History of the hobby metal Detector.

I thought I’d do a proper write up on the history of the hobby metal detector as very few quality articles seem to exist on the subject and are presented in a format that is difficult to digest. Enjoy!

The very beginning – Alexander Graham Bell.

Alexander Graham Bell invented the world’s first metal detector in 1881. Why did he do this? To retrieve a bullet from then president James Garfield who lay dying from the fatal assassins bullet wound. He speedily put together a very crude metal detector in a failed attempt to detect the bullet in the presidents body (the detector worked! But the bed was made of metal confusing the machine!). His metal detector was an electromagnetic tool he called the “induction balance”.

The early years – Gerhard Fischar.

You may know the name Garhard Fischar (Fisher metal detectors) as he received the worlds first metal detector patent and is considered to have made the world’s first modern portable metal detector in 1925. His machine was first sold commercially in 1931shortly before world war 2. He is also responsible for the first mass production of the metal detector.

Gerhard stumbled onto the solution after seeing errors and problems in another project he was working on for airborne direction finding equipment. The solutions he came up with for the problems helped him in creating the metal detector.

The world’s first to apply for such a patent was Shirl Herr in 1924 to help Benito Mussolini recover treasures of Emperor Caligula’s galleys from the bottom a lake Nemi in 1929 (another incredibly fascinating story). Admiral Richard Byrd’s Second Antarctic Expedition in 1933 also used Herr’s machine to find artifacts left by early explorers to the region. His machine was effective to 8 feet down! Incredible!

War years – Polish mine detector

As with many technologies the metal detector also got its development boost for war time applications during World War 2. A Lieutenant Jozef Stanislaw Kosacki, a Polish military officer that was in the polish resistance based in Scotland during early World War 2 refined this design to make a Mine-Detector. Evidently this was a heavy beast with vacuum tubes and heavy battery packs. 500 of these were sent to El Alamein to clear German mine fields. It was even used after D-Day landings in France. The technology though became top secret due to the war and remained so for many years.

Technological refinement – Whites and Garrett.

In 1950 Whites electronics created the Oremaster Geiger Counter. Charles Garrett then pioneered the Beat Frequency Oscillator machine. The metal detector came of age with small batteries, better circuitry and light weight designs. Companies soon began to supply growing demand in the US and Britain in the 1960’s.

It was yet again another war which helped boost the popularity of detectors for personal use. After the Korean War many US veterans who used the machines for mine detecting carried on using them at home for hobby applications.

Early modern detectors – the age of discrimination.

Discriminators came about around the 1970’s with the use of induction balance system which uses 2 coils that are electrically balanced outside the presence of metal. Each metal type has a different effect “Phase response” on the alternating current. Thus we could now avoid Iron and other metals if we wanted to! Unfortunately as we know some metal give the same response – Gold and Foil are very close! Darn! Also in the 70’s the double D coil came about as well as the ability to switch between discriminate and non-discriminate modes. The induction and oscillator machines are low current and low frequency.

Pulse induction was also developed in this time (and probably perfected by Minelab). High voltage pulses are sent into the ground, where no metal the signal disappears at a uniform rate and returns to 0. If metal exists it interferes with the speed at which the electronic pulse “disappears” or reaches 0 again. Each metal has unique effects on this rate of decay and can be detected by the hobby metal detector. The big benefit is the fact that ground minerals is salt water areas and gold fields do not affect these machines!

Modern hobby metal detectors

Today the metal detector is a sophisticated advanced hobby device with many features incorporated. From discriminating between metals, eliminating certain metals, sensitivity adjust, LCD screens and volume adjustment to waterproof casings capable of detecting 200 feet down, and now even cloud computing, wireless headphones and built in GPS thanks to Minelab.

Hope you enjoyed this blast from the past!

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