In our time, many people are passionate about finding buried treasures, and sometimes even simple scrap metal. For some, this activity has become an interesting pastime, and for some, it has become a means of earning money.
The first sample of an industrial metal detector was created in the 1960s and found wide application in the mining and other special operations.
Devices are used in demining, to find weapons, in the exploration of geophysicists and archaeologists, when searching for treasures, and also to find foreign bodies made of metal in food. In the construction industry, they are used to detect reinforcement in concrete blocks and pipelines in walls. Metal detectors also began to be used by miners and prospectors. And the improvement of the device made it possible not to resort to excavations when finding gold.
Many people have become interested in this device over the past decades. The search for treasures and scrap metal has become a popular hobby. Some, for example, walk with such a device on the beach, hoping to find a valuable thing.
Who invented the metal detector
It is difficult to give an unambiguous answer to the question of which device was the first, since at about the same time many inventors in different parts of the world carried out their own developments of the named unit.
But if we talk about one specific person who can be considered the ancestor of the device, then this is undoubtedly the English geologist and mining engineer Fox. He discovered the property of the passage of electricity through metal ores and objects. Around 1830, he carried out the development of the first unified locator, which included a battery, several metal rods and wires of suitable length.
First methods for finding metal
The first search method was as follows: one rod of metal lay in the ground, where the ore was supposed to be. It was connected to one terminal of the battery. The other terminal was connected to the floating wire. Metal rods were hammered into the ground at different points and sequentially touched the wire. Sparks appeared when a metal object was found.
In 1870, two separate rods were already used in the device. The wire connected through the battery was lowered into the ground. On contact with metal, an alert bell sounded.
Adaptation "Pirate"
And now we will look at modern devices. One of them - "Pirate" - a metal detector that operates on the conductivity of electricity, inductive and magnetic properties of the metal. By the way,the device got its interesting name from the inventors: PI is the impulse principle of its operation, RAT is an abbreviation for Radio Cattle (the website of the inventors).
Metal detector "Pirate", the photo of which is presented in this article, has a unified design. It includes a generator that produces an alternating current that passes through a coil with a magnetic field. If the metal conducting the current is too close to the coil, then the vortex flows will be directed to the metal. This contributes to the formation of an alternating magnetic field in the metal. To detect the latter makes it possible to use another coil to measure the magnetic field.
Device Benefits
"Pirate" (metal detector) has a simple design and a unified setting, does not contain the elements specified by the program, which many radio amateurs are so afraid of. The device is great for beginners. And it should be remembered that he cannot distinguish between metals.
Pirate metal detector, the printed circuit board of which is represented by the NE555 chip (domestic analogue of KR1006VI1) does not contain expensive or hard-to-get parts. Its technical parameters are in no way inferior to foreign analogues, the price of which reaches 300 USD. e.
And the main advantages of this device over others are stability and response to metal from a long distance.
The unified "Pirate" (metal detector for beginners) has certain technical characteristics. His meals are 9-12Volt, and the level of energy consumed is 3-40 mA. The device senses objects up to 150 cm in size.
Design
Transmitting and receiving are the main components that make up the Pirate metal detector. The printed circuit board, which is the NE555 model, and the IRF740 high power switch are included in the transmitter assembly. And the receiving unit is assembled on the basis of the K157UD2 chip and the VS547 transistor.
The coil is wound on a mandrel with a diameter of 190 mm and contains 25 turns of PEV wire 0.5.
The NPN bipolar transistor has replaced the T2 model and has a voltage of at least 200 volts. It can be taken from an economical lamp or a device for charging a mobile phone. As a last resort, T2 can be replaced with KT817.
Any kind of NPN circuit transistor can be used as T3.
A correctly assembled device does not need additional configuration. You may have to resort to using a resistor R12 so that clicks during movement appear in the middle position of R13.
If you have an oscilloscope, you can control the duration of the control pulse at the T2 gate and the frequency level of the generator. The optimal pulse duration is 130-150 µs and the frequency is 120-150 Hz.
How to operate the appliance
After turning on the “Pirate” device (metal detector), wait 15 or 20 seconds, after which the sensitivity control is used to set the position at which clicks are heard during movement. This will serve as an indicator of the maximumsensitivity.
The device has a unified control system, so acquiring skills to work with it is not so difficult.
Metal detector "Pirate" do-it-yourself
Many people ask themselves: how to make a Pirate metal detector on your own? Assembling such a unit is within the power of people with basic knowledge in the field of electronics.
The "Pirate" impulse metal detector has the most common and easy-to-copy design. The device contains a number of components and an easy-to-use search coil. If its diameter is 280mm, it can detect objects between 20cm and 150cm in size.
Making a Pirate metal detector with your own hands is not a difficult task, which is a huge advantage of this device. Assembly components are accessible and easy to find. They are quite cheap. You can buy them at the radio parts store or at the market.
List of required parts for manufacturing
Let's try to assemble the Pirate metal detector with our own hands. Detailed instructions will help even inexperienced radio amateurs to do it without errors.
The device has two schematic modifications. In the first case, the NE555 microcircuit is used (the domestic analogue of the microcircuit is KR1006VI1) - a timer. But if you could not purchase this component, then the authors provide another version of the circuit based on transistors.
But it is still recommended to assemble the device based on the firstcircuit, as it has more stability in operation.
When assembling based on transistors, you should choose the desired frequency and duration, since they have a rather large spread in technical characteristics. For this purpose, resort to the use of an oscilloscope.
Instrument circuit board
The home-made metal detector "Pirate" has several options for wiring the printed circuit board, but most often they use the board of the Sprin Layot series.
After soldering, power is connected to it. For this purpose, any power source with a voltage indicator of 9-12 Volts will be used. You can resort to using batteries "Krona" (3 or 4 pieces) or a battery. The use of one "Krona" is not recommended, as this will cause a rapid voltage drop, which, in turn, will cause the device's settings to freeze permanently.
Production of coils for metal detector "Pirate"
Like other models of impulse devices for finding metal, the device is undemanding in terms of accuracy in the manufacture of the coil. It is quite acceptable to use the one that is wound on a mandrel with a diameter of 190-200 mm - 25 turns. In this case, a winding enameled wire with a cross section of 0.5 mm is used.
The turns of the coil are wrapped with insulating tape or adhesive tape. By the way, to increase the depth of the search for the device, you can resort to winding the named part, with a diameter of 260-270 mm, 21-22 turns with the same wire.
Attachment Coilis fixed in a rigid housing, which must be made of, for example, plastic. This is necessary in order to protect the device from hitting the ground or grass during operation of the unit. Such a case can be purchased in online stores. In general, when making search coils, the use of metal parts is not recommended.
The conclusions of the mentioned part are soldered to a stranded wire with a cross section of 0.5 - 0.75 mm. Ideally, this is two independent interlaced wires. Your device is ready!
Reviews
The reviews available on the Pirate metal detector indicate that it has become very popular with users. According to them, the device has a high degree of functionality, and finds things made of metal in a short time and without errors. It is easy to apply and does not feel in the hand.
The finished device is assembled from several parts that are easily assembled. The lower part is its base. The system of work with the device is extremely clear. Setting up a metal detector "Pirate" is not difficult.
