Man Who Invented the Telephone
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before emigrating to the United States. When working as a research engineer in
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The Polish Contribution to The Ultimate Allied Victory in The Second World War
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The metal detectors were first invented and manufactured commercially in the
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to clear the minefields of the retreating Germans, and later used during the
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Fisher, the founder of Fisher Research Laboratory, was contracted by the
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The most common type of metal detector is a hand-held metal detector or
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Politics and conflicts in the metal detecting hobby in the United States
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There are various types of hobby activities involving metal detectors:
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discriminators was that they reduced the sensitivity of the machines.
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Exposing mines planted during the war or after the end of the war
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of historical information. Archaeological looting of places like
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deeper-seeking, use less battery power, and discriminate better.
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The modern development of the metal detector began in the 1920s.
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Electronic instrument which detects the presence of metal nearby
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that were originally designed for logging operations to detect
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The design invented by Kosacki was used extensively during the
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deal primarily with the United States and do not represent a
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tuned coils were used in this method. One coil serves as an
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Native American villages and hobbyists has been productive.
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in concrete and pipes and wires buried in walls and floors.
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Hand-held metal detectors can be used to search people for
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in a number of European countries following the First and
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Colin King (Editor), Jane's Mines and Mine Clearance,
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Initially these machines were huge and complex. After
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The simplest form of a metal detector consists of an
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that passes through a coil producing an alternating
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Unsourced material may be challenged and 968:. Unsourced material may be challenged and 709:gold, sold for ÂŁ3,285,000, the gold Celtic 372:Large portable metal detectors are used by 255: 2310:. New York: Harry N. Abrahms, Inc., 1997. 1962:"Archaeology and treasure | nidirect" 1640:: CS1 maint: location missing publisher ( 1601:, 1915 Nov 13, front cover & page 425. 1538:"APPARATUS FOR FINDING TORPEDOES, &c." 1482:Proceedings of the Royal Society of London 794:, or create a new section, as appropriate. 222:, who refined the design into a practical 123: 1730: 1208: 1093:Learn how and when to remove this message 988:Learn how and when to remove this message 810:Learn how and when to remove this message 643:Learn how and when to remove this message 2306:Grosvenor, Edwin S. and Wesson, Morgan. 2185: 1625: 1131:Metal detectors can be used for several 838: 654: 523: 127: 18: 1980:"The Law on Metal Detecting in Ireland" 195:in recovering items remaining from the 2338: 1550:"McEvoy's Electric Submarine Detector" 1285:purposes. De-mining (the detection of 480: 432:(SSSI), or covered by elements of the 311:frequency is also sensitive to ground 218:, Scotland, during the early years of 181: 2046:"Finding Jewelry with Metal Detector" 1160: 834: 285:devices. Some also utilize built in 2206:"Company | Fortress Technology" 2167:from the original on 23 October 2016 1126: 1071:adding citations to reliable sources 1038: 966:adding citations to reliable sources 933: 929: 762: 681:is looking for valuable metals like 581:adding citations to reliable sources 552: 536:A man metal detecting on a beach in 448:and the UK Detector Finds Database. 415: 38:that detects the nearby presence of 2029:Dave McCracken (23 November 2011). 1740:Tyler J. Kelley (16 January 2017). 1610: 1353:for high conductivity targets like 1317:are just some of the applications. 1142:Detecting dangerous explosives and 464: 430:site of special scientific interest 322: 13: 1259: 1213: 659:This 156-troy-ounce (4.9 kg) 380:to locate metallic items, such as 336: 14: 2372: 2108:"The History of Airport Security" 2060:"Metal Detecting Jargon Glossary" 2044:Scott Clark (30 September 2012). 1655:Croll, Mike; Cooper, Leo (1998). 1630:. Worthing, England. p. 221. 1452:, 1841 series 2 vol 54, page 305. 1276: 501:Under the Scots law principle of 296: 2261:"A new method of probing wounds" 2091:"The Radio Watchman at the Gate" 1349:ranging from 3 to 100 kHz. 1043: 938: 767: 557: 510: 96:. They also detect weapons like 2270: 2254: 2245:"An ingenious bullet detector " 2238: 2226: 2212: 2198: 2186:Pehanich, Mike (16 July 2007). 2179: 2149: 2128: 2118: 2100: 2097:, April 1926, pages 1408, 1493. 2084: 2070: 2052: 2037: 2022: 2004: 1990: 1972: 1954: 1936: 1918: 1904: 1864: 1829: 1807: 1785: 1763: 1687: 1673: 1648: 1619: 1604: 1588: 1572: 829:Petersburg National Battlefield 737:and thousands of smaller finds. 568:needs additional citations for 444:voluntarily report them to the 233:when 500 units were shipped to 2093:, April 1926, Dr. K. Schuett, 1559: 1543: 1531: 1517: 1501: 1487: 1484:, 1879 May 15 vol 29, page 56. 1471: 1455: 1439: 434:Countryside Stewardship Scheme 403: 268: 1: 2299: 2112:savvytraveler.publicradio.org 1748:. No. The New York Times 1450:Annalen der Physik und Chemie 1390:List of metal detecting finds 1187: 519: 2136:"Industrial metal detectors" 1585:, 1915 July 26, pages 71-73. 400:buried beneath the surface. 7: 2016:www.metaldetectingworld.com 1540:, C. A. McEvoy, 1882 Dec 19 1427:Portable Antiquities Scheme 1383: 1324:Discriminators and circuits 1146:dangerous to people's lives 1034: 790:, discuss the issue on the 496: 446:Portable Antiquities Scheme 231:Second Battle of El Alamein 10: 2379: 2188:"Detecting Foreign Matter" 1984:National Museum of Ireland 1681:"How Metal Detectors Work" 1626:Modelski, Tadeusz (1986). 1480:, Professor D. E. Hughes, 879:Industrial metal detectors 543: 475:Department for Communities 426:Scheduled Ancient Monument 1998:"Treasure Trove Scotland" 1856:Cite uses generic title ( 1659:. Pen & Sword Books. 845:Berlin Schönefeld Airport 451: 263:beat frequency oscillator 239:Allied invasion of Sicily 199:galleys at the bottom of 104:, which is important for 2157:"History of Goring Kerr" 1657:The History of Landmines 1556:, 1882 Aug 18, page 154. 1432: 1365:. Unfortunately, ground 1196:In 1862 Italian General 256:Beat frequency induction 243:Allied invasion of Italy 235:Field Marshal Montgomery 2361:19th-century inventions 2233:Morning Herald (London) 1569:, 1892 Aug 20, page 114 1514:, 1880 Jan 17, page 103 1468:, 1853 vol I, page 424. 1224:Gerhard Fisher studied 392:and other accessories, 367: 208:JĂłzef StanisĹ‚aw Kosacki 124:History and development 2267:, 1870 Jan 19, page 45 1892:Cite journal requires 1871:"Le Prospecteur" (5). 1696:Historical Archaeology 1464:, Auguste de la Rive, 1209:Technology development 1024:or digital indicator. 865:. The Finnish company 847: 668: 541: 136: 118:steel reinforcing bars 27: 2282:www.metaldetector.com 2251:, 1867 July, page 457 2235:, 1862 Nov 13, page 5 1230:University of Dresden 1004:) are used to locate 872:Metor Metal Detectors 842: 727:Crosby Garrett Helmet 719:West Bagborough Hoard 658: 535: 157:Alexander Graham Bell 141:Heinrich Wilhelm Dove 131: 114:construction industry 56:psychiatric hospitals 22: 2012:"Coin Shooting Tips" 1968:. November 12, 2015. 1932:. November 12, 2019. 1339:electro-magnetically 1289:), the detection of 1067:improve this section 962:improve this section 788:improve this section 577:improve this article 396:, and other various 364:, a PI unit is not. 247:Invasion of Normandy 224:Polish mine detector 62:on a person's body. 58:to detect concealed 2222:. 23 November 2011. 2208:. 10 November 2016. 1966:www.nidirect.gov.uk 1950:. November 8, 2019. 1914:. 30 December 2021. 1611:Poulter, Thomas C. 1599:Scientific American 1567:Scientific American 1334:wireless technology 1328:The development of 1270:electrical engineer 909:amplitude modulated 855:aircraft hijackings 843:Metal detectors at 723:Milton Keynes Hoard 703:Staffordshire Hoard 487:Republic of Ireland 481:Republic of Ireland 182:Modern developments 149:David Edward Hughes 71:alternating current 2346:1881 introductions 2192:foodprocessing.com 1746:The New York Times 1708:10.1007/BF03374273 1408:Television series) 1198:Giuseppe Garibaldi 1161:War mine detection 1122:Second World Wars. 1006:reinforcement bars 848: 835:Security screening 669: 542: 197:Emperor Caligula's 173:In 1915 Professor 139:In 1841 Professor 137: 28: 1815:"Report Treasure" 1666:978-0-85052-628-8 1301:(particularly in 1249:Federal Telegraph 1127:Uses and benefits 1103: 1102: 1095: 998: 997: 990: 930:Civil engineering 898:Mars Incorporated 820: 819: 812: 653: 652: 645: 627: 533: 441:Treasure Act 1996 422:England and Wales 416:England and Wales 81:will be induced ( 2368: 2293: 2292: 2290: 2288: 2274: 2268: 2265:American artisan 2258: 2252: 2242: 2236: 2230: 2224: 2223: 2216: 2210: 2209: 2202: 2196: 2195: 2183: 2177: 2176: 2174: 2172: 2153: 2147: 2146: 2144: 2142: 2132: 2126: 2122: 2116: 2115: 2104: 2098: 2088: 2082: 2081: 2074: 2068: 2067: 2056: 2050: 2049: 2041: 2035: 2034: 2026: 2020: 2019: 2008: 2002: 2001: 1994: 1988: 1987: 1976: 1970: 1969: 1958: 1952: 1951: 1940: 1934: 1933: 1922: 1916: 1915: 1908: 1902: 1901: 1895: 1890: 1888: 1880: 1868: 1862: 1861: 1854: 1852: 1844: 1833: 1827: 1826: 1824: 1822: 1811: 1805: 1804: 1802: 1800: 1789: 1783: 1782: 1780: 1778: 1767: 1761: 1760: 1755: 1753: 1737: 1728: 1727: 1691: 1685: 1684: 1677: 1671: 1670: 1652: 1646: 1645: 1639: 1631: 1623: 1617: 1616: 1608: 1602: 1592: 1586: 1581:, M. C. Gutton, 1576: 1570: 1563: 1557: 1547: 1541: 1535: 1529: 1528: 1521: 1515: 1510:, Mr. J. Munro, 1505: 1499: 1498: 1491: 1485: 1475: 1469: 1459: 1453: 1443: 1412:Inductive sensor 1315:treasure hunting 1303:airport security 1118:unexploded bombs 1098: 1091: 1087: 1084: 1078: 1047: 1039: 993: 986: 982: 979: 973: 942: 934: 815: 808: 804: 801: 795: 771: 770: 763: 648: 641: 637: 634: 628: 626: 592:"Metal detector" 585: 561: 553: 534: 471:Northern Ireland 465:Northern Ireland 378:treasure hunters 323:New coil designs 193:Benito Mussolini 110:treasure hunting 106:airport security 83:inductive sensor 2378: 2377: 2371: 2370: 2369: 2367: 2366: 2365: 2356:Metal detecting 2336: 2335: 2334: 2302: 2297: 2296: 2286: 2284: 2276: 2275: 2271: 2259: 2255: 2243: 2239: 2231: 2227: 2218: 2217: 2213: 2204: 2203: 2199: 2184: 2180: 2170: 2168: 2163:. 27 May 2012. 2155: 2154: 2150: 2140: 2138: 2134: 2133: 2129: 2123: 2119: 2106: 2105: 2101: 2089: 2085: 2076: 2075: 2071: 2058: 2057: 2053: 2042: 2038: 2027: 2023: 2010: 2009: 2005: 1996: 1995: 1991: 1978: 1977: 1973: 1960: 1959: 1955: 1942: 1941: 1937: 1924: 1923: 1919: 1910: 1909: 1905: 1893: 1891: 1882: 1881: 1870: 1869: 1865: 1855: 1846: 1845: 1835: 1834: 1830: 1820: 1818: 1817:. HM Government 1813: 1812: 1808: 1798: 1796: 1791: 1790: 1786: 1776: 1774: 1769: 1768: 1764: 1751: 1749: 1738: 1731: 1692: 1688: 1679: 1678: 1674: 1667: 1653: 1649: 1633: 1632: 1624: 1620: 1609: 1605: 1593: 1589: 1577: 1573: 1564: 1560: 1548: 1544: 1536: 1532: 1523: 1522: 1518: 1512:The Electrician 1506: 1502: 1493: 1492: 1488: 1476: 1472: 1460: 1456: 1444: 1440: 1435: 1386: 1326: 1279: 1262: 1260:Charles Garrett 1242:Albert Einstein 1219:Gerhard Fischer 1216: 1214:Gerhard Fischer 1211: 1190: 1163: 1129: 1099: 1088: 1082: 1079: 1064: 1048: 1037: 994: 983: 977: 974: 959: 943: 932: 887:stainless steel 881: 863:spikes in trees 837: 816: 805: 799: 796: 785: 772: 768: 761: 663:, known as the 649: 638: 632: 629: 586: 584: 574: 562: 551: 524: 522: 513: 499: 483: 467: 454: 418: 410:Little Big Horn 406: 390:clothes buttons 370: 339: 337:Pulse induction 325: 299: 271: 258: 188:Gerhard Fischer 184: 126: 17: 12: 11: 5: 2376: 2375: 2364: 2363: 2358: 2353: 2348: 2333: 2332: 2329: 2319: 2303: 2301: 2298: 2295: 2294: 2269: 2253: 2237: 2225: 2211: 2197: 2178: 2148: 2127: 2117: 2099: 2083: 2069: 2051: 2036: 2021: 2003: 1989: 1971: 1953: 1935: 1917: 1903: 1894:|journal= 1863: 1828: 1806: 1784: 1762: 1729: 1686: 1683:. 23 May 2001. 1672: 1665: 1647: 1618: 1603: 1587: 1583:Comptes Rendus 1571: 1558: 1542: 1530: 1516: 1500: 1486: 1470: 1454: 1448:, H. W. Dove, 1437: 1436: 1434: 1431: 1430: 1429: 1424: 1422:Magnet fishing 1419: 1417:Induction loop 1414: 1409: 1397: 1392: 1385: 1382: 1367:mineralization 1343:RF transmitter 1325: 1322: 1278: 1277:To present day 1275: 1261: 1258: 1238:aircraft radio 1215: 1212: 1210: 1207: 1203:Gustave TrouvĂ© 1189: 1186: 1162: 1159: 1158: 1157: 1147: 1140: 1128: 1125: 1101: 1100: 1051: 1049: 1042: 1036: 1033: 1008:inside walls. 996: 995: 946: 944: 937: 931: 928: 880: 877: 836: 833: 818: 817: 782:of the subject 780:worldwide view 775: 773: 766: 760: 757: 753: 752: 749: 738: 735:Collette Hoard 731:Stirling Hoard 715:Ringlemere Cup 698: 694: 676: 651: 650: 565: 563: 556: 521: 518: 512: 509: 498: 495: 482: 479: 466: 463: 453: 450: 417: 414: 405: 402: 374:archaeologists 369: 366: 362:mineralization 344:mineralization 338: 335: 330:mineralization 324: 321: 313:mineralization 308:phase response 298: 297:Discriminators 295: 270: 267: 257: 254: 183: 180: 175:Camille Gutton 161:James Garfield 125: 122: 75:magnetic field 32:metal detector 15: 9: 6: 4: 3: 2: 2374: 2373: 2362: 2359: 2357: 2354: 2352: 2349: 2347: 2344: 2343: 2341: 2330: 2328: 2327:0-7106-2555-3 2324: 2320: 2317: 2316:0-8109-4005-1 2313: 2309: 2305: 2304: 2283: 2279: 2273: 2266: 2262: 2257: 2250: 2246: 2241: 2234: 2229: 2221: 2215: 2207: 2201: 2193: 2189: 2182: 2166: 2162: 2158: 2152: 2137: 2131: 2121: 2113: 2109: 2103: 2096: 2092: 2087: 2079: 2073: 2065: 2061: 2055: 2047: 2040: 2032: 2025: 2017: 2013: 2007: 1999: 1993: 1985: 1981: 1975: 1967: 1963: 1957: 1949: 1945: 1939: 1931: 1927: 1921: 1913: 1907: 1899: 1886: 1878: 1874: 1867: 1859: 1850: 1842: 1841:www.louvre.fr 1838: 1832: 1816: 1810: 1794: 1788: 1772: 1766: 1759: 1747: 1743: 1736: 1734: 1725: 1721: 1717: 1713: 1709: 1705: 1701: 1697: 1690: 1682: 1676: 1668: 1662: 1658: 1651: 1643: 1637: 1629: 1622: 1614: 1607: 1600: 1596: 1591: 1584: 1580: 1575: 1568: 1562: 1555: 1551: 1546: 1539: 1534: 1526: 1520: 1513: 1509: 1504: 1496: 1490: 1483: 1479: 1474: 1467: 1463: 1458: 1451: 1447: 1442: 1438: 1428: 1425: 1423: 1420: 1418: 1415: 1413: 1410: 1407: 1403: 1402: 1398: 1396: 1393: 1391: 1388: 1387: 1381: 1379: 1375: 1370: 1368: 1364: 1360: 1356: 1350: 1348: 1344: 1340: 1335: 1331: 1321: 1318: 1316: 1312: 1309:prospecting, 1308: 1304: 1300: 1296: 1292: 1288: 1284: 1274: 1271: 1266: 1257: 1253: 1250: 1245: 1243: 1239: 1235: 1231: 1227: 1222: 1220: 1206: 1204: 1199: 1194: 1185: 1183: 1177: 1175: 1171: 1167: 1156: 1152: 1148: 1145: 1144:cluster bombs 1141: 1138: 1137: 1136: 1135:, including: 1134: 1133:military uses 1124: 1123: 1119: 1115: 1111: 1110:Lee de Forest 1106: 1097: 1094: 1086: 1076: 1072: 1068: 1062: 1061: 1057: 1052:This section 1050: 1046: 1041: 1040: 1032: 1030: 1029:United States 1025: 1023: 1018: 1014: 1009: 1007: 1003: 992: 989: 981: 971: 967: 963: 957: 956: 952: 947:This section 945: 941: 936: 935: 927: 925: 920: 916: 914: 910: 905: 903: 899: 894: 890: 888: 883: 876: 873: 868: 864: 860: 859:magnetometers 856: 851: 846: 841: 832: 830: 826: 814: 811: 803: 793: 789: 783: 781: 774: 765: 764: 756: 750: 747: 746:beach erosion 742: 741:Beach combing 739: 736: 732: 728: 724: 720: 716: 712: 708: 704: 699: 695: 692: 688: 684: 680: 677: 674: 673: 672: 666: 665:Mojave Nugget 662: 657: 647: 644: 636: 633:November 2013 625: 622: 618: 615: 611: 608: 604: 601: 597: 594: â€“  593: 589: 588:Find sources: 582: 578: 572: 571: 566:This section 564: 560: 555: 554: 549: 548: 539: 517: 511:United States 508: 506: 505: 504:bona vacantia 494: 492: 488: 478: 476: 472: 462: 458: 449: 447: 442: 437: 435: 431: 427: 423: 413: 411: 401: 399: 395: 391: 387: 383: 379: 375: 365: 363: 359: 354: 352: 349: 345: 334: 331: 320: 316: 314: 309: 304: 294: 292: 288: 284: 281:networks and 280: 275: 266: 264: 253: 250: 248: 244: 240: 236: 232: 227: 225: 221: 217: 213: 209: 206: 202: 198: 194: 189: 179: 176: 171: 168: 164: 162: 158: 155:In July 1881 153: 150: 145: 142: 135: 130: 121: 119: 115: 111: 107: 103: 99: 95: 90: 88: 84: 80: 79:eddy currents 76: 72: 69:producing an 68: 63: 61: 60:metal weapons 57: 53: 49: 45: 41: 37: 33: 25: 21: 2307: 2285:. Retrieved 2281: 2272: 2264: 2256: 2248: 2240: 2232: 2228: 2214: 2200: 2191: 2181: 2169:. Retrieved 2160: 2151: 2139:. Retrieved 2130: 2120: 2111: 2102: 2094: 2086: 2072: 2064:detecting.us 2063: 2054: 2039: 2024: 2015: 2006: 1992: 1983: 1974: 1965: 1956: 1947: 1938: 1929: 1920: 1906: 1885:cite journal 1866: 1840: 1831: 1819:. Retrieved 1809: 1797:. Retrieved 1787: 1775:. Retrieved 1765: 1757: 1750:. Retrieved 1745: 1702:(4): 76–85. 1699: 1695: 1689: 1675: 1656: 1650: 1627: 1621: 1612: 1606: 1598: 1590: 1582: 1574: 1566: 1561: 1553: 1545: 1533: 1519: 1511: 1503: 1489: 1481: 1473: 1465: 1457: 1449: 1441: 1401:Detectorists 1399: 1371: 1351: 1327: 1319: 1280: 1268:Garrett, an 1267: 1263: 1254: 1246: 1223: 1217: 1195: 1191: 1178: 1164: 1130: 1114:vacuum tubes 1107: 1104: 1089: 1080: 1065:Please help 1053: 1026: 1010: 1002:cover meters 999: 984: 975: 960:Please help 948: 921: 917: 906: 895: 891: 884: 882: 853:A series of 852: 849: 827:in 1987 and 821: 806: 797: 777: 754: 670: 639: 630: 620: 613: 606: 599: 587: 575:Please help 570:verification 567: 547:Detectorists 546: 514: 502: 500: 484: 468: 459: 455: 438: 419: 407: 371: 355: 340: 326: 317: 300: 276: 272: 259: 251: 228: 220:World War II 185: 172: 169: 165: 154: 146: 138: 91: 87:magnetometer 64: 31: 29: 2171:27 February 2161:Goring Kerr 2080:. NBC News. 1948:Communities 1930:Communities 1821:18 February 1799:18 February 1777:18 February 1554:Engineering 1347:frequencies 1330:transistors 1311:archaeology 1307:geophysical 1234:Los Angeles 1226:electronics 1174:blast waves 1083:August 2023 978:August 2023 913:transmitter 711:Newark Torc 707:Anglo-Saxon 679:Prospecting 661:gold nugget 404:Archaeology 358:mineralized 348:mineralized 269:Refinements 134:World War I 48:courthouses 2340:Categories 2300:References 2249:The Lancet 2141:22 October 2095:Radio News 1752:21 January 1283:industrial 1188:First idea 1170:mine plows 1155:explosives 825:Slack Farm 603:newspapers 520:As a hobby 351:black sand 291:smartphone 212:St Andrews 205:Lieutenant 116:to detect 94:land mines 67:oscillator 36:instrument 1877:1169-3835 1724:163861923 1636:cite book 1287:landmines 1054:does not 949:does not 902:Mars bars 867:Outokumpu 800:June 2013 792:talk page 398:artifacts 283:Bluetooth 201:Lake Nemi 24:U.S. Army 2165:Archived 1849:cite web 1716:25616646 1384:See also 1293:such as 1166:Demining 1035:Military 924:conveyor 786:You may 725:, Roman 497:Scotland 245:and the 52:airports 2351:Hobbies 2125:pp21-25 1374:tinfoil 1291:weapons 1228:at the 1151:weapons 1075:removed 1060:sources 970:removed 955:sources 617:scholar 485:In the 394:bullets 382:jewelry 44:prisons 2325:  2314:  2287:10 May 1875:  1795:. HMSO 1773:. HMSO 1722:  1714:  1663:  1395:DEMIRA 1359:copper 1355:silver 1313:, and 1295:knives 1022:analog 1017:copper 713:, the 697:water. 691:copper 689:, and 687:silver 619:  612:  605:  598:  590:  540:, 2016 452:France 241:, the 98:knives 34:is an 1837:"404" 1720:S2CID 1712:JSTOR 1433:Notes 1182:bombs 624:JSTOR 610:books 538:Japan 386:coins 279:Wi-Fi 40:metal 2323:ISBN 2312:ISBN 2289:2021 2173:2024 2143:2023 1898:help 1873:ISSN 1858:help 1823:2018 1801:2018 1779:2018 1754:2017 1661:ISBN 1642:link 1378:gold 1376:and 1363:iron 1357:and 1299:guns 1297:and 1172:and 1153:and 1058:any 1056:cite 1013:coil 953:any 951:cite 683:gold 596:news 439:The 428:, a 376:and 368:Uses 216:Fife 102:guns 100:and 54:and 1704:doi 1406:BBC 1305:), 1069:by 964:by 705:of 579:by 469:In 420:In 287:GPS 2342:: 2280:. 2263:, 2247:, 2190:. 2159:. 2110:. 2062:. 2014:. 1982:. 1964:. 1946:. 1928:. 1889:: 1887:}} 1883:{{ 1853:: 1851:}} 1847:{{ 1839:. 1756:. 1744:. 1732:^ 1718:. 1710:. 1700:32 1698:. 1638:}} 1634:{{ 1597:, 1552:, 1176:. 904:. 733:, 729:, 721:, 717:, 685:, 436:. 388:, 384:, 303:RF 249:. 214:, 50:, 46:, 30:A 2318:. 2291:. 2194:. 2175:. 2145:. 2114:. 2066:. 2048:. 2033:. 2018:. 2000:. 1986:. 1900:) 1896:( 1879:. 1860:) 1843:. 1825:. 1803:. 1781:. 1726:. 1706:: 1669:. 1644:) 1615:. 1527:. 1497:. 1404:( 1096:) 1090:( 1085:) 1081:( 1077:. 1063:. 991:) 985:( 980:) 976:( 972:. 958:. 813:) 807:( 802:) 798:( 784:. 748:. 646:) 640:( 635:) 631:( 621:· 614:· 607:· 600:· 573:. 550:. 261:(

Index


U.S. Army
instrument
metal
prisons
courthouses
airports
psychiatric hospitals
metal weapons
oscillator
alternating current
magnetic field
eddy currents
inductive sensor
magnetometer
land mines
knives
guns
airport security
treasure hunting
construction industry
steel reinforcing bars

World War I
Heinrich Wilhelm Dove
David Edward Hughes
Alexander Graham Bell
James Garfield
Camille Gutton
Gerhard Fischer

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