The History of Metal Detectors

                                    The History of Metal Detectors

　
Lets take a trip back in time. Back to 1881. For that was when the first metal detector was made. In 1881, Alexander Graham Bell invented the first metal detector. As President James Garfield lay dying of an assassin's bullet, Alexander Graham Bell hurriedly invented a crude metal detector in an unsuccessful attempt to locate the fatal slug. The metal detector worked correctly but the attempt was unsuccessful because the metal coil spring bed　Garfield was lying on had confused the detector.

　The first modern metal detector was made when Gerhard Fisher had developed a system of radio direction-finding, which was to be used for accurate navigation. In 1925, he applied for, and was granted, the first patent for a metal detector.

　Many manufacturers of these new devices brought their own ideas to the market. In the 1950s White's Electronics of Oregon began by building a machine called the Oremaster Geiger Counter. Another leader in detector technology was Charles Garrett, who pioneered the Beat Frequency Oscillator machine. In the 1950s and 1960s, the invention and development of the transistor  allowed metal detector manufacturers and designers to create smaller, lighter machines with improved circuitry.

  The biggest technical change in detectors was the development of the induction-balance system. This system involved two coils that were electrically balanced. When metal was introduced to their vicinity, they would become unbalanced. This allowed the detectors to discriminate between metals, because every metal has a different phase response when exposed to an alternating current. A disadvantage of discriminators was that they reduced the sensitivity of the machines.

　With new coil designs and pulse induction, metal detectors have come a long way from their predecessors. There are many different types and uses of metal detectors, more than you might realize. There are ones made for hobbyists(like you), for the military, and there are ones used by archaeologists. Also, let’s not forget the kinds used for security screening　at your local airport. Metal detectors are also used in the industrial world to find contamination in food from metal shards broken from the processing machinery during the manufacturing.

Leave a comment below and tell us what your favorite detector is. With so many types and brands of metal detectors to choose from, what do you think is the best one you've used?

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