How do metal detectors commonly used in security work together? How is it made?

You know the metal detector dangling around you at the security check.

What is the principle?

Clause. 1. Workers wrap copper wire coated with insulating nylon at both ends of the plastic spool, and the number of loops is also fixed. Then wrap a layer of polyester tape around the outside of the ring to prevent it from falling apart. Small metal detectors require the use of pure iron.

Placing it inside the spool enhances the strength of the magnetic field generated by the coil. Without it, the coil would need to be enlarged several times over.

Clause. Second, the next step is to solder the coil with the circuit board, and then solder a vibration motor. A microprocessor is integrated into the circuit board that processes and reacts to the signals emitted by the coils.

The coil and board are then placed in a plastic housing and secured in place. Workers connect the circuit board to a power supply to calibrate the magnetic field generated by the coils, and then attach a slide cover to the detector for switching. Now it's time to assemble it and put it on a prominent label.

The final step is to put batteries on it and a hand-held metal detector is made.

Clause. 3. Another metal detector used for treasure hunting has a larger coil, in fact it has two coils, one for emitting a magnetic field and one for receiving a signal. Such a design allows you to detect only the type of metal you want to find.

Next, they place a circuit board in the coil housing, and a cable is connected from this housing to the probe head, and the components in the probe head process the signal from the coil. Then they began to install the circuit board, and after powering him up, the worker could calibrate the coils on the board to determine exactly whether the test body he found was silver or face.

Clause. Fourth, if everything is in order, install a small speaker on the detector.

Finally, the detector is connected with the handle and arm supporter, and a detector for treasure hunting is completed. Signals from the coil run up the cable to the probe head, where a small processor analyzes the signals to determine if and what kind of metal has been found. If metal is confirmed, the processor will activate the circuit to trigger an alarm and display a message that you have found the big baby.

The working principle of the metal detector commonly used in security is that when it encounters metal, it will starve, and the metal detector will absorb the magnet, and then it will produce a closed loop, resulting in the sound of the metal detector.

This is a magnetic induction phenomenon of metals, and they use the reaction and sensitivity to metals to make judgments.

The metal detector used in the security screening can detect some metal objects and problematic items after scanning the human body. It needs to go through a number of precise processes when it is manufactured.

The working principle of the metal detector is to use alternating current through the coil to generate a rapidly changing magnetic field, so that the magnetic field lines of this magnetic field pass through the metal object and form eddy currents on its surface. The eddy current in turn generates a secondary magnetic field, which in turn affects the original magnetic field and produces a signal that the instrument can receive and identify.

Finally, the signal is processed and amplified to deflect the pointer of the indicator and simultaneously drive the audible indicator to emit an audible signal.

The accuracy and reliability of metal detectors depend on the stability of the electromagnetic transmitter frequency, which is generally used from 8 to 800kHz.

The lower the operating frequency, the better the detection performance of iron; The higher the working frequency, the better the detection performance of high-carbon steel. The sensitivity of the detector decreases as the detection range increases, and the size of the induced signal depends on the size and conductivity of the metal particles.

The belt type is a conveyor belt, and the food is placed on the belt through the probe, and if it contains metal impurities, it will alarm to stop or exclude. The pipeline type is mainly a free-fall type, where the food falls freely, and it will alarm and then discharge after the probe.

The working principle is simply the principle of electromagnetic induction, also known as the principle of eddy current induction.

Metal detectors are generally lightweight and consist of only a few components:

1.Stabilizer (optional) – Keeps the device stable while scanning back and forth with the detector.

2.Console.

Contains circuits, control mechanisms, speakers, batteries, and microprocessors.

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Courtesy of electronics.

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GTI1500 Metal Detector.

Most systems will also have a socket for connecting the handset, and some will place the console underneath and the lever and a small display unit on top.

Metal detectors are easy to operate. Once you've turned on the detector, simply let it slowly move over the area you want to search. In most cases, you'll use a coil (search probe) to scan back and forth above the ground in front of you.

If you sweep past the target, the detector will emit a signal that you can hear. More advanced metal detectors are equipped with displays that accurately identify the type of metal found and the depth at which the target is buried underground.

The metal detector uses the principle of electromagnetic induction to generate a rapidly changing magnetic field by using a coil with zhidao alternating current. This magnetic field can induce eddy currents inside a metal object. The eddy current in turn generates a magnetic field, which in turn affects the original magnetic field and causes the detector to beep.

The accuracy and reliability of specialized metal detectors depend on the stability of the electromagnetic emitter frequency, which is generally used from 80

TO800kHz operating frequency. The lower the operating frequency, the better the detection performance of iron; The higher the working frequency, the better the detection performance of high-grade carbon steel. The sensitivity of the detector decreases as the detection range increases, and the size of the sensing signal depends on the size of the metal particles and conductivity.

Metals have a reflective effect on electromagnetic waves, and when the electromagnetic waves emitted by metal detectors reach the metal surface, they are reflected and received by metal detectors, so the existence of mines is known.

1. The metal detector is used to detect metal, as long as there is metal, it will alarm, and it is used to detect electronic communication equipment in the college entrance examination to prevent candidates from cheating.

2. According to the Measures for Handling Violations in National Educational Examinations, candidates "take the test with materials related to the content of the test or electronic devices that store materials related to the content of the test"; "Carrying a device with the function of sending or receiving information" can be considered as cheating in the test, and the results of each stage and subject of the test registered for are invalid.

3. It is composed of a metal detector and an automatic rejection device, of which the detector is the core part. As soon as the metal impurities enter the magnetic field region and the magnetic field is disturbed, this equilibrium is broken and the induced voltages of the two receiving coils cannot be cancelled out.

4. The induced voltage that has not been offset is amplified by the control system, and an alarm signal is generated (metal impurities detected). The system can use this alarm signal to drive an automatic rejection device, etc., to remove metal impurities from the production line.

If ferromagnetic metals appear near the metal circle, then the original magnetic flux of the metal circle will be greatly affected, and once there are non-ferromagnetic metals, then eddy current effect will be generated in the electromagnetic field area, which will also change the original magnetic field distribution. The detector is also equipped with a sensor that sounds an alarm when it detects a change in the magnetic field in the metal ring and the surrounding area, alerting people to the presence of metal underground.

Because the principle of such a metal detector is relatively simple, the "entry threshold" is low, and the sensitivity, working power and accuracy of its electromagnetic transmitter are very limited, so it is not too high, ranging from the simplest few hundred yuan to tens of thousands of yuan, and the corresponding detection depth is not enough, generally within half a meter, there are some good performance, expensive private metal detectors can detect about 1 meter of space underground. Therefore, it is basically impossible to use these detectors to find the "treasures" in the tombs, one is that the detection depth cannot be reached; second, there is nothing that can be done about non-metallic "antiques"; The third is that it is difficult to distinguish between the detected metals, and sometimes it takes a lot of effort to detect and excavate, which turns out to be just iron nails, steel plates, cans and other items, and sometimes find severely corroded metal coins, which generally do not have much value.

When the probe of the instrument sweeps over the human body (object), if it makes a low sound, and the probe stays above the sound, the sound will gradually disappear, and it can be judged that it is a small piece of metal, such as a belt buckle, zipper, etc. If the sound is high-pitched, and the sound is still continuous even if the probe is stationary, it must be a large piece of metal, such as a dagger, pistol, etc.

The TD-140 is a small handheld metal detector that is easy to use, does not require any adjustment controller, responds quickly to metal objects, and has simultaneous audible and LED illumination. Detects small metals with clear lower frequency tones, large metals with clear lower frequency tones, and large metal objects with high tones.