Manufacturing of structural parts and assembly of emitters. Membrane. Lavsan film made from K73-16 capacitors is well suited as a membrane material. In many ways, this is a wonderful base, with the exception of one drawback - its width is only 35 mm, which imposes certain restrictions on the area and shape of the membrane. In capacitors for an operating voltage of 100 V, the film thickness is 4 ... 5 microns.

How to make your own headphones

This is quite enough for an amateur design. Indeed, even with such a thickness of the film, its mass, as follows from, is comparable to the mass of faltering air. The capacitance rating of the capacitor does not matter, it is important that the length of the capacitor body is 48 mm. This is the maximum possible size, and the width of the film removed from such a capacitor is exactly the same 35 mm.

Of course, if there is a possibility of using a film of suitable dimensions similar in its properties, then the task of manufacturing a larger-sized membrane is greatly simplified. However, the option with a capacitor film, although it is problematic from a technological point of view, is quite affordable and requires separate consideration. To do this, you can refer to, where the manufacture of a membrane for TDS-7 phones is described in detail. With regard to this case, the revised part of the description looks as follows. Carefully cut along the capacitor body and take out its “filling”.

We unwind and remove the initial part of the roll 20 ... 30 cm long, where a thick film is used as a dielectric. Further, in fact, the working part of the capacitor begins, which is two films folded together (capacitor plates). Cut off a 15 cm long strip from the roll. Separate the films from each other with a sharp scalpel. The main difficulty is to “catch on” to the beginning of the section of the fused tapes.

Further, to facilitate the process, you can drop a few drops of acetone into the formed gap between the films. After the films are separated, metallization should be removed from them. In this case, you can use ordinary bleach, the process time is 20 minutes.

After that, the films should be thoroughly rinsed, dried and ironed with a hot iron (temperature for wool) through a sheet of paper, it is better just between the sheets in the book. At the exit of the process, we obtain transparent, even, smooth films suitable for work. To obtain the desired size of the membrane in width, the resulting two films must be glued together. In contrast to the method described in the method, in this case, gluing must be carried out with an overlap.

We do it like this.

We put the previously prepared films, as described above, on a flat smooth surface and connect them together with long sides with an overlap of 1.5 ... 2 mm. Holding them in this position and bending one of the sides, apply BF-6 glue slightly (literally in micro portions) along the film overlap line. You can press right away. In this case, it is better to start gluing from the middle. This method is more laborious in comparison with the more laborious, but in terms of the strength of the seam, the result is much better.

In addition, the adhesive layer is protected on both sides from the active effect of the working coating (spraying) of the membrane. To eliminate irregularities, the film obtained in this way must also be ironed again. In this case, the glue seam should be isolated from the paper with a lavsan film (from a roll), otherwise the heated glue, if it is outside the seam, will stick to the paper sheet. After heat treatment, micro-folds may appear on the film as a result of eliminating irregularities. The main thing is that the resulting film should be completely flat without bulges and warpage. One should not hope that in the future, when stretching it on the insulator, such defects will be corrected.

The thickness of the glue seam after smoothing with a heated iron is about 20 microns, and its effect on the total weight of the film is minimal, and the strength of such gluing is quite sufficient.

After trimming, a workpiece with dimensions of 70x120 mm is obtained with a glue seam running along the axis of symmetry (Fig. 2). It should be added that it is better to stock up on such semi-finished products for future use in order not to repeat the whole process again in case of failure.

Despite the fact that the film removed from the capacitor is initially metallized, the issue of covering the membrane is not decided in favor of its native conductive coating. And there are two reasons for this. First, one-sided, as in this case, metallization leads to twisting of the film, which is practically impossible to eliminate, which is very inconvenient in operation and ultimately leads to warping of the membrane.

Secondly, an extremely thin metallization layer is prone at breaks, in particular, at the output lobe, to a complete loss of conductivity, which, in turn, leads to a loss of efficiency of the entire emitter as a whole. Therefore, the removal of metallization, as described in, does not contradict the general idea in this case.

So, the semi-finished product in the form of a smooth, without signs of warping, transparent film with the indicated dimensions is ready, and now you can proceed to the next stage - the stage of membrane spraying. Judging by the debates on thematic forums, the technologies for manufacturing branded membranes remain secret, and, perhaps, they are not realizable at the amateur radio level, nevertheless there are a lot of ideas. One of the most affordable proposed methods for coating a substrate is the spraying of Lana antistatic agent or other aerosols with similar physical properties.

Such a coating is classified as high-resistance, and its specific resistance is 2 ... 5 GΩ / cm². And despite the fact that such coverage is presented as a trial, temporary, in fact, the final result in relation to GT can be quite acceptable. So, almost all prototypes, subject to the manufacturing technology, worked without serious claims to such spraying. However, it was not possible to estimate the lifetime of such a deposition.

Some samples successfully worked for more than a year without a decrease in sensitivity, after which, one way or another, they were modernized. It should also be noted that such membranes are unpretentious for storage in frost (-30 ° C) or at elevated temperatures (+50 ° C). Satisfactory tolerance and 100% humidity (with subsequent drying). Over time, the resistivity of such a coating tends to increase, which can lead to a noticeable increase in the time of accumulation of charges on the membrane from the moment the polarizer is switched on.

The spraying process is quite simple. To begin with, you need to make a protective frame from thin even cardboard. The frame is needed so that the spray from the sprayer falls only on the working area of ​​the film. In fig. 2 this area is highlighted in gray. It is better to reduce the inner dimensions of the frame by 0.5 ... 1 mm to limit the transitional area of ​​the spraying. The marked cuts on the membrane petal are made immediately before stretching it on the insulator or in the process of stretching, in place. We apply the frame to the film and spray it from a distance of 20 ... 25 cm.

This should be done in moderation, so that there are no sagging on the film. Antistatic agent is active against BF-6 glue, but the latter is already protected by layers of films. The operation must be repeated twice with an interval of 2 hours. The opposite side of the membrane should be sprayed in the same way. It is recommended to cover the petal with an additional layer or even two, since problems associated with a decrease in sensitivity due to

Convenient to use are self-tapping screws with flat heads of the specified diameter, clamped along the thread by the "crocodiles" of the voltmeter. Of course, these voltage values ​​are approximate and depend on the properties of the antistatic agent, which may differ from manufacturer to manufacturer. In this case, we are talking about the products of the Novomoskovsk plant. If necessary, the number of spray layers can be increased. The principle is simple - the thinner the layers, the more there are.

But such antistatic agent as "Lyra" is less preferable. A coating based on it has a noticeably higher resistivity and, in the end, may be comparable to the leakage resistance of the entire structure, which will complicate the task. For example, in the previous measurement circuit, the voltmeter reading may be in the range of millivolts. In addition, "Lyra" has a higher stickiness, which creates certain problems.

Fixed electrodes

From one-sided foil fiberglass with a thickness of 1.5 mm, we cut out two identical blanks according to the dimensions of the finished electrode, as in Fig. 4. Both NEs - inner and outer - are the same, except that on the outer (farthest from the ear) electrode, instead of fixing holes with a diameter of 2 mm, as shown in fig. 4, threaded holes M2 are made.

You do not need to drill the mounting holes yet. But you can drill holes for perforation when using a stationary drilling machine at the same time. To do this, both parts must be pressed together with foil-coated sides and a stencil must be applied to them. The package obtained in this way is fastened with miniature clamps. Holes should be drilled within the boundaries of the foil area, with the exception of the lead-out tab.
At the end of the drilling, the package is disconnected, the burrs on the drilled electrodes are removed with a small file and sandpaper. You may then have to drill through all the holes to clean the holes. Ultimately, the working surfaces of the NE should be, as they say, in perfect condition. If the use of a manual electric drill is supposed, then in order to avoid possible distortions of the holes of the NE, it is better to drill separately, one by one.

The next stage is the manufacture of insulators. To do this, you will need a one-sided foil glass fiber laminate (use of getinax is allowed) with a thickness along the width of the selected gap. Let it be a compromise option from the previously indicated values, for example 0.8 mm, from the standard range of SF-1 fiberglass. Of course, the gap and thickness of the NE can be chosen differently, based on the available materials or for other reasons.

This will mainly lead only to a change in the thickness of the emitter, which is easy to take into account in the future. In this case, the sensitivity is corrected by the selection of the polarization voltage. One emitter will need two parts - A and B, as in Fig. 5. Insulator B is shown only fragmentarily (lower part), and for its manufacture it is possible to use non-foil fiberglass, otherwise the details are identical.

You can cut the insulators with a conventional cutter, having previously drilled holes in the corners with a thin drill. After that, the foil should be removed, except for the area highlighted in color (Fig. 5) - this is the contact area for gluing the membrane petal and soldering the cable conductor.
The cutout in the lower part of the insulator B is designed so that the adhesive contact between the membrane petal and the contact pad does not deform during assembly of the package. In the absence of foil-clad fiberglass of the specified thickness, the contact petal can be cut out of copper foil and glued in place with the Moment universal glue.

Then, with epoxy glue (plasticizer is required), the insulators are glued to the inner (foil) sides of the stators, and the tab of the insulator A must be directed in the same direction as the foil side of its stator. In order to save material, insulators can be composed of individual strips 5 mm wide. In this case, it is better to use a mandrel in the form of a thin rectangular plastic plate with dimensions of 50 × 85 mm, which guarantees good repeatability of the internal dimensions of the insulator frames. After drying, any beads of epoxy adhesive on the working surfaces of the stators must be removed.

Now you can drill the mounting holes and it is better to do this simultaneously on both NEs, precisely aligning them with insulators to each other and fixing them with clamps. First, through holes with a diameter of 1.5 mm should be drilled. Then disconnect the NE and drill holes up to 2 mm on the inner (closest to the ear) electrode, and cut the M2 thread with the first tap number on the outer electrode. Ultimately, the bag will be secured with 5 mm M2 countersunk screws. Therefore, on the outside of the inner electrode, it is necessary to countersink the holes for the screw heads. The thread in fiberglass has limitations in reliability, and this must be borne in mind when assembling the package.

At the end of all work related to machining, the parts should be thoroughly cleaned of dust and degreased. Before painting the conductive surfaces of the NE insulators, it is necessary to protect them with adhesive tape from paint falling on them. After painting, you should pay attention to the quality of the coating. Hard blotches protruding above the surface, which sometimes do occur, should be cleaned out.

Assembling the emitters

At this stage, first of all, it is necessary to perform the correct stretching of the membrane, which is attached to the NE with insulator A. This is an important point on which the success of the work in general depends. Stretching the membrane itself is not that difficult and time consuming. It is much more difficult to work on adjusting its tension, when you have to partially peel off the membrane. In this case, tears of the film are possible. Therefore, it is desirable that the desired result is obtained the first time. You can pre-practice on a dummy - uncoated film, which is not a pity. The acquisition of a certain skill is crucial. In extreme cases, you can use a film with a thickness of 10 microns. Such a film is used in capacitors K73-16 for a rated voltage of 400 V.

The prepared membrane is carefully placed on the stator so that its sprayed part is exactly above the perforation of the electrode, and its petal coincides with the foil section of the insulator. In fig. 6 numbers indicate the sequence of actions.

First, at point 1 on the end side of the stator, a smear of the Moment universal glue should be applied and after 10 ... 20 s, bend and fix the upper edge of the membrane on it. Further, at points 5 and 8, you also need to apply light dotted strokes of glue on the end. After holding, the lower part of the membrane is fixed with moderate tension in the direction of the arrows. You do not need to be especially zealous with glue.

The film is lightweight and holds well even with minimal use. After holding for about 10 minutes, you should lightly coat the end areas 1 -2 and 1-11 with a thin layer of glue (hereinafter, they are indicated by bold lines). Again exposure for 10 ... 20 s - and the upper edge of the membrane is bent over the NE end with simultaneous tension along the arrows. The same operation is performed with the lower part of the membrane (sections 5-6 and 7-8).

This completes the vertical stretch. In this case, the middle part of the membrane should turn out to be flat, longitudinal (vertical) waves can only be at its edges. After a longer exposure of up to 30 minutes, you can stretch in width. For this, a thin layer of glue is applied to section 3-4 of the stator end face along its entire length. Exposure 10 ... 20 s - and also carry out the bend of the lateral edge of the membrane to the end along the entire length with a tension slightly greater than it is necessary to eliminate waves.

And again exposure for 10 minutes, after which the opposite edge of the membrane is glued to the other end of the electrode in the same way (section 9-10). The result of the work performed should be a completely flat membrane without waves or folds. You can slightly blow on the membrane, making sure that there are no oscillations of its individual sections. The better the membrane is made, the fewer problems with stretching it.

The Moment glue holds the membrane tension well, while allowing to correct a possible defect. This will require acetone, but it should be used in minimal portions so that it does not leak onto the sprayed part of the membrane, otherwise leaks may appear, which can often be eliminated only by replacing the membrane itself. But if the defect is noticed even at the time of gluing, when the glue has not yet completely grabbed it, then it is possible to quickly separate the section of the film from the insulator without resorting to acetone. A NE with a membrane stretched on it is shown in Fig. 7.

Now you can roughly assess the quality of the membrane tension by listening to its resonant response when you tap the electrode with your finger. A "flabby" sound indicates that the tension is too weak, while ringing, on the contrary, indicates that the tension is too high. The sound should be low in tone and elastic. Generally speaking, it is better to slightly overtighten the membrane than understretch.

Ultimately, slightly higher losses at frequencies below 40 ... 50 Hz are not as important as the consequences of a too loosely stretched membrane. These include a rather unpleasant phenomenon that arises with a small gap or due to an excessively weak tension of the membrane - this is its relaxation oscillations, and sometimes adhesion to one of the NEs. The reason for this phenomenon is that in the event of an asymmetry in the position of the membrane in the gap, a difference force acts on it, tending to pull the membrane to the NE closest to it at the moment.

But as follows from the conversations on the Internet forums, even branded products are not immune from this. Then, at the point of contact of the membrane petal with the foil-coated section of the insulator, a little conductive glue should be applied so as to ensure contact with the foil of both sides of the membrane petal, cutting off its excess, as shown in Fig. 8 (fragment of NE).

Such a contact, despite its seeming doubtfulness given the oily properties of "Lana", is actually quite reliable. The remaining free corner of the output of the insulator is intended for soldering a conductor with a polarizing voltage + Uо. Conductive glue-paste can be prepared on your own by thickly mixing fine copper sawdust filed with a file in a drop of PF-283 varnish. Such a paste hardens quickly, and it should be prepared immediately before use.

The smartphone, which Apple will release next year, is rumored to have a standard 3.5mm audio output. This means that music on this device can only be listened to through wireless headphones or headphones with a Lightning connector (probably compatible plugs will be included in the kit). But what to do for those who have already picked up headphones of the ideal design with decent sound - do not give them up because of a new whim of Apple? Fortunately, you can build a wireless adapter for any headphones with your own hands, especially since almost no skills are required for this, and it will cost very cheaply.

How to make wireless headphones with your own hands?

In addition to the actual headphones, you will need two more components: a Bluetooth sound adapter and a portable charger to power it.

A Bluetooth adapter usually looks like a USB flash drive with a 3.5mm audio jack. It costs less than two hundred rubles on AliExpress.

Portable chargers come in different sizes, but for these purposes the smallest one - the size of a lighter is best suited. For example, something like this:

It is powered by two batteries or AA rechargeable batteries. When they sit down, they can simply be replaced with new ones or charged ones.

You can find a miniature Power Bank with a built-in battery, like this:

Once you have all of these components, you can start building your wireless headphones.

1. Insert the Bluetooth adapter into a charged wireless charger or one with fresh batteries. If all is well, the blue LED in the adapter will flash.

2. Connect the headphone plug to the audio input of the Bluetooth adapter.

3. Open Bluetooth settings on your smartphone and search for Bluetooth devices. There should be a sound adapter among them, connect to it. If he asks for a code, enter "0000".

4. Turn on music and enjoy your favorite songs.

Of course, your headphones will be considered wireless only conditionally - they will have wires, but you no longer need to connect them to the audio output of your smartphone. The same wireless headphones can be built if the 3.5 mm plug has stopped functioning normally in your smartphone, and for some reason you do not want to repair it. Keep in mind that Bluetooth has an extremely limited range, and if you move more than ten meters away from your smartphone, the sound in the headphones will become intermittent or completely disappear.

Some lovers of listening to music in the evening occasionally encounter breakage of their headphones. It is extremely annoying to constantly acquire new headphones... The most primitive way out of this situation is to stop listening to your favorite songs in the evening or not fall asleep, but it is not so primitive to give up sleep or pleasure, the one that a music lover gets. A particularly advantageous solution would be to assemble the headphones from the remaining ones.

You will need

• Non-working headphones, soldering iron, scissors, electrical tape.

Instructions

1. As usual, only one of a pair of headphones breaks continuously, respectively, the other will invariably be whole. There is no point in throwing out one of your work headphones. With a little effort, it is allowed to collect personal headphones... If your headphones do not work only because of the bent cable, it is allowed to replace the rod plug with a new one or try to finish the existing one.

2. Use thin scissors or a sharp knife to remove the plastic part from the plug. Strip the wires, remember their position when cleaning the plug from plastic. After cleaning the plug, try soldering the wires to the plug connectors. Remember, the signal is transmitted more than each one through the wires that have been soldered, and the twisted wires lose some of the signal during transmission. Note that when connecting two wires, you must make sure they are the same color.

3. If a breakdown appears in the earpiece itself, it is allowed to replace it with another one, say, from another broken pair. If the wires are unsoldered from the speaker itself, they can also be easily soldered. It is worth noting that you should not confuse the left and right speakers when replacing them. If the soldering iron has too thick a tip, it is allowed to purchase a similar one and easily grind it off. The smaller the tip diameter, the lower the output power of the soldering iron.

4. Later, after the headphones have been fully restored, you just have to test them on any music device.

The headset is most often used with a mobile phone or player. Sometimes it is different in cost and quality: from inexpensive to heaped up and stuffed with the latest developments in the field of electronics. Here the choice falls entirely on your shoulders and head. But it is allowed to do it easier, and not even toil with a choice in the store. Collect your headset... This is not at all as difficult as it might seem at first glance.

You will need

• - adapter;
• - the wire;
• - insulating tape;
• - soldering iron;
• - microphone;
• - speaker.

Instructions

1. Take a shabby one for confidence headset... It is not even necessary that it fit the standard connector on your phone. For this purpose, an adapter will serve, one that you need to buy or dig up in your treasury. It is needed so that later you can connect any headphones more closely. It is allowed to use an adapter, the one that often comes with a particular player.

2. Take the adapter and cut off the part that should fit into the player. The wires that appear (there should be three of them) you need to strip, that is, cut off the top film with a knife or scissors. After that, take care of the headset itself.

3. Disassemble the place where the headset has a microphone, sound button and / or call button. Cut the wire that goes to the earphone so that the ends of the wires are visible. That is, do not cut at the root.

4. Next comes the process of adhesion. Connect the wires based on color. They must be the same. Solder scarlet with red, white with white, etc. After connecting the wires, wrap them with electrical tape. This is necessary both for the strength of the structure and for your safety.

5. Place the soldered wires back into the microphone box. Plug in all sorts of headphones and you're done. Enjoy the quality of the sound and the knowledge that you have assembled this little miracle of technology with your own hands.

6. Recommendations for setting up a wireless headset and phone: The secret is primitive. All devices (both phone and headset) must be turned on. On your phone, start searching for devices in the bluetooth menu. Press the headset power button at the same time until the indicator comes on. Make sure it is on and not blinking. The phone should detect headset and connect with her. If this does not happen immediately, easily repeat the search for devices with a tighter headset turned on.

Note!
This headset is no different from the purchased one in terms of its collations, so you can adjust the volume and equalizer as you like without horror.

Helpful advice
The possibilities of using a headset are not limited to its wired types. Users are gradually switching to wireless communication. The truth here, as they say, is not for everybody!

Ready headphones, even solid ones, fail relatively quickly. In the hands of a home master, they traditionally begin to work again, but it is much more comfortable to have head headphones that won't break. You can make them yourself.

Instructions

1. Purchase a plug that matches the type of headphone jack on the unit. Particularly common are the 6.3 mm (1/4 ") and 3.5 mm (1/8") diameters of the 3-pin stereo jacks. The former are used mainly in stationary equipment, the latter are used in portable equipment, but there are exceptions.

2. Remove the cover from the plug. Pass a flexible but durable four-core cable through the hole. A fairly frequent oversight of novice craftsmen is further: they solder the conductors to the contacts of the plug, forgetting to pass the cable through the cover in advance.

3. Locate the cable support on the plug. It has a hole in it. Solder two of the four cable conductors to this hole. Solder two more conductors, respectively, to one small contact and to the other, putting small insulating tubes (cambric) on them in advance. After soldering, close the contacts with these tubes.

4. Wrap the cable with two layers of electrical tape, and then fix its wrapped section in the rack.

5. Close the plug. Use an ohmmeter to check that there are no short circuits.

6. Place two identical small speakers with an impedance of 8 ohms in round resonator casings, for which it is allowed to use perfectly cleaned plastic jars from shoe polish. Step by step with each of them, turn on a resistor with a nominal value of about 30 ohms. They also have to be identical.

7. Bend the headband from a metal ruler. Mount the emitters on it using any method that is comfortable for you. These can be, say, screws and nuts. Headphones are not required to have sharp protrusions that could scratch your ears.

8. Connect two wires to each emitter (consisting of a speaker and a resistor), one of which in both cases must be combined with a stubborn plug, and the second with one of its small contacts.

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This element is quite primitive in execution, but at the same time it is very significant, because it is the basis for other, more difficult elements. Regardless of what build you are, you will be able to make an exit on one hand.

Instructions

1. Pull-ups and push-ups. In order for you to easily perform this element, learn to pull yourself up on the horizontal bar 10 times, without pulling your legs, but keeping them straight, and push up from the floor at least 20 times.

2. Checkbox. The next step is to fix the checkbox as shown in the picture. In order to make it easier to make this part of the element, after pulling up it is allowed to put the forearm parallel to the crossbar, and later go to the flag.

3. Push up on the horizontal bar. Later, after you go out into the box, you need to fix the second hand above the horizontal bar, as shown in the picture. To make it easier for you to do this, you can swing a little. From this location, you need to squeeze out of the horizontal bar and get out on even hands.

Note!
Be neat when you fix the flag, because if your hand comes off, it is permissible to injure your big finger.

Helpful advice
It may not work right away, but the main thing is persistence and regularity. If you develop these two factors, you can achieve tremendous results.

Headphones were invented in the 19th century. They have been greatly improved since then, and various form factors have emerged as well. Nevertheless, the thesis of their work remained the same.

Instructions

1. Headphones are based on emitters. The most famous emitter circuit is dynamic, with a moving coil. The continuous magnet is permanently attached to the earphone housing and creates a static magnetic field. Magnets can be ferrite (in more inexpensive models) and neodymium. In this magnetic field, a coil of wire is located, through which an alternating current modulated by a sound signal passes. When the current in a conductor changes, the surrounding magnetic field also changes.

2. A thin membrane is fixed on a flexible suspension, and a coil is attached to it. The latter moves due to the interaction of the continuous field from the magnet and the alternating field from the coil. The membrane begins to vibrate due to the movement of the coil. This vibration is transmitted through the air, and the ear perceives it as sound. The sound largely depends on what material the membrane is made of. It can be a synthetic polymer film in cheaper models; cellulose, mylar and other materials in mid-range headphones and titanium in more expensive devices.

3. This scheme is used in about all modern headphones of various form factors. Dynamic emitters also have a number of disadvantages. So, due to the relatively low speed of reaction to the metamorphosis of sound, the membrane is often not able to perfectly reproduce low and high frequencies in an identical manner. This snag is extremely demanded for "liners" and "inserts". Consequently, there were models of dynamic headphones with two emitters. Another snag is the unevenness of the magnetic field where the coil moves. This makes the sound somewhat unexpected and unstable. For this reason, some other emitter schemes were invented, with their own advantages and disadvantages.

Modern young people use headphones not only for their intended purpose. For many, they have long become a favorite accessory and an integral part of the image. In this master class, we propose to refine them by getting rid of the cheap plastic case. We will make a wooden headphone case with our own hands. Such a product looks stylish, original and by no means cheap.

Materials (edit)

For work, prepare:

• the headphones themselves;
• block of wood;
• small screws, 4 pcs .;
• linseed oil for finishing and polishing;
• screwdriver;
• lathe;
• sandpaper;
• cotton fabric;
• Dremel.

Step 1... Disassemble the plastic case of the original earbuds. They often use plastic clips as fasteners. They can be opened easily with an ordinary screwdriver.

Step 2... Take the prepared block of wood. At this point, rough it up and cut it to fit.

Step 3... On a lathe, on the inside of the workpiece, cut a groove for the speakers and related filling. During work, be sure to try on parts to each other.

Step 4... When the fit is as accurate as possible, grab sandpaper and gently sand the surface of the workpieces.

At the same stage, you can give the final shape to the body from the outside. Grind the surface thoroughly at the end of the work.

Step 5... Mark the workpieces and make holes and grooves for wires, screws and other protruding elements.

Step 6... Apply oil to the resulting earphone housing. Give it a little time to absorb and then polish the items.

First, take a piece of press board or hard cardboard 130X130 mm in size. A hole is cut out in it and the head is glued into it (Fig. 1).

Fig. 1 ... Dynamic head panel:
1 - cardboard, 2 - head, 3 - terminals

Then in the sponge-ear cushion cut out (or pluck out) a recess for the speaker housing (Fig. 3), and in the sponge-cushion (Fig. 2) make an oval-shaped hole. Its inner edge is cut from the side adjacent to the ear.

Fig. 2.Sponge pillow.

Rice. 3. Sponge-ear cushions with a recessed head under the body.

The lead wires are soldered and, if necessary, an additional resistor, the resistance of which is selected experimentally, depending on the power of the amplifier. Several holes are punched in the cardboard panel and wires are passed through them.
The surfaces of the sponges and panels are covered with adhesive and allowed to dry. After that, glue is applied again and all three parts are connected together, having previously passed the wires outside. The finished earphone must be placed under the press for several hours until the glue dries. To avoid short circuits that can damage the ULF, pass the wires through the sponge using an invisible hair clip.

The second telephone is made in the same way.

The headband is a piece of rubber tape about 5 cm wide (it is also sold at the pharmacy).
A decorative pad is glued to the outer side of the ear cushion, under which a headband tape will be laid (Fig. 4).

Rice. 4. DIY headphones:
1 - rubber band, 2 - leads.

Now it remains to solder a three-wire connecting wire with a connector to the heads' terminals, and the stereo phones are ready to work.
You can connect the phones with a steel tape or use a ready-made case from old worn-out headphones.

Fig. 5. The appearance of ready-made headphones made by hand(phones are upholstered in velvet).