How they differ from conventional detectors and where they are best used, let's look at examples.
Principle of operation
Any metal detector generates a magnetic field around the transmitter coil. Thanks to this, a magnetic flux also appears at the target under the coil, which is caught by the coil’s receiver. This magnetic flux is then converted into visual information on the screen and into an audio signal.
Conventional ground metal detectors (VLF) generate a constant current in the transmitter coil, and changes in the phase and amplitude of the voltage at the receiver indicate the presence of metal objects. But devices with pulse induction (PI) differ in that they generate a transmitter current that turns on for a while and then turns off abruptly. The coil field generates pulsed eddy currents in the object, which are detected by analyzing the attenuation of the pulse induced in the receiver coil. This cycle repeats continuously, perhaps hundreds of thousands of times per second.
Pros of metal detectors with pulse induction
1. Detection speed does not depend on the material between the metal detector and the target. This means that the search can be carried out through air, water, silt, corals, and various types of soil.
2. The sensors are highly sensitive to all metals and do not react in any way to high levels of soil mineralization, hot stones and salt water.
3. You can search for metal objects and find them at greater depths; this works especially well on mineralized soils.
4. There will be no interference in mineralized soils, salty sand, salt water, and the performance will be higher than VLF detectors.
5. Pulse induction metal detectors have been specially designed to find gold objects, even very small ones (nuggets, chains).
The disadvantages of metal detectors with pulse induction may be not very good discrimination and high price.
Where do pulse induction metal detectors perform best?
The pulse repetition rate (transmitter frequency) of a typical pulse induction metal detector is approximately 100 hertz. Different MD models use frequencies from 22 hertz to several kilohertz. The lower the transmission frequency, the greater the radiated power. At lower frequencies, greater depth and sensitivity for detecting objects made of silver are achieved, but sensitivity to nickel and gold alloys decreases. Such devices have a slow response and therefore require very slow movement of the frame.
Higher frequencies increase sensitivity to nickel and gold alloys, but are less sensitive to silver. The signal may not penetrate as deep into the ground as at lower frequencies, but the coil can be moved more quickly. This allows you to check a larger area over a given period of time, and such devices are also more sensitive to the main beach finds - gold items.
Thus, it is best to use PI metal detectors for beach searching on the coasts of seas and oceans, underwater searching, gold searching, searching in desert and mountainous areas. They are also good at clearing out “knocked-out” areas and during geological exploration.
Top 5 best pulse induction metal detectors:
Metal detectors are used to search for metal in the soil at a certain depth. This device can be assembled independently at home, having at least minimal experience in this matter, or following the clear instructions in the instructions. The main thing is the desire and availability of the necessary tools.
This type of design is designed to search for coins. The process of assembling it is completely simple. However, experience in assembling such a tool is still necessary. The Terminator is able to detect an object even if the target of capture is minimal.
To begin, you should prepare the necessary equipment, namely:
Next, you need to find a diagram broken down into nodes. Now you can make a printed circuit board into which jumpers, resistors, panels for microcircuits and other parts should be soldered in order. The next step is to clean the board with alcohol.. It is definitely worth checking for defects. You can check whether the board is in working condition as follows:
If all actions occurred, then everything was done correctly. Now you can make a coil. It is necessary to prepare a winding enamel wire with a diameter of 0.4 mm, which must be folded in half. A circle is drawn on a sheet of plywood with a diameter of 200 mm and 100 mm. Now you need to drive nails in a circle, the distance between them should be 1 cm.
Next, you can move on to winding the turns. At 200 mm you should make 30 of them, and at 100 - 48. Then the first coil should be soaked in varnish; when it dries, you can wrap it with thread. The thread can be removed, and by soldering the middle, you get a solid winding of 60 turns. Afterwards, the coil must be wrapped quite tightly with electrical tape.. And a 1 cm foil is placed on top, this will be a screen, and more electrical tape is wound on top of it. The ends should come out.
On the second coil it is also necessary to solder the middle. In order to start the generator, you need to connect the first coil to the board. The second coil should be wrapped with a wire of 20 turns, then we connect it to the board. Now you need to connect the oscilloscope minus to minus to the board, and the plus is connected to the coil. Be sure to look at what frequency it will be when you turn it on and remember it or write it down on paper.
Now the coils need to be placed in a special mold so that they can then be filled with resin. Next, the oscilloscope is connected to the board, with the negative pole, the amplitude should reach zero. The coils in the mold are filled with resin to approximately half the depth. When everything is ready, the metal discrimination scale is adjusted.
As parts for the trio metal detector you will need:
If you have these parts, you can assemble the Terminator Pro metal detector yourself.
You can make a metal detector with metal discrimination yourself using the circuit for the Chance pulse device. The process of making a coil is quite simple.
The diagram itself can be found on the Internet. But still, experience in assembling such devices will be useful. Assembling the metal detector should begin with the board.
After the board is manufactured, the microcontroller needs to be flashed. And at the end of the work, we connect the metal detection device to the power supply.
Homemade equipment can be made without complex microcircuits, but using a simple transistor generator. The metal detector will be non-discriminatory. It will detect objects in the ground to a depth of 20 centimeters, and in dry sand - to a depth of 30 centimeters. In this device, the transmitting and receiving coils operate simultaneously.
To begin with, you should take winding enamel with a diameter of 0.4 mm. Fold it so that there are two ends and two beginnings. Next, you should wind from two reels at a time.
Now we need to make transmitting and receiving coils; for this, two circles of 200 mm and 100 mm are drawn on a plywood sheet. Nails are driven in along these circles, the distance between them should be 1 cm. 30 turns of enamel wire are wound onto a large mandrel. Then you should apply varnish to the coil and wrap it with thread, then remove it from the winding and solder the middle. This creates one middle wire and two outer wires.
The resulting coil should be wrapped with electrical tape and a piece of foil should be placed on top, and foil again on top. The ends of the windings should go outside.
Now it’s time to move on to the receiving coil. 48 turns are already wound here. To start the generator, you need to connect the transmitting coil to the board. The middle wire is connected to the negative. And the middle terminal of the take-up coil is not used. The transmitting coil requires a compensating coil, on which 20 turns are wound.
We connect the oscilloscope to the board like this: a probe with a minus to the minus of the board, and a plus probe to the coil. Be sure to measure the frequency of the coils and write it down.
After connecting the coils according to the diagram, they must be placed in a special container and filled with resin. The oscilloscope now sets the division time (10 ms and 1 volt per cell). Now you should reduce the amplitude to zero. We wind the turns until the volt value reaches zero. We make a compensating loop at the coil, which will be outside.
The mold should be filled halfway with resin. When everything hardens, you need to connect the oscilloscope and bend the loop inward. Then twist it until the amplitude value becomes minimal. Afterwards, you need to glue the loop, check the balance, and now you can fill the second half of the container with resin. The reel is ready for use.
Before you begin the repair, you should prepare the following tools:
First of all, you need to dry the coil using an incandescent lamp. And use a utility knife to widen the cracks on it. Squeeze the glue onto a flat surface and mix with a spatula. Apply this substance to the coil. In places of cracks, you can apply more resin. Now you should wait until it all hardens thoroughly. And then sand it, using first medium and then fine sandpaper. This procedure will help smooth out all the unevenness. In this fairly simple way, you can revive the oldest coil from a metal detecting device.
A printed circuit board for this type of equipment can be made and configured independently. The board diagram for Terminator 3 is available on the Internet. Once it is found, you can begin manufacturing the printed circuit board. After that, jumpers, SMD resistors and panels for microcircuits are soldered into it. The capacitors on the board must have high thermal stability.
Before starting work, it is necessary to prepare a device that will accurately measure capacitance and inductance. Now you should take the housing for the reel and make PCB inserts into the ears. Pieces of fabric are used for compaction. The upper surface of the ears should be sanded. The fabric must be impregnated with epoxy resin. When everything is dry, you should sand everything and insert a sealed lead-in, thus making grounding. Next you need to apply a special Dragon varnish.
Now windings are made, which are tied with threads. All windings are placed in a coil and capacitors are glued. Everything can be connected and configured. A housing is required for pouring. Mandatory: there should be no metal nearby. After pouring, the epoxy should be sanded and dried thoroughly. The sensor is suitable for the Terminator 3 and Terminator 4 metal detectors, which are the most popular models of devices.
Many people consider this model of device popular. The positive qualities include:
And the following are identified as negative features:
The search depth of the device is higher than that of other similar models. Basically this is 30 centimeters using the example of a coin.
The metal detector has an operating frequency of 5 to 17 kHz. Its power supply is 12 Volts. Its ground balance is manual.
The circuit of this device is not entirely simple, since it contains two microcontrollers. The diagram can be found on the Internet. The device itself has good characteristics. However, due to the lack of detailed assembly information, difficulties may arise in the manufacture of the device.
“Fun” uses the “frequency meter” principle. The metal detector operates in dynamic mode (reacts to metal only when the sensor moves). There is a sensitivity adjustment. Metal detector with discrimination (selectivity). Using the Zabava metal detector, you can distinguish between signals for small iron objects (nails, nuts, wire, etc.) and signals for objects made of non-ferrous metals. Iron objects with a large surface area are defined as non-ferrous.
Technical characteristics of the Zabava metal detector:
Detection distance (in air):
The program recorded in the microcontroller periodically measures the frequency of the working generator. Analyzing the measurement results, the program detects an increase or decrease in the frequency of the working generator and issues a corresponding signal to the headphones.
CKSEL0, SUT0, SPIEN must be programmed. The rest are not programmed.
The setup consists of setting the signal volume in the headphones using R6.
After turning on the power to the metal detector, you must always press the “reset” button. Before starting work, you need to tune in to the ground in the search area. Set resistor R8 to maximum sensitivity (rotate clockwise until it stops). Bring the search coil to the ground at a distance of 1 - 2 cm (there should be no metal objects nearby) and slightly rocking it in a vertical plane, slowly reduce the sensitivity (rotate the knob counterclockwise) until the signals from the ground in the headphones disappear.
When searching, the coil must be moved above the ground at a speed of approximately 0.5 m/sec, trying to keep the distance from the ground to the coil the same all the time. In most cases, when a metal object is detected, the metal detector gives a double signal.
If the first was a high-frequency signal, and the second was a low-frequency signal, then the found object was made of non-ferrous metal, or iron with a large surface area. If the first signal is low-frequency and the second is high-frequency, then the find is a small iron object.
To determine the exact location of a non-ferrous metal object, you need to raise the coil above the ground, then lower it vertically to the ground at the expected location of the object. If a low-frequency signal is heard when lowering, it means there is no non-ferrous metal under the coil. If the coil drops exactly above the non-ferrous metal, a high-frequency signal will sound. In the same way, you can examine pits, as well as areas heavily littered with small iron objects, rust, coals, etc.
At maximum sensitivity, the metal detector can constantly give false signals. This occurs due to unstable operation of the search generator; the reason may be in C1 and C2, in the coil, or in the fragile design of the rod and sensor.
If false signals occur at sensitivity levels at which the metal detector previously worked normally, this means the battery is low.
Be careful when connecting the battery - it is unacceptable to confuse the plus with the minus, even for a short time. If it is “reversed”, the metal detector may fail.
A device that allows you to search for metal objects located in a neutral environment, such as soil, due to their conductivity is called a metal detector (metal detector). This device allows you to find metal objects in various environments, including in the human body.
Largely thanks to the development of microelectronics, metal detectors, which are produced by many enterprises around the world, have high reliability and small overall weight characteristics.
Not so long ago, such devices could most often be seen among sappers, but now they are used by rescuers, treasure hunters, and utility workers when searching for pipes, cables, etc. Moreover, many “treasure hunters” use metal detectors, which they assemble with their own hands .
Metal detectors on the market operate on different principles. Many believe that they use the principle of pulse echo or radar. Their difference from locators lies in the fact that the transmitted and received signals act constantly and simultaneously; in addition, they operate at the same frequencies.
Devices operating on the “receive-transmit” principle record the signal reflected (re-emitted) from a metal object. This signal appears due to the exposure of a metal object to an alternating magnetic field generated by the metal detector coils. That is, the design of devices of this type provides for the presence of two coils, the first is transmitting, the second is receiving.
Devices of this class have the following advantages:
At the same time, metal detectors of this class have certain disadvantages:
In other words, devices of this type must be configured with your own hands before work.
Other devices are sometimes called beat metal detectors. This name comes from the distant past, more precisely from the times when superheterodyne receivers were widely used. Beating is a phenomenon that becomes noticeable when two signals with similar frequencies and equal amplitudes are summed. The beat consists of pulsating the amplitude of the summed signal.
The signal pulsation frequency is equal to the difference in the frequencies of the summed signals. By passing such a signal through a rectifier, it is also called a detector, and the so-called difference frequency is isolated.
This scheme has been used for a long time, but nowadays it is not used. They were replaced by synchronous detectors, but the term remained in use.
A beat metal detector works using the following principle - it registers the difference in frequencies from two generator coils. One frequency is stable, the second contains an inductor.
The device is configured with your own hands so that the generated frequencies match or at least are close. As soon as metal enters the action zone, the set parameters change and the frequency changes. The frequency difference can be recorded in a variety of ways, from headphones to digital methods.
Devices of this class are characterized by a simple sensor design and low sensitivity to the mineral composition of the soil.
But besides this, when operating them, it is necessary to take into account the fact that they have high energy consumption.
The metal detector includes the following components:
All devices included in the metal detector are waterproof.
It is this relative simplicity of design that allows you to make metal detectors with your own hands.
There is a wide range of metal detectors on the market, used in many areas. Below is a list that shows some of the varieties of these devices:
Most modern metal detectors can find metal objects at a depth of up to 2.5 m; special deep products can detect a product at a depth of up to 6 meters.
The second parameter is the operating frequency. The thing is that low frequencies allow the metal detector to see to a fairly large depth, but they are not able to see small details. High frequencies allow you to notice small objects, but do not allow you to view the ground to great depths.
The simplest (budget) models operate at one frequency; models that fall into the middle price range use 2 or more frequencies. There are models that use 28 frequencies when searching.
Modern metal detectors are equipped with a function such as metal discrimination. It allows you to distinguish the type of material located at depth. In this case, when ferrous metal is detected, one sound will sound in the search engine’s headphones, and when non-ferrous metal is detected, another sound will sound.
Such devices are classified as pulse-balanced. They use frequencies from 8 to 15 kHz in their work. Batteries of 9 - 12 V are used as a source.
Devices of this class are capable of detecting a gold object at a depth of several tens of centimeters, and ferrous metal products at a depth of about 1 meter or more.
But, of course, these parameters depend on the device model.
There are many models of devices on the market for detecting metal in the ground, walls, etc. Despite its external complexity, making a metal detector with your own hands is not that difficult and almost anyone can do it. As noted above, any metal detector consists of the following key components - a coil, a decoder and a power supply signaling device.
To assemble such a metal detector with your own hands, you need the following set of elements:
The metal detector circuit is not complicated, and you can find it either on the vast world wide web or in specialized literature. Above is a list of radio elements that are useful for assembling a metal detector with your own hands at home. You can assemble a simple metal detector with your own hands using a soldering iron or other available method. The main thing is that the parts should not touch the body of the device. To ensure the operation of the assembled metal detector, power supplies of 9 - 12 volts are used.
To wind the coil, use a wire with a cross-sectional diameter within 0.3 mm; of course, this will depend on the chosen circuit. By the way, the wound coil must be protected from exposure to extraneous radiation. To do this, shield it with your own hands using ordinary food foil.
To flash the controller firmware, special programs are used, which can also be found on the Internet.
If a novice “treasure hunter” has no desire to get involved with microcircuits, there are circuits without them.
There are simpler circuits based on the use of traditional transistors. Such a device can find metal at a depth of several tens of centimeters.
Deep metal detectors are used to search for metals at great depths. But it is worth noting that they are not cheap and therefore it is quite possible to assemble it yourself. But before you start making it, you need to understand how a typical circuit works.
The circuit of a deep metal detector is not the simplest and there are several options for its implementation. Before assembling it, you need to prepare the following set of parts and elements:
Nominal parameters and quantity depend on the selected circuit diagram of the device. To assemble the above elements, you will need a soldering iron, a set of tools (screwdriver, pliers, wire cutters, etc.), and material for making the board.
The process of assembling a deep metal detector looks something like this. First, a control unit is assembled, the basis of which is a printed circuit board. It is made from textolite. Then the assembly diagram is transferred directly to the surface of the finished board. After the drawing is transferred, the board must be etched. To do this, use a solution that includes hydrogen peroxide, salt, and electrolyte.
After the board is etched, it is necessary to make holes in it to install the circuit components. After tinning the board. The most important stage is coming. Do-it-yourself installation and soldering of parts onto a prepared board.
To wind the coil with your own hands, use PEV brand wire with a diameter of 0.5 mm. The number of turns and the diameter of the coil depend on the selected circuit of the deep metal detector.
There is an opinion that it is quite possible to make a metal detector from a smartphone. This is wrong! Yes, there are applications that install under Android OS.
But in fact, after installing such an application, he will actually be able to find metal objects, but only pre-magnetized ones. It will not be able to search for, much less discriminate against, metals.
Today, a very promising direction in search instrument making is the development and production of pulse metal detectors. Unlike conventional ultra-high-frequency metal detectors, pulsed metal detectors have a much greater search depth and work great on soils with high mineralization, especially on sea beaches.
In addition to the fact that the pulse metal detector has the best search depth, it also has the highest sensitivity among all metal detectors. Thanks to these characteristics, the search for gold and historical artifacts becomes much more efficient. The chances of finding some valuable small object located at a certain depth increase significantly.
Another undeniable advantage of the Minelab SDC2300 pulse metal detector is its versatility in working with any soil. Sometimes the increased mineralization of the soil creates certain difficulties for searching for any objects using a conventional metal detector. The pulse metal detector does not have such difficulties - it works perfectly both on any type of soil, or in the coastal zone, and in sea water.
I would also like to say that a pulse metal detector is much more effective than other types of metal detectors when working near antennas, power lines and other structures that create electromagnetic interference. The well-designed design of this device allows you to reduce the impact of such interference to a minimum.
When connecting deep coils, a pulse metal detector easily turns into a deep metal detector, allowing you to search for large metal objects at a fairly large depth. However, searching for small artifacts in this case becomes impossible.
Until recently, pulse metal detectors had one significant drawback - they did not have a metal discrimination function. When searching for artifacts, it was difficult or almost impossible to determine what type of metal was in the ground without first digging it up.
However, technology is developing more and more intensively every day, and now pulse metal detectors have also received a metal discrimination function in their arsenal. This circumstance makes a pulse metal detector more preferable for searching for gold compared to other metal detectors.
Thanks to the discrimination function, the Minelab SDC2300 pulse metal detector can now be configured to search for artifacts made of non-ferrous metals. This significantly expands the capabilities of the device and allows it to be used when searching for objects made of non-ferrous metals both in the forest, in the field, in mountainous areas, and in the coastal strip or in flooded areas.
If you are interested in a pulse metal detector, you can buy it at the Treasure Hunter store. Buying a pulse metal detector requires careful study of all its technical characteristics.
There are several options for Minelab GPZ7000 Minelab SDC2300 devices. After viewing all the characteristics you are interested in, you can ask clarifying questions to the online consultant directly on the store page.
We provide a guarantee for pulse metal detectors, as well as for other types of metal detectors. All search equipment, including pulse metal detectors, has certificates of conformity and is delivered anywhere in Russia. All metal detectors in our store are from original manufacturers. We wish you a pleasant shopping and successful search.
