The principle of the metal detector is also very simple. It uses the high-frequency current connected to the metal coil, which is equivalent to a hollow coil that can generate a magnetic field. If a metal object appears in or near the hollow coil, these alternating magnetic fields will induce eddy currents on the metal, which will affect the magnetic field in the hollow coil. At this time, monitor the changes of these magnetic fields, You can sense whether there are metal objects nearby!
According to the detection principle, metal detectors can be divided into electromagnetic induction type, X-ray detection type and microwave detection type. Of course, X-rays are transmission type, which need to be transmitted at one end and received at the other end, or there is an X-ray reflecting surface. For example, when performing dental radiography, a reflecting surface needs to be set behind the back of the tooth. Therefore, common metal detectors generally refer to electromagnetic type. The following two excellent metal detector principles are recommended:
Very low frequency (VLF) metal detector, also known as inductive balance metal detector
This is the most popular metal detector at present. It has two coils, one is the outer ring coil for transmitting, and the other is the inner ring coil for receiving. The receiving coil can be set with a filter circuit to filter out the interfering magnetic field of the transmitting coil, but it will not induce the electromagnetic wave emitted by the underground metal object after the outer ring coil is launched. After the electromagnetic wave is amplified by the inner ring receiving coil, It can be displayed on the display screen in the form of alarm or electromagnetic wave numerical characteristics, and a depth can be roughly determined according to the value.
