Demystifying Metal Detector and Revolutionary Technologies Behind IT
The metal detector is a simple but very effective device that is used to find metal components in water and on the ground. Initially, it was only meant for screening and security purposes as well as to locate mines. Today, however, this has really changed. There are numerous industries that rely on the metal detector for their daily operations including food processing, pharmaceuticals, textiles, chemicals and plastic industries.
These industries have to ensure that metal is not present in their products since it might lead to contamination and negative effects such as food poisoning as in the case of food processing industries. There is also a significant number of persons who use the metal detector for treasure hunting and finding old coins. The metal detectors that are used in most cases are electronic and can easily be carried around. The handheld devices come in handy especially when you want to cover more ground in a short duration. To better understand the metal detector, let's start with how it works.
Demystifying Metal Detector and Revolutionary Technologies Behind IT
How does the metal detector work?
The working principle behind the metal detector is a simple one. When the electricity goes through a conducting loop, it produces a magnetic field around it. To get the current flowing in the detector, there is an alternator as one of the inbuilt components. This component produces the alternating current. As the current flows in the loop, a magnetic field is produced close to it.
The changing magnetic field will produce current if brought close to a conductor through induction. The induced current will, in turn, produce a magnetic field that will interfere with the original one. The metal detector is fitted with a receiver coil that detects any changes in the magnetic field. The changes will be caused by materials that conduct electricity only, these are metals.
The interference will be signaled as beeps to the operator once metal is detected. There are several technologies that are used in metal detectors including very low frequency (VLF), pulse induction and beat frequency oscillator (BFO) technologies. To understand the metal detector further let's look at the technologies individually.
Very Low Frequency (VLF) Technology
The VLF technology is the most common one in metal detectors today. In the setup, there are coils in sets of two making up the receiver and transmitter coils. The transmitter coil is the one with electric current flowing and produces a magnetic field that moves around the area of interest. The magnetic current that is generated will react when in close proximity of a metal because it is an electric conductor.
The metal will create a disturbance in the magnetic field created by the transmitter coil. The design of the receiver coil ensures that it is not affected by the magnetic field generated by the transmitter coil and will only react to what comes from metallic objects. The electric current produced weakens when the device is close to a conductor.
This current will, in turn, be amplified and the electric frequency sent to the control box for analysis. This is the reason the metal detector is said to work using the VLF technology. It is preferred because it can determine the disparity between different types of metals as well as the depth of the metal object.
Pulse Induction Technology
The Pulse Induction Technology, simply known as PI, is a little bit different since it uses only a single coil for both the transmitter and the receiver. This is its basic setup, however, in other versions, it is possible to employ two or three coils. The metal detector works by sending short bursts or pulses of electric current in the coil. This leads to the generation of shorter magnetic fields.
In every pulse, the magnetic field that is created will eventually reverse in polarity and collapse. An electrical spike can also be created but also lasts for a short duration. When the magnetic field and spike collapse, an electric current that is known as reflected pulse will be created in the coil and only lasts for a few seconds. Now here is where the magic happens. The reflected pulse will last much longer in the presence of a conductor.
The reason behind this is that the opposing magnetic field that is created by the metal will lengthen its duration. The presence of an integrator in the metal detector allows for closer monitoring of every spike. This converts the signals that it gets and amplifies them before conversion to direct current. The produced current, connected to an audio circuit will allow for detection of metal objects that come in contact with the detector.
Beat Frequency Oscillator (BFO) Technology
The BFO technology is similar to the VLF technology in that it also uses two wire coils in its basic setup. In this case, the first coil is found in the control box where signals are transmitted and processed. The second coil is strategically placed in the search head. The two coils are connected to the oscillator that actively sends thousands of electric pulses every second.
When the pulses go through the coils, radio waves are created and the receiver that is in the control box collects all these signals. When you have the audio, circuit connected, you will hear clear tones similar to radio wave frequency due to the receiver. The electric current in the search head will have created a magnetic field that will experience interference in the proximity of metal objects.
The creation of radio waves in the search head together with the interference can, therefore, be identified easily in the audio circuit. This is how the technology allows the metal detector to identify metals that are close to the search head. This technology has been employed in some of the metal detectors that we use because it allows the operator to distinguish between different objects and specifies their location.
Conclusion
These are the common technologies that you will find behind most metal detectors- The functioning of the metal detector is pretty much the same regardless of the technology it uses. Using this information, you can make an informed decision when purchasing your next metal detector.
