Metal detectors are helpful in uncovering all sorts of metal items, including coins, jewelry, and even gold. It’s quite fascinating to learn how the devices work. Lenz’s law of electromagnetism states that at the time a conductor drops within a particular range of an alternating magnetic field, it makes its own oscillating field. That goes against the primary field.
A magnetometer is able to detect the changes within the overall field. It signals when a conductive object is close. It’s usually a bit of metal. Metal detectors’ ranges vary from a couple feet for the tiniest coils, up to 10 feet (3 meters) for 12-15-inch coils.
The key part of a working metal detector is the eddy currents created by conductive objects inside the environment. It’s like pushing a canoe paddle through a body of water. It can cause small vortices to show up on the surface of a lake, for example when the electrons contained in metal create an oscillating field.
The best results are produced with frequencies ranging from 3 to 20 kHZ. Meanwhile, some of today’s best metal detectors allow users to adjust the alternating field’s frequency.
Meanwhile, a newer type of metal detector utilizes a kind of tech known as pulse induction. This type of metal detector hits the ground with huge electromagnetic pulses, and detects the amount of time needed for voltage to drop to ambient levels. When there’s a conductive object underneath the ground, it will take longer for the voltage to drop. Its’ a tiny effect, but today’s sensor can detect it well. This particular method has particular advantages over standard metal detectors. They include the capability to pick up objects below the “black sand,” which is highly mineralized.
Metal detectors have many applications. The most critical one is the ability te locate mines or explosive devices that are buried right below the ground’s surface. On nations where mines still exist from past wars, people are asked to use metal detectors when they talk through unknown areas that were at risk for land mines. The gadgets are able to save many people lives.
Metal detectors can also be used for finding various types of so-called “buried treasure.” That includes coins/relics that were buried years or even thousands of years ago. Metal detectors can even pick up objects that were lost a couple days in the past. It’s an excellent task for a hobbyist.
Very low frequency (VLF) metal detectors work on the scientific principle known as conductivity. They locate any metal that has a conductive surface with a distance of 18” to 2 feet from the ground’s surface. A signal can be heard since an electromagnetic field is created and then flows out into the area away from the device’s search coil. As the electromagnetic field enter the metals’ surface, small electrical currents known as eddy currents flow into the metal’s surface. The eddy current then creates electromagnetic fields that radiate in all directions within space. The currents that radiates up towards the search coil winding are detected. A lower voltage then is fed into amplifying wires.