How Metal Detectors Work
How metal detectors work? This is the questions that many people
interested in gold detector devices ask, and here in this article we will
explain this in details
Introduction
Metal
detector device is an electronic device that used to find buried metallic
objects underground; it can be used for multiple purposes like searching for
ancient coins or buried treasure or relics and even gold.
For
best metal detectors and gold detectors devices you can visit this site:
Metal
Detector Parts
A typical metal detector is light-weight and consists of just a
few parts:
1. Stabilizer which used to keep the unit steady as you sweep the
coil back and forth
2. Control box usually contains the electronic circuits ,
display screen , ,control panel consists of many buttons or controls , speaker, batteries and
the microprocessor
3. Shaft used to connects the control box and the coil; its
length is often adjustable so you can set it at a comfortable level for your
height
4. Search coil this is the part of metal detector that
actually senses the metal; also known as the "search head,"
"loop" or "antenna"
Some metal detectors devices also have a jack for
connecting headphones, and some have the control box below the shaft and a
small display unit above.
But How metal detectors work?
Metal
Detector Search Technologies
1 - VLF Technology
Very low frequency (VLF), also known as induction
balance, is probably the most popular detector technology in use today. In a
VLF metal detector, there are two distinct coils:
·
Transmitter coil -
This is the outer coil loop. Within it is a coil of wire. Electricity is sent
along this wire, first in one direction and then in the other, thousands of
times each second. The number of times that the current's direction switches
each second establishes the frequency of the unit.
·
Receiver coil this
inner coil loop contains another coil of wire. This wire acts as an antenna to
pick up and amplify frequencies coming from target objects in the ground.
How does a VLF metal detector distinguish between different metals?
It relies on a phenomenon known as phase shifting. Phase shift is the
difference in timing between the transmitter coil's frequency and the frequency
of the target object.
Basically, this means that an object with high inductance is
going to have a larger phase shift, because it takes longer to alter its
magnetic field. An object with high resistance is going to have a smaller phase
shift
There are many devices that work using this technology like Gold
Monster 1000, Impact, and Gold Racer …etc.
Visit this links for more info about these devices:
2- Pulse Induction
Technology
A less common form of metal detector is based on pulse induction
(PI) technology. Unlike VLF, PI systems may use a single coil as both
transmitter and receiver, or they may have two or even three coils working
together. This technology sends powerful, short bursts (pulses) of current
through a coil of wire. Each pulse generates a brief magnetic field. When the
pulse ends, the magnetic field reverses polarity and collapses very suddenly,
resulting in a sharp electrical spike. This spike lasts a few microseconds
(millionths of a second) and causes another current to run through the coil.
This current is called the reflected pulse and is
extremely short, lasting only about 30 microseconds. Another pulse is then sent
and the process repeats. A typical PI-based metal detector sends about 100
pulses per second, but the number can vary greatly based on the manufacturer
and model, ranging from a couple of dozen pulses per second to over a thousand.
If the metal detector is over a metal object, the pulse creates
an opposite magnetic field in the object. When the pulse's magnetic field
collapses, causing the reflected pulse, the magnetic field of the object makes
it take longer for the reflected pulse to completely disappear.
There are many devices that work using Pulse Induction
technology like Lorenz Z1, Garrett ATX…etc.
For details visit these links:
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