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Basic Principle of Portable Metal Detectors
Basic Principle of Portable Metal Detectors

The basic line control instruments by the oscillator, phase shift and amplitude bridge, selected frequency amplifier , detector ultra-low frequency amplification emitter fit one-shot swing, power supply.

Portable metal detector (grounds 15kHz oscillator generates a sinusoidal voltage detection coil fed detection coil by a master transmitter coil) basic principle is important. It includes two vice- ring and the input transformer, output transformer. Vice- ring located on the main transmitter groups on both sides of laps, lap distance equal to the primary transmitter and symmetrical, and cross-linked with each other to form a differential coil. When 15 kHz sine wave oscillator generates a sinusoidal alternating voltage of the transformer is fed through the input master transmitter coil, thus producing 15 kHz alternating magnetic field, and two pairs of the cutting ring in the main loop by transmitting a large alternating current.

Because of the two vice- lap main launch yet another lap distance symmetrical cross chain, while the induction of an equal magnitude but opposite direction (phase difference of 180 °) of the EMF 15kHz offset each other ( due to the relationships that we cannot process the two deputy circle the main circle done completely symmetrical, and shielding materials outside influence, there is always a mV output transformer unbalanced signal output level , and we want it as small as possible ). When no X-Ray baggage scanner into the circle , only a faint 15kHz signal output amplitude imbalance, this signal after amplification by a DC voltage detector becomes blocking capacitor being blocked, you cannot enter the post-amplifier, then the instrument still in a relatively stable state.

Once the metal into the detection coil, metal is at 15kHz alternating magnetic field, generated EMF , eddy current phenomena, so the relative balance detection coil is destroyed, and produce low-frequency pulsating electrical potential difference, this pulsating potential difference is set out in the original such as the amplitude imbalance signal input to the amplifier amplifies. When you buy metal detector, according to portable metal detector, x-ray security machine through the first-stage amplifier, 3000 a magnitude has been amplified 4000 times, and then into the detector to remove the useful signal from the low-frequency amplifier unbalanced signal sending trade deficit, but also get more than 1000 -fold magnification. At this point the signal from the original metal microvolt signals become amplified by several orders of magnitude volts, and after reaching the trigger voltage level trigger, the trigger work led relay, an alarm signal, and control objects required for automatic control. For example, cut off the power supply load, lit lights, sound signals, etc., based on these, we can determine the presence or absence of metal.

Portable metal detector, which possesses security screening system, is designed to detect people or objects carrying metal objects. It can detect the parcels, x ray baggage scanner price, mail, etc. within the fabric brought weapons, explosives or small metal objects people carry. You should know particularly sensitive to the appearance of its surface make operation simple and easy. Superior ring sensor type hand probe. See more at:X-ray baggage Inspection system