How Does a Metal Detector Work?

metal detector fits kids and adults

Metal detectors are characterized by their wide detection range, accurate positioning, high resolution, and ease of operation. The metal detector is mainly used to detect and identify metal objects buried underground.

Where can you use a metal detector?

In addition to military applications, it is also widely used for: security checks, archaeology, prospecting, finding scrap metal; a good helper for recycling scrap metal objects.

The structure of a metal detector

A typical metal detector is light in weight and consists of only the following components:

  • Stabilizer: keeps the device stable while scanning back and forth with the detector (optional)
  • Control console: contains the circuitry, control mechanism, speaker, battery, and microprocessor
  • Connection bar: connects the console to the search coil; it is usually adjustable so that you can adjust its height according to your height
  • Search coil: the component that senses metal; also known as a “search probe”, “coil” or “antenna”
the structure of metal detector
The structure of the metal detector

Most metal detectors also have a socket for the handset, some have the console below and the lever and a small display above.

The average metal detector is very easy to operate. Once the detector is switched on, simply allow the detector to move slowly over the area you wish to search. If the target is swept, the detector emits a signal that you can hear.

More advanced metal detectors are equipped with a display that accurately identifies the type of metal found and how deep the target is buried in the ground.

How does a metal detector work?

Metal detectors use the principle of electromagnetic induction to produce a rapidly changing magnetic field using a coil with an alternating current passing through it. This magnetic field generates an eddy current inside the metal object. The eddy currents, in turn, generate a magnetic field, which in turn affects the original magnetic field and triggers the detector to chirp.

search coil
How does a metal detector work

Metals are buried underground and are detected through thick layers of earth, which are inevitably affected by the geological structure. The earth contains a variety of minerals which can also cause the detector to generate a signal which can mask the signal of the metal and cause false alarms.

Anyone who has ever used a metal detector will have experienced this, as the proximity of mounds of earth, stones, and bricks will emit an alarm tone, a phenomenon known as “mineralization”. For this reason, domestic metal detectors can only detect shallow surface metal objects, bounty hunters metal detectors are equipped with an advanced ground balance system, which can exclude all mineralization reactions, greatly improving the detection depth and effect of the instrument.

The detection depth of all detecting instruments has a great relationship with the area, shape, weight, burial time, soil quality, soil moisture, the user’s proficiency, generally speaking, the larger the area, the greater the quantity, the less soil moisture, the lower the density, the longer the burial time, the more conducive to increasing the detection depth of the detector.

The depths indicated for the instrument are the maximum depths that can be achieved under optimum conditions according to the industry standard for the product. In addition, the depth of detection can be attenuated by low-power levels and insufficient transmitting power, in which case the batteries need to be replaced promptly.

Uses of metal detectors

Metal detectors are in our lives, from recreation to work to safety and security, they have a wide range of uses. Metal

  • Metal detectors are used in airports, office buildings, schools, government institutions, and prisons to help ensure that no one enters these premises with dangerous weapons.
  • Coin shooting is specifically targeting coins.
  • Search for lost coins or jewelry on the beach.
  • Metal detectors can also be used to detect wires hidden in walls, buried water pipes, and cables, etc.
  • Rugged metal detector ideal for detecting treasure in extreme ground conditions.
  • Detects a wide range of metals, from iron, coins and household items to precious metals such as silver and gold.
uses of the metal detector
Uses of the metal detector

The main factors affecting detector accuracy

How deep can a metal detector detect? Most detectors have a normal maximum detection depth of around 20 to 30 cm. The exact value of the detection depth is influenced by several factors.

  • Type of metal detector
  • The type of metal in the target
  • The size of the target
  • The composition of the soil
  • The side band effect of the target
  • Interference from other objects: e.g., pipes or cables, but also objects above ground, e.g., power transmission lines.

Classification of metal detectors: by function

  1. All-metal detectors: all metals such as iron, stainless steel, copper, and aluminum can be detected. Detection accuracy and sensitivity are relatively high, stable, and reliable.
  2. Iron metal detector: can only detect ferrous metals, commonly known as needle detectors. Detection accuracy and sensitivity are low, easy to interfere with. Usually called “needle detector”, “needle inspection machine”, “over-needle machine”.
  3. Aluminum foil metal detectors: also only detect ferrous metals, but still have high accuracy and sensitivity when detecting products packaged in aluminum foil.

How much is a metal detector?

Metal detectors look similar in appearance, but the technology used in each product is different. Detectors are just like any other commodity, the performance of the product is proportional to the price. The price of a detector varies with its performance, brand, and technology used.

There are treasure detectors as well as gold detectors. Treasure detectors have a metal identification function that tells the type of metal and obviously, the more accurate the metal identification function the finer the range, the more expensive it is.

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