Metal Detector Buying Advice
Under different situations, to mention the words metal detector, you will get completely different reactions from different people. For example, some people think of combing a cave in search of coins or buried treasure. Other people think of airport security, or the handheld scanners at a concert or sporting event. The truth is that all of these scenarios could be real. Metal-detector technology is a huge part of our lives, with a range of uses that spans from leisure to work to safety.
The metal detectors in airports, office buildings, schools, government agencies and prisons help ensure that no one is bringing a weapon onto the premises. Consumer-oriented metal detectors provide millions of people around the world with an opportunity to discover hidden treasures around them.
The actual usage of metal detectors is based upon the rules of electromagnetic induction. Metal detectors contain one or more inductor coils that are used to interact with metallic elements on the ground. The single-coil detector illustrated below is a simplified version of one used in a real metal detector. A pulsing current is applied to the coil, which then induces a magnetic field. When the magnetic field of the coil moves across metal, such as the coin in this illustration, the field induces electric
currents in the coin. The eddy currents induce their own magnetic field, which generates an opposite current in the coil, which induces a signal indicating the presence of metal.
Most of the metal detectors use two oscillators; each of them produces a radio frequency. One of these oscillators uses a coil of wire that is called as the search loop. The second oscillator uses a much smaller coil of wire, and is usually inside the control box and is usually called the reference oscillator. By adjusting the oscillators so their frequencies are almost the same, the difference between them is made audible as a beat note, this beat note changes slightly when the search loop is moved over or
near to a piece of metal. It has been found in practice best to make the search oscillator fixed say at 100 kHz and to arrange for the reference oscillator to be adjustable 100 kHz plus or minus 250 Hz. This gives a beat note of 250 Hz to 0 to 250 Hz. The beat note disappears or nulls when the two oscillators are about equal. This type of detector is most sensitive when the beat note is close to zero, about 5 Hz (motor boating) any slight change being noticeable.
Maybe you're close to the ocean or lakes, and are thinking of jumping in the water with your metal detector to find out what was lost there? If finding jewelry is your thing then a waterproof detector is a must. Waterproof detectors could be still functional even in deep water.
Buying Tips:
When buying a metal detector for home security, make sure that you determine where to put the metal detector. You don't want the metal detector to go off everytime someone walks in the door with a belt buckle. For the most part, you want to have your metal detector protecting a room with your highly valued prized belongings. Most metal detectors you buy are the ones to help you find items containing metal on the ground. Those probably would not be useful for home security. You want to the ones that can fit around
a doorway. It is best to ask a professional home security company to determine if you even need metal detectors for your home.
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