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how a metal detector works simple
Introduction: metal detectors are fascinating machines. Many of the people who use them are excited in the decant the virtues of their favorite tools as are in effect looking for hidden treasures. It is necessary to know how a metal detector works in order to use effectively? Absolutely not. Find out how you can help someone to use it more effectively in the future? It may be, but only with persistence and practice. The best metal detector available is still the one who uses it.
TR VLF (Very Low Frequency Transmitter & Receiver)
Transmitter within the metal detector coil (also called research head, antenna, etc.) there is a wrapping of thread called “transmitting coil”. The electric current is sent to the coil to create a magnetic field. The current flow direction reverses some thousands of times every second; the transmission frequency “operating frequency refers to the number of times per second that the current flow is clockwise direction to counterclockwise to go back to standard time. When the current flows in a given direction, it produces a magnetic field whose polarity (as the North and South poles of a magnet) lines on the ground; When the current is inverted, it reverses the polarity of the magnetic field that penetrates into the soil. Some metal objects (or other conductors of electricity) invested by the magnetic field will produce a magnetic field-induced internal variable, in the same way that an electrical generator produces electricity by turning an electrical winding in a fixed magnetic field. This current flowing inside the object, in turn, produces a magnetic field with a polarity that tends to oppose the field produced by the coil transmitter.
Receiver: a second electric wire wrapping in the searches, the receiver coil is built (according to different methods) in such a way that the current that should hose due to the proximity with the transmitting coil is effectively canceled. Therefore, the field produced by current flowing in the subject under research head will scroll a current in the receiving coil that can be amplified and processed by the electronics of metal detectors without being covered by more intense current generated by the transmitter coil.
The received signal will be delayed resulting usually compared to the transmitted signal. This delay is caused by the tendency of the conductor found to prevent the stream (resistance) and the change in the direction of the current (inductor). We call this delay “phase shift” . The greater phase shift will be caused by metallic objects that are primarily inductive; large, thick objects, made of excellent conductors such as gold, silver and copper. Small phase shifts are typical mostly resistive object: small, slim or those composed of low-conductivity materials.
Some material little or not at all can still cause a strong signal picked up by the receiving coil. Are the “ferromagnetic” materials. Ferromagnetic substances tend to become magnetized when subjected to a field, such as a paper clip becomes magnetized temporarily if raised with a magnet. Several soils and Sands contain small granules iron ores that make them appear much the ferromagnetic metal detector. Cast iron (nails) and steel objects (bottle cap) show both electric and ferromagnetic properties. What we just said refers to the function of a metal detector “at the induction Balance” or “INDUCTION BALANCE IB”, sometimes referred to as “VLF Very Low Frequency (below 30 kHz). This is the most used technology at the time.
how a metal detector works simple
Discrimination: As the signal received from any metallic object shows a characteristic phase shift (phase shift), you can classify different types of objects and distinguish between them. For example, a silver coin causes a phase shift a lot bigger than a tear of aluminium cans, so that a metal detector can be set to sound on a coin of silver and remain mute on a rip of Tin and also show the target identification on an or WT or on a display. This process of differentiation between metal targets is called “discrimination”.
The simplest form of discrimination allows a metal detector to provide an audio response when it detects a target whose phase shift exceeds a certain threshold (usually presettable feedback). Unfortunately, with this type of discrimination, the tool does not report some coins and jewelry if the threshold is set at a level which prohibit waste aluminum foil as tears of cans and bottle caps. A very useful function in a metal detector is the “NOTCH DISCRIMINATION”. With this system it is possible to insert into the range of discrimination a bell-shaped filter, so that you only accept the targets falling within this Bell and refuse the objects to the left and to the right of it. In more sophisticated metal detectors you can preset these notch and set them to accept or decline.
A metal detector can provide a numerical reading, an indication on a WT or other view types to identify the target detected. This function is called VISUAL DISCRIMINATION INDICATOR or VDI. Metal detectors with this feature have the advantage of providing more detailed information on the type of object found in relation to the single audio response.