Sunday, October 30, 2011

Metal Detectors: How do they work?

Metal detectors are handheld devices that are designed to use electromagnetism to detect metal where it may not be seen. They are used for many military and industrial purposes, but we are most interested in their personal use capabilities most notably for treasure hunting.

The origins of the modern metal detector trace back to the 19th century and the invention of the induction balance system by Heinrich Dove. These prototypes were much cruder, less effective, and typified by their enormous use of battery power. The modern metal detector was invented by Gerhard Fisher in the 1930s, who received the first patent for such a device.

When powered on, the metal detector is swept across the ground. All metal detectors work on either electrical or magnetic impulses. There are three main types of metal detector technology: very low frequency, pulse induction, and beat-frequency oscillation. Metal detectors have coils, located in the big round part at the end of the metal detector. Electricity or an electromagnetic charge is sent through the coils to the ground and back to the coils. Metallic objects interrupt the signal, which results in the unit creating an audible sound. The sound, usually a beep of some sort alerts the treasure hunter that there is a metal object present.

Modern metal detectors feature an array of systems that refine the detection capabilities of the device. They help the metal detector and the user change the sensitivity of the detector, as well as the depth and the range of the device. Metal detectors have consistently gotten lighter and more sensitive over the decades and the potential for the detectors of the future looks great.

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