Understanding How Metal Detectors Work and How to Choose
A metal detector is an equipment that is used in the detection of the presence of metals in concealed inclusions. Metal detectors were invented back in the 1800s just after electricity was invented. They were majorly used in industries and at the mines. In mining, they were used in finding landmines and mineral prospects.
Today, the metal detector has undergone a lot of improvements and can be used in multiple sectors. Apart from mining and industrial use, metal detectors have gained a pivotal use in security. They are used to detect metallic weapons such as guns in access points. These are common in prisons, airports, hotels and other public places such as offices and government offices. Metal detectors are also used to detect foreign bodies in food.
Types of metal detectors and how they work
There are three types of detectors:
1. Beat frequency Oscillation (BFO)
This is the simplest metal detection system there currently is. They are mostly used to detect metals in the ground. This type of detectors works through 2 coils of wire. One is located at the in the head of the detector while the other one is in the control box of the detector. These two wire coils are connected to an oscillator.
This oscillator has the ability to generate thousands of pulses of electric current per second. The coils produce radio waves every time a pulse passes through them. The radio waves are then received by a receiver which is in the control box. The receiver produces an audible sound to alert the user of metal presence depending on the difference of the frequency. This type of detectors is the simplest and they can be cheaply purchased by many consumers. However, they may not give very accurate results.
2. Very low frequency (VLF) metal detectors
This type of detectors is the most popular today. The technology is also used across many detector models in the market today. Compared to BFO metal detectors, they are costlier but the results are more accurate as well. The VLF detector basically has three parts which include the transmitter, two coils, and the receiver. The outer coil Loop generates current in two directions. This is also known as the transmitter coil.
The transmitter coil establishes the frequency of the metal detector. The establishment is dependent on the number of times that the current shifts direction. The inner coil loop is also known as the receiver coil. Its main function is target detection and amplification of frequencies from the ground. The transmitter coil can loop the strongest electric current either above or below the ground. an audible sound is produced when the current from the receiver coil contacts a target.
3. Pulse Induction Detectors
This type of detectors is particularly used in gold detection and are used for targets that are deep in the ground. PI detectors are expensive and are used in places with a high mineral content. This technology has a 1 coil that acts as both receiver and transmitter. The coil transmits electric pulses into the ground thus creating a magnetic field.
Once the pulses come into contact with a target in the ground, a signal is sent by reversing the magnetic field What to consider when selecting a metal detector. For a new user or customer, it may not be easy to know what exactly to look for when selecting a metal detector. I have a compiled a list of important features to look for in your selection.
They include: Discrimination
This is the capacity of a detector to differentiate between metals. Each particular metal produces a different sound on identification. Detectors with this ability can identify them. This is very important for people in the mining and security fields. Discrimination levels differ with the many models of detectors.
However, the higher the discrimination level, the higher the price of the detector. Size and shape of the coil. Depending on where the metal detector is supposed to be used, the shape and size of the coil is very important. The shape and size of a coil determine how far and deep the magnetic field of a detector can reach.
There are various types of coils
They penetrate up to 12 inches. Their oval shape enables them to cover a bigger distance. Concentric coils. They cover up to 12 inches and have the standard shape.
Double D coils
They don't have a depth capacity but they have the biggest ground range. Concentric coils. They are the best to use in areas with thick undergrowth’s and can penetrate up to 12 inches.
This is the ability to determine the density and size of the metal. This is really helpful for treasure hunters. This feature is found in enhanced metal detectors.
Sensitivity is a feature that varies on the use of the detector. Detectors used to find metals in the topsoil or very small pieces of metals need to have high frequencies and vice versa. One should always adjust the sensitivity settings on the detector every time they are using it on a new ground. reading the user manual can also help in understanding the sensitivity settings better.
This is also known as calibration and it accounts for all metallic minerals found in a soil. Detectors with a high calibration are less prone to external interference from foreign signals. Calibration settings can be adjusted in the control box of the metal detector.
Different customers have different needs. One can always choose the type of detector that meets all their needs.
This is the ability of a detector to produce different tones according to different sizes and types of the metals detected. for instance, gold producing a higher tone than other metals.
Power level indicator
Portable metal detectors use batteries for operation. This means that users have to keep checking the power levels every now and then. A metal detector with a power level indicator will be easier to manage especially for people who use their detectors regularly. This is applicable to metal detectors used for security scans and mineral hunting.