The history of the metaldetector
Metal detectors have been around for much longer than most people realize. Towards the end of the 19th century, many scientists and engineers used their growing knowledge of electrical theory in an attempt to devise a machine which would pinpoint metal. The use of such a device to find ore-bearing rocks would give a huge advantage to any miner who employed it. The German physicist Heinrich Wilhelm Dove invented the induction balance system, which was incorporated into metal detectors a hundred years later. Early machines were crude and used a lot of battery power, and only worked to a very limited degree. The Scottish physicist, Alexander Graham Bell, used such a device to attempt to locate a bullet lodged in the back of American President James Garfield in 1881.
The modern development of the metal detector began in the 1930's. Gerhard Fisher had developed a system of radio direction-finding, which was to be used for accurate navigation. The system worked extremely well, but Dr Fisher noticed that 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 should be possible to design a machine which would detect metal "metal detector", using a search coil resonating at a radio frequency. In 1937, he applied for, and was granted, the first patent for a metal detector. His designs were soon put to the test in a practical way, as they were used as mine detectors during the Second World War. They were heavy, ran on vacuum tubes, and needed separate battery packs - but they worked. After the war, there were plenty of surplus mine detectors on the market; they were bought up by relic hunters who used them for fun and for profit. The hobby of metal detecting had been born.
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How does a metaldetector work?
Is it necessary to know how a metal detector works in order to use it effectively? Absolutely not. Will knowing how it works help someone to use it more effectively in the future? Quite possibly yes, but only with persistence and practice. The best metal detector available is still only as good as the person using it.
Metal detectors work on the principal of electromagnetism and their effects on conductive metals. The high-powered coil of metal, called the transmitter, uses the battery power to generate a penetrating magnetic field. As the electromagnetic field enters the ground, anything metallic will become charged with magnetism. When the receiver in the coil detects the electromagnetic signature, it sends a signal to the electronic box. A speaker amplifies this signal and the operator hears a beep. Microprocessors located in the electronic box can actually measure the time between the charging and the receiving (called a phase shift) and determine which metals may be present. This is how high-end metal detectors can be adjusted to only search for certain metals.
There are several technologies the detector can work after.I will not go further in on each technology here. But we have what we call Non-Motion and motion detectors,depending on if the coil has to be in motion or not in order to detect an object. And there are technologies such as:PI ,Vflex, VLF,BFO and so on. Below you can find some of the different brands of detectors which are on the market right now:
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