Modern engineering developments never cease to amaze. Russian developers have created magnetic micro-earphones that are invisible to others, provide high-quality sound, and at the same time allow you to hear everything around you.
Initially, the device was developed as hearing equipment, but later it began to be widely used in other areas. Reviews of magnetic earphones indicate their enormous popularity where a person needs to receive information without other people noticing:
No wired or wireless headset can boast such a list of advantages. It is the absence of wires that makes them indispensable during exams, business negotiations and speeches. The device is inexpensive, so anyone can buy a magnetic earpiece.
The set of micro-earphones includes a headset and a miniature micro-speaker. The earphone is a thin round-shaped magnetic plate that provides mechanical sound vibrations as a result of converting the energy flow of an external magnetic field. In other words, the signals transmitted by the induction loop are transmitted to a person by microvibrations, which he mistakes for normal sound.
Job microdynamics does not require additional power and microcircuits. The main shell is the ear, and the human eardrum is used as a membrane. To use it, the earphone must be placed in the ear canal using a special injector. Basically, the equipment operates for up to 2 hours, but some models operate for about 5 hours.
Reinforcing loop is the link between the microspeaker and the phone. It consists of a coil, as well as a microphone and an amplifier. Through it, the mobile phone signal enters the antenna, and from there the sound enters the microspeaker. With the help of a reinforcing loop, opponents can communicate with each other. Modern technologies completely eliminate extraneous external noise.
The magnet transmits sound to the eardrum and vibrates it. Therefore, outsiders will never be able to recognize the carrier of the magnetic microdynamics, even if they are nearby. The charger is connected separately, is small in size, and easily fits in your pocket. Expensive device models have a longer operating period and a more sensitive microphone.
Let's look at how to insert a device point by point:
Standard models of micro-earphones are 1 cm long and are placed in the ear cavity so that they are completely invisible to others. But, due to the fact that each person’s ears have individual characteristics, the headphones are located inside the ear differently.
After installation, you need to make sure that the tail of the fishing line is not visible and is in the ear canal. For girls and guys with long hair, hiding the presence of a magnetic earpiece is quite simple and does not pose any particular problems.
The bluetooth adapter located on the neck is easier to hide under clothing. Therefore, you should give preference to shirts and blouses with high collars.
Advantages . Charging and connection procedure.
We will tell you in the next section what types of devices are used to take exams. How do they differ in their operating principle?
Advantages of micro headphones:
The dimensions of the magnetic earphones are clearly shown in the photo.
Disadvantages of micro-earphones
The device should not be used every day, otherwise it may cause hearing loss or perforation of the eardrum. Before use, the ear canal must be perfectly clean, and only one person should use the device, since using a micro-earphone by several people can cause infection or fungus.
In case of use sound muffler which tries to introduce any device into the resonance mode of its sound waves, ear injury may occur.
People often wonder if their hearing gets worse after using a device. But, if you follow the instructions for working with magnetic earphones, then any health problems can be easily avoided.
Bluetooth and hands-free headsets create a fairly powerful magnetic effect, which can reach 12 volts. Sound vibrations occur directly on the eardrum, which is why headaches may occur after using them. Experienced otolaryngologists recommend using magnetic earphones for no more than 2 hours, otherwise it may cause hearing problems.
For instructions on using a magnetic earphone, watch the video:
Contraindications for use
Since the design of the micro-magnet earphone is quite simple, it is quite possible to make it at home.
The advantageous difference between magnetic analogues is the ability to operate these devices without replaceable batteries.
The main purpose of any micro-earphone is to receive an electromagnetic signal and then convert it into sound waves that are perceived by the human ear.
Thus, the main elements of this device are:
In order to obtain high quality sound in the presence of a rather weak electromagnetic signal, it is necessary to place the transmitting antenna as close as possible to the receiver.
A capsule micro-earphone contains all the necessary elements, including a signal amplifier, which requires a power source.
The design of magnetic models is much simpler, although the principle of operation remains the same. The signal receiver is magnetic a cylinder of very small diameter (from 1 to 3 mm), capable of responding to changes in the electromagnetic field mechanical vibrations.
These vibrations, of course, are very insignificant, but due to the fact that the micro-earphone is located close to the eardrum, the human ear perceives them as sound.
Thus, the human hearing organs are used as a speaker in a magnetic micro-earphone, and the amplifier is part of the transmitting headset.
Thus, magnetic micro-earphones do not require their own battery.
A 9-volt Krona battery, which is used to power the amplifier if necessary, is connected to the headset.
Manufacturing companies use a special alloy to make magnetic cylinders. Magnets obtained from it are called neodymium.
They are distinguished by much stronger magnetic properties than conventional hard magnetic materials.
Niodymium magnets are sold in electronics stores, radio markets, and also on the Internet. Recently, their selection has expanded significantly. You can buy a magnet of almost any shape, size and weight.
It is possible to make a magnet for an earphone without batteries yourself:
How to choose? What to look for when purchasing?
In the next one we will tell you how hidden communication devices work.
How to properly insert an earphone into your ear, read the link. Some features of installing receivers of various types.
After completing the work, you can check the magnetic properties of a micro-earphone without batteries, made by yourself, using a magnetic stick (pictured).
To avoid damaging the eardrum, the weight of the finished device should not exceed 1 gram; scales will be needed to control it.
When performing work safety glasses must be used, since metal dust can be dangerous to the eyes.
Particular attention should be paid to the absence of sharp edges on the finished device., scratches, chips or other surface damage.
If you want to add a homemade induction loop to a self-made micro-earphone without batteries, you can do this in three ways, presented in the video:
Installing homemade magnets is no different from the standard procedure.
You just need to first make sure once again that the surface of the device is impeccably smooth, and its dimensions and weight meet safety requirements.
Thus, making a magnetic micro-earphone that works without a battery at home is quite possible.
However, this process is quite labor-intensive, in addition, the risk of eardrum damage increases when using homemade devices.
Therefore, it is still better to use factory-made micro-earphones, especially since their price is not so high.
Wireless technologies make our lives easier, brighter, more comfortable. One of these wireless devices can make life a lot easier for students. As you might have guessed, we are talking about a wireless earpiece. You can buy such a device, which is expensive, or you can make it yourself, which is cheaper and sometimes better quality.
1. Chinese radio
2. Mobile phone
3. Hundsfree for this phone model
4. TEM-1958
5. Capacitor 0.1mF
6. Resistors 10kOhm, 43kOhm and 560kOhm
7. Bipolar transistor BC847 - 3 pieces
8. Coil 70-100 turns
9. Battery 337A
10. PEV-2 0.05
11. Flesh-colored heat shrink tube
12. Autoplasticine
13. Sealant
14. Coil from a car relay or wire with a diameter of 0.1mm
15. Gypsum fiber sheet
16. Glue
17. Hairdryer, lighter or candle
18. Tweezers
19. Scalpel
20. Sandpaper, needle file.
21. A piece of thick fishing line
22. Soldering iron
23. Wire cutters
24. Gloves
The device consists of 3 parts:
1. Transmitter, also known as an amplifier.
2. Inductive loop (external loop antenna).
First we make a transmitter
1. We buy the cheapest Chinese radio without a speaker, with automatic channel search. The circuits in different models are almost identical, so any one will do.
2. We disassemble the case.
a. We remove pins 2, 4, 5 from the microcircuit. 
b. Find the middle contact of the headphone plug. We cut off the path leading to it. Will connect here external loop antenna.
c. We solder a wire from hundsfree to the two outer contacts of the volume control (instead of the headset earpiece). 
3. Cut a hole in the radio housing for the hundsfree wire.
4. Put everything back into the body and screw it on.
5. The amplifier is ready.
About the Hundsfree wire
Hundsfree will serve as a connection between the phone and the radio, no special modification is required.
1. Cut off the earphone.
2. Instead of an earphone, solder an amplifier.
If you need a microphone.
3. Let's look at the hundsfree button.
4. Take out the microphone.
5. We connect it to a separate wire.
Making an inductive loop (external circuit)
1. We make a mandrel for the calculated diameter from a gypsum fiber sheet.
2. Remove the coil with wire from the relay.
3. We wind, making sure that the wire is laid correctly. 
4. We wind the required number of turns.
5. Secure it here and there with drops of glue.
6. We disassemble the mandrel.
7. Remove the loop.
8. We wrap the workpiece with the same wire in a spiral.
9. Solder the wire to the workpiece.
10. We reinforce the connection point by wrapping a thicker wire.
11. Prepare a mold of the required diameter from plasticine:
a. We take guides of the same height;
b. Cable diameter 6-7 mm;
c. Prepare the forming surface;
d. Mark the required diameter on the plasticine;
e. We press the wire, shaping the surface;
f. Checking the diameter.
12. We design the place of adhesion.
13. Fill the form with sealant.
14. Place the workpiece in the mold.
15. If necessary, add sealant. Do not allow bubbles to form.
16. Leave for a while. 
17. We get a wire filled with sealant.
18. Trim off the excess.
Making a micro earphone
3. Printed circuit diagram, consists of two parts.
a. Main board: transistors V1-V3 and resistors 10K and 43K.
b. Second: 0.1mF capacitor and 560K resistor. 
4. Carefully grind down the surface of the board from the back side.
a. We use coarse sandpaper, sanding to a minimum, but do not overdo it.
b. Fine sandpaper or file carefully polishing it up surface.
5. We begin soldering the elements according to the diagram. 
6. We glue the finished boards with reliable glue, joining them together.
7. We solder the junction, this is the junction of the capacitor with the emitters of the transistors.
8. We remove the protruding edges with a scalpel!
The result should be something like this: 
9. Now we take a coil with an enameled conductor. 
10. Winding 70-100 turns on TEM and solder its ends to the boards. For reliability, drop a little glue onto the reel.
The result should look like this: 
11. We make the battery holder from tin, for example from an old battery, and material for circuit boards.
a. We cut out the main part of the holder body from a battery, which is terminal "+".
b. Cutting out a circle diameter 6mm from material for making circuit boards.
c. Sand the surface with a file or sandpaper.
d. The result is a “-” terminal.
12. The holder will look like this.
13. Solder the “+” terminal to the right contact of the TEM, make sure so that it does not come into contact with the body.
14. We connect the second contact of the TEM to the circuit.
16. Add missing connections with enameled conductor.
17. We insulate the conductor so that it does not short out. To do this, pour Chinese glue in the places where it passes.
a. Place the battery in the holder.
b. We heat the tube with a hair dryer, lighter or candle.
c. We clamp the heated tube from the battery side with tweezers.
d. We remove excess with a scalpel. 
19. Attach a piece of fishing line to make it easier to remove the earpiece from the ear.
1. When using conductor for winding TEM of larger diameter Self-excitation of the earphone may occur, causing high frequency squeak.
2. A slight hiss in the earphone indicates its correct operation.
1. Select Hundsfree for a specific phone model to avoid problems with sound.
2. The earphone must be miniature, so make the board carefully and carefully.
3. It is better to solder on a metal surface that absorbs excess heat so that the traces do not move away from the board.
4. Automotive clay is very dirty, use gloves.
Quite often there are cases when students are forced to pay money for a session, and even after they answer all the questions posed, teachers express their dissatisfaction and so on. Therefore, if you want to avoid such difficulties, then before the exam session you can take care of purchasing a micro-earphone that will help you quickly overcome this period.
Micro-earphones are usually understood as capsules of minimal size, the main purpose of which is to provide hidden wireless communications.
Currently, the following elements can be found in such a kit:
Typically, the headset is attached to the bottom of clothing, and then it is connected to a mobile device via Bluetooth.
In general, the operation scheme of micro-earphones is not complicated, since for this you will need a mobile phone with Bluetooth, to which the headset will be connected in the future, and then it is inserted into the ear. Now you can go to the classroom with complete peace of mind.
Of course, such prompters bring a lot of benefits to students, even when they are in another city. When you have chosen your ticket, you must very quietly communicate all the questions presented there through the headset. Everything else depends only on the assistant, because it is he who will dictate the correct answers. As a rule, others cannot notice this, because any signals are transmitted through an invisible earphone located in the auricle. All that remains for the examinee is to write down everything that he hears in the headphones.
Thus, hidden earphones can be called the most excellent option for cheat sheets. It has been proven many times that the device is highly effective.
With the help of wireless technologies, the life of modern people has become not only more colorful, but also more comfortable. Thanks to one such invention, student life became easier.
Now such devices are sold in huge quantities, although the cost of some of them is quite high. Let's look at how to make a magnetic earpiece with your own hands.
If you want to make your own headphones, then for this you need to prepare:
This device includes immediately three main parts:
You should start with creating a transmitter, and for this it is recommended to perform the following steps:
Now it's time to consider Hundsfree wire, which is designed to connect a telephone and a radio, but it does not require any additional modifications.
Quite often a microphone is absolutely necessary, so it is recommended:
For creating inductive loop or outer contour, you need:
The step-by-step process of assembling micro-earphones with your own hands is shown in the video:
Modern experts give a number of valuable advice:
If you are using an earphone and hear a slight hissing in it, then you should not be afraid, because this effect is an indicator of proper operation.
In addition, when a conductor is used to wrap a large diameter TEM, the process of self-excitation of the headphones often begins, which is why a high-frequency squeak appears.
Such a micro-earphone was made the other day at the end of the session. There are a lot of exams, and it’s somehow not realistic to study and work at the same time, so please understand correctly - I’m not lazy, I just didn’t have time to study. Over the weekend, a compact micro-earphone was made. The device is very compact, since SMD components were used, their soldering was done with an ordinary 30-watt amateur radio soldering iron (under a microscope). The micro-earphone circuit is quite simple; it is a low-power low-frequency amplifier.
The amplifier is assembled with only three transistors and does not contain scarce components. You can also use microcircuits with low-voltage power supply (TDA7050), only the supply voltage needs to be doubled.
The micro-earphone is powered by only one battery with a voltage of 1.2 volts. The circuit was assembled by surface mounting; using a printed circuit board would increase the dimensions. Any miniature head with a resistance from 32 to 120 Ohms can serve as a headphone.
The receiver circuit contains 70-100 turns of thin enameled wire (diameter around 0.06-0.08 mm), the amplification part is wound, and the amplifier is pre-insulated.
The wire is wound in bulk. For reliability, the micro-earphone can be placed in a heat-shrinkable tube or coated with silicone. This solution provides stability during falls, etc.
The transmitting part consists of a magnetic antenna. This is, in fact, a contour, has a diameter of 30 cm, and is worn around the neck. The circuit consists of 50 turns of wire 0.3-0.6 mm. After winding, it is advisable to isolate it for comfortable and discreet wearing. From the outside, such a contour should look like a necklace, otherwise there is a danger of being noticed, you yourself know the consequences very well...
The ends (leads) of the transmitting coil can be directly connected to the phone's headphone jack. During a conversation, sound will be transmitted by induction directly to the ear, without any wires!
