The working mechanism of pulse induction metal detectors
Pulsed induction metal detectors are electronic devices belonging to metal detectors that work according to pulse induction technology, which in turn depends on the principle of electromagnetic induction.
Pulsed induction and its technology
The systems of Pulsed induction use a single coil that works on transmitting and receiving, and it can contain two or three coils working together.
In this process, pulses of electric current are sent through a coil of metal wire, and each pulse generates a magnetic field .
and when the pulse ends, it reverses the polarity of the field and suddenly fades away, generating a sharp electric shock that lasts for a few millionths of a second, and causes another current to pass through the coil and we call this current the reflected pulse . It lasts for a short period and again it send a new electrical pulse and the process is repeated.
A typical pulse induction metal detector sends about 100 electrical pulses per second . but the number can vary according to the manufacturer, model, quality, and type from a few pulses to thousands of pulses per second. When the device passes over a metal object, the pulse forms an opposite magnetic field in the body.
The working principle of pulse induction metal detectors
It generates an electric current through alkaline batteries . and they generate strong and short pulses of current that pass through a set of coils of copper wire, and each pulse generates a short magnetic field seconds and causes another current to pass through the coil .
We call this current the reflected pulse and it is very short and lasts only about 30 microseconds, then another pulse is sent and the process is repeated.
Where are the uses of pulse induction metal detectors ?
-Unearthing ancient coins, which is the process of searching for historical coins, which were made of gold, silver, or copper, and is a hobby spread all over the world.
–detecting for natural raw gold, that we find in some areas in the form of granules called gold nuggets or in the form of rock veins of gold or mixed metals of other minerals and impurities.
-looking for metals of all metals . these metals are divided into ferromagnetic metals such as iron and non-ferrous metals such as silver.
-Searching for discarded or lost items and man-made valuables . for example jewelry, cell phones, cameras, and other devices.
-Combing the beaches on the seas and oceans to search for lost coins or jewelry such as : lost rings, chains, collars, and other ornaments and metal tools
-There are types of these devices that are waterproof to allow searching for submerged objects in shallow water.
Metal detectors are an excellent solution for finding buried objects . but the object must be within a certain depth of the surface (usually not more than 30 cm), but the exact depth varies according to several factors:
- The type of metal detector device, where the technology in which the device operates plays a major factor in its capabilities .
and there are some features or differences that distinguish devices that work with the same technology, for example, some metal detectors that operate with VLF technology use higher frequencies than others .
While some provide different size search disks as well as the sensor Or the signal amplification technology can differ from one device to another according to the manufacturer or even within the different models of the same device
- The nature of the buried body, where some minerals such as iron, for example, make magnetic fields stronger than the rest of the minerals.
- The size of the piece where the discovery of very small pieces becomes more difficult at greater depths.
- Soil composition, where some soils contain metals to electrically conductive minerals and can seriously interfere with the field generated by the device.
- Interference from other objects in the ground such as pipes and wires. or objects above the ground such as electric current lines
In the end, we note that these devices have their own uses and various features . so everything that is sought to be searched or explored will have the appropriate device . and this type of device varies with the diversity of manufacturers in terms of quality and capabilities.
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