Hi all! Here is an article about making an unusual table radio their hands.

It's cool when appearance an object hides its functionality. In order to use this radio, you will have to turn on “Sherlock Holmes” or “Miss Marpool” :) First of all, those around you see a simple wooden sculpture that does not give any hints about what it is or how it can be used. Everything needs to be found out experimentally.

To turn on/off, adjust the range and change the volume, the radio has two rotating rings lying on top of each other. The round base is a speaker that you need to turn to turn it on. homemade.

Due to the spherical shape and weight distribution, craft sits stably on the table (vanka-stand principle). With the exception of the electronic parts, the ball radio is made entirely of wood. The body is made of layers of wood different breeds(layers have different thicknesses).

Step 1: Construction

After a lot of research, a dozen different sketches and brainstorming, I finally found the “ideal design”. Adjustment will be made using rings rather than potentiometer wheels.

Step 2: Selecting wood

During the manufacture of the case crafts Was used different kinds wood We print out the templates, glue them onto the wood and begin sawing and cutting out the wooden blanks.

Step 3: Assembling the “ball”

Let's sand the cut pieces.

Step 4: Turning the body

Let's install the workpiece in lathe and let's start sanding. However, be very careful. Why? After a second, I was "stunned" by the workpiece being torn into small pieces, but I was lucky and was able to find each piece so that I could glue the body back together. The cause of the rupture is an unstabilized workpiece.

Step 5: Add Electronics

Especially for crafts I purchased a simple radio set that included two potentiometers (one for adjusting the volume and turning the radio on/off, the second for selecting the band).

The interior has mounts for electronics. Potentiometer shafts are installed in these mounts. Upper for sound, lower for changing range.

When everything is prepared, sanded and soldered, you can connect the parts together.

I tried to make this homemade VHF receiver in a “retro” style. Front End from car radio. KSE marking. Next, the IF unit on the KIA 6040, the ULF on the tda2006, the 3GD-40 speaker, in front of which there is a 4-5 kHz notch, I don’t know exactly, I selected it by ear.

Radio receiver circuit

I don’t know how to do digital tuning, so it will just be a variable resistor; for this VHF unit, 4.6 volts is enough to completely cover 87-108 MHz. Initially I wanted to insert an ULF on P213 transistors, since I had assembled and rebuilt the “retro” one, but it turned out to be too bulky, so I decided not to show off.

Well network filter installed, of course it won't hurt.

There was no suitable dial indicator, or rather there was one, but it was a pity to install it - there were only 2 left, so I decided to remake one of the unnecessary M476s (as in Ocean-209) - I straightened the needle and made a scale.

Backlight - LED Strip Light. The vernier is assembled from parts of various radios, from tube radios to China. The entire scale with the mechanism is removed, its body is glued together from many wooden parts, rigidity is given by the textolite on which the scale is glued and all this is pulled to the body of the receiver, simultaneously additionally pressing the front panels (those with a mesh), which are also removable if desired.

Scale under glass. The tuning knobs are from some radio from a junkyard, tinted.

Overall, a flight of fancy. I have long wanted to try out the curvature of my hands by building something similar. And here there was absolutely nothing to do, and scraps of plywood from the renovation remained, and the mesh turned up.

Construction of the building

To make the body, several boards were cut from a sheet of treated fiberboard 3mm thick with the following dimensions:
— front panel measuring 210mm by 160mm;
- two side walls measuring 154mm by 130mm;
— upper and lower walls measuring 210mm by 130mm;

— rear wall measuring 214mm by 154mm;
— boards for attaching the receiver scale measuring 200mm by 150mm and 200mm by 100mm.

The box is glued together using wooden blocks using PVA glue. After the glue has completely dried, the edges and corners of the box are sanded to a semicircular state. Irregularities and flaws are puttied. The walls of the box are sanded and the edges and corners are sanded again. If necessary, we putty again and sand the box until flat surface. We cut out the scale window marked on the front panel with a finishing jigsaw file. Using an electric drill, holes were drilled for the volume control, tuning knob and range switching. We also grind the edges of the resulting hole. Cover the finished box with soil ( automotive soil in aerosol packaging) in several layers with complete drying and leveling out unevenness emery cloth. We also paint the receiver box with automotive enamel. We cut out the scale window glass from thin plexiglass and carefully glue it to the inside of the front panel. Finally, we try on the back wall and install the necessary connectors on it. We attach plastic legs to the bottom using double tape. Operating experience has shown that for reliability, the legs must either be firmly glued or fastened with screws to the bottom.

Holes for handles

Chassis manufacturing

The photographs show the third chassis option. The plate for fastening the scale is modified to be placed in the internal volume of the box. After completion, the necessary holes for the controls are marked and made on the board. The chassis is assembled using four wooden blocks with a cross-section of 25 mm by 10 mm. The bars secure the back wall of the box and the scale mounting panel. Posting nails and glue are used for fastening. Glued to the bottom bars and walls of the chassis horizontal panel chassis with pre-made cutouts to accommodate a variable capacitor, volume control and holes for installing an output transformer.

Electrical circuit of the radio receiver

prototyping did not work for me. During the debugging process, I abandoned the reflex circuit. With one HF transistor and a ULF circuit repeated as in the original, the receiver started working 10 km from the transmitting center. Experiments with powering the receiver with a low voltage, like an earth battery (0.5 Volts), showed that the amplifiers were insufficiently powerful for loudspeaker reception. It was decided to increase the voltage to 0.8-2.0 Volts. The result was positive. This receiver circuit was soldered and, in a two-band version, installed at a dacha 150 km from the transmitting center. With a connected external stationary antenna 12 meters long, the receiver installed on the veranda completely sounded the room. But when the air temperature dropped with the onset of autumn and frost, the receiver went into self-excitation mode, which forced the device to be adjusted depending on the air temperature in the room. I had to study the theory and make changes to the scheme. Now the receiver worked stably down to a temperature of -15C. The price for stable operation is a reduction in efficiency by almost half, due to an increase in the quiescent currents of transistors. Due to the lack of constant broadcasting, I abandoned the DV band. This single-band version of the circuit is shown in the photograph.

Radio installation

Homemade printed circuit board receiver is made according to the original circuit and has already been modified in field conditions to prevent self-excitation. The board is installed on the chassis using hot melt adhesive. To shield the L3 inductor, an aluminum shield connected to a common wire is used. The magnetic antenna in the first versions of the chassis was installed in the upper part of the receiver. But periodically metal objects were placed on the receiver and Cell Phones, which disrupted the operation of the device, so I placed the magnetic antenna in the basement of the chassis, simply gluing it to the panel. The KPI with an air dielectric is installed using screws on the scale panel, and the volume control is also fixed there. The output transformer is used ready-made from a tube tape recorder; I assume that any transformer from a Chinese power supply will be suitable for replacement. There is no power switch on the receiver. Volume control is required. At night and with “fresh batteries,” the receiver begins to sound loud, but due to the primitive design of the ULF, distortion begins during playback, which is eliminated by lowering the volume. The receiver scale was made spontaneously. The appearance of the scale was compiled using the VISIO program, followed by converting the image into a negative form. The finished scale was printed on thick paper laser printer. The scale must be printed on thick paper when there is a difference in temperature and humidity office paper will go in waves and will not restore its previous appearance. The scale is completely glued to the panel. Copper winding wire is used as an arrow. In my version, this is a beautiful winding wire from a burnt-out Chinese transformer. The arrow is fixed on the axis with glue. The tuning knobs are made from soda caps. The handle of the required diameter is simply glued to the lid using hot glue.

Board with elements

Receiver assembly

Radio power supply

As mentioned above, the “earthen” power option did not work. As alternative sources It was decided to use dead “A” and “AA” format batteries. The household constantly accumulates dead batteries from flashlights and various gadgets. Dead batteries with a voltage below one volt became power sources. The first version of the receiver worked for 8 months on one “A” format battery from September to May. A container is specially glued to the back wall for power supply from AA batteries. Low current consumption requires the receiver to be powered from solar panels garden lanterns, but for now this issue is irrelevant due to the abundance of “AA” format power supplies. The organization of power supply with waste batteries led to the name “Recycler-1”.

Loudspeaker of a homemade radio receiver

I do not advocate using the loudspeaker shown in the photograph. But it is this box from the distant 70s that gives maximum volume from weak signals. Of course, other speakers will do, but the rule here is that the bigger the better.

Bottom line

I would like to say that the assembled receiver, having low sensitivity, is not affected by radio interference from TVs and switching power supplies, and the quality of sound reproduction differs from industrial AM receivers cleanliness and saturation. During any power failures, the receiver remains the only source for listening to programs. Of course, the receiver circuit is primitive, there are circuits of better devices with economical power supply, but this homemade receiver works and copes with its “responsibilities”. Spent batteries are properly burned out. The receiver scale is made with humor and gags - for some reason no one notices this!

Final video

Finally, the long-awaited moment comes when the created device begins to “breathe”, and the question arises: how to close its “insides” and give the design completeness so that it can be used comfortably. This question is worth specifying and deciding what the case is intended for.

If it is enough for the device to have a beautiful appearance and “fit” into the interior, you can make the case from fiberboard sheets, plywood, plastic, fiberglass. The body parts are connected with screws or glue (using additional “reinforcement”, i.e. slats, corners, gussets, etc.). To give it a “marketable appearance,” the body can be painted or covered with self-adhesive film.

A simple and convenient way to make small cases at home is from sheets of foil fiberglass. First, all components and boards are laid out inside the volume and the dimensions of the case are estimated. Sketches of walls, partitions, board fastening parts, etc. are drawn. Based on the finished sketches, the dimensions are transferred to foil fiberglass, and blanks are cut out. You can make all the holes for the regulators and indicators in advance, since it is much more convenient to work with the plates than with a ready-made box.
The cut parts are adjusted, then, having secured the workpieces at right angles to each other, the joints on the inside are soldered with ordinary solder with a fairly powerful soldering iron. There are only two “subtleties” in this process: do not forget to give allowances for the thickness of the material on the required sides of the workpieces and take into account that the solder contracts in volume when it hardens, and the soldered plates must be firmly fixed while the solder cools so that they do not “sink.”
When the device requires protection from electric fields, the housing is made of conductive materials (aluminum and its alloys, copper, brass, etc.). It is advisable to use steel when shielding is required and magnetic field, and the mass of the device does not matter much. A case made of steel, sufficient to ensure mechanical strength of thickness (usually 0.3 ... 1.0 mm, depending on the size of the device), is especially preferable for transmitting and receiving equipment, since it shields the created device from electromagnetic radiation, interference, interference, etc. .
Thin sheet steel has sufficient mechanical strength, can be bent, stamped, and is quite cheap. True, ordinary steel also has a negative property: susceptibility to corrosion (rust). To prevent corrosion, various coatings are used: oxidation, galvanizing, nickel plating, primer (before painting). In order not to deteriorate the shielding properties of the housing, its priming and painting should be done after complete assembly (or the oxidized strips of panels in contact with each other should be left unpainted (with a detachable housing). Otherwise, when assembling the housing parts “paint on a chamfer", cracks will appear that break the closed shielding circuit To combat this, spring “combs” are used (spring strips of oxidized hard steel, welded or riveted to the panels), which, during assembly, ensure reliable contact of the panels with each other.

The metal case made of two U-shaped parts is deservedly popular.(Fig. 1), bent from plastic sheet metal or alloy.

The dimensions of the parts are chosen so that when they are installed one into the other, a closed case without cracks is obtained. To connect the halves to each other, screws are used, screwed into the threaded holes in the shelves of the base 1 and the corners 2 riveted to it (Fig. 2).

If the material thickness is small (less than half the thread diameter), it is recommended to first drill a hole for the thread with a drill whose diameter is equal to half the thread diameter. Then, by striking a round awl with a hammer, the hole is given a funnel-shaped shape, after which a thread is cut into it.

If the material is sufficiently plastic, you can do without corners 2, replacing them with bent “legs” on the base itself (Fig. 3).

An even more “advanced” version of the rack, shown in Fig. 4.
Such a rack 3 not only fastens the upper panel 1 with the lower 5, but also fixes the chassis 6 in the body, on which the elements of the device being manufactured are placed. Therefore, no additional fasteners are needed, and the panels are not “decorated” with numerous screws. The bottom panel is attached to the stand using screw 2 passing through leg 4.
Thickness required material depends on the size of the case. For a small case (volume up to approximately 5 cubic dm), a sheet with a thickness of 1.5...2 mm is used. A larger body requires, accordingly, a thicker sheet - up to 3...4 mm. This primarily applies to the base (bottom panel), since it bears the main force load.

Manufacturing begins with calculating the dimensions of the workpieces (Fig. 5).

The length of the workpiece is calculated by the formula:

Having determined the length of the first workpiece, it is cut out of the sheet and bent (for steel and brass, the bending radius R is equal to the thickness of the sheet, for aluminum alloys- 2 times more). After this, the resulting dimensions a and c are measured. Taking into account the existing size c, determine the width of the second workpiece (C-2S) and calculate its length using the same formula, substituting:
- instead of a - (a-S);
- instead of R1 - R2;
- instead of S - t.

This technology guarantees precise connection of parts.
After manufacturing both halves of the body, they are adjusted, marked and mounting holes are drilled. In the necessary places, holes and windows are cut for control knobs, connectors, indicators and other elements. The control assembly and final adjustment of the body are carried out.

Sometimes it is difficult to fit all the “stuffing” of the device into the U-shaped half. For example, on the front panel you need to install a large number of display and control organs. It is inconvenient to cut windows for them in a bent part. A combined option will help out here. The body half with the front panel is made from separate sheet blanks. To attach them, you can use special corners shown in Fig. 6.

This part conveniently fastens three walls at once in the corner of the case. The dimensions of the corners depend on the dimensions of the structural elements being fastened.

To make a corner, a strip of mild steel is taken and fold lines are marked on it. The central part of the workpiece is clamped in a vice. With light blows of a hammer, the strip is bent, then turned over so that the bent part lies on lateral surface vice, and the middle part was slightly clamped. In this position, the bend is corrected and the deformation of the strip is eliminated. Now the second side of the part is bent, and, after editing, a ready-made fastening unit is obtained. All that remains is to mark the location and drill the holes in which to cut the threads.

Equipment, especially lamp equipment, requires housing ventilation. It is not at all necessary to drill holes throughout the entire body; it is enough to do them in places where there are powerful lamps (in top cover case), on the rear wall above the chassis, several rows of holes in the central part of the bottom cover of the case and two or three rows of holes on the side walls (in the upper part). There should also be holes around each lamp in the chassis. Above powerful lamps with forced ventilation Windows are usually cut out and a metal mesh is fixed into them.

IN Lately, as a result of rapid obsolescence, cases from computer system units appeared in landfills. These cases can be used to create various amateur radio equipment, especially since the width of the case takes up very little space. But such a vertical layout is not always suitable. Then you can take the casing from the system unit, cut it to the required dimensions and “join” it with a “cut” from a second similar casing (or separate panels - Fig. 7, 8).

With careful manufacturing, the body turns out to be quite good and already painted.

Radio receiver housing, decorative and protective elements

The acoustic characteristics of a radio receiver are determined not only by the frequency characteristics of the low-frequency path and loudspeaker, but also largely depend on the volume and shape of the housing itself. The body of the radio receiver is one of the links in the acoustic path. No matter how good the electroacoustic parameters of the low-frequency amplifier and loudspeaker are, all their advantages will be reduced if the radio receiver housing is poorly designed. It should be borne in mind that the body of the broadcast receiver is at the same time decorative element designs. For this purpose, the front part of the case is covered with radio fabric or a decorative grille. Finally, to protect the radio listener from accidental damage when touching conductive parts, the chassis of the radio receiver in the housing is protected back wall, on which the power circuit is blocked. Consequently, decorative and protective structural elements, which are elements of the acoustic path, as well as methods of their mechanical fastening, can have a significant impact on the quality of reproduction of sound programs. Therefore, we will consider each element of the design of the broadcast receiver housing separately.

Radio receiver housing must satisfy the following basic requirements: its design must not limit the frequency range regulated by GOST 5651-64; manufacturing process and assemblies must meet the requirements of mechanized production; manufacturing costs should be low; External design is highly artistic.

To satisfy the first requirement, the housing must provide good reproduction of the low and high frequencies of the radio audio range. For this purpose, it is necessary to make preliminary calculations of the shape of the hull. The final determination of its dimensions and volume is verified by the results of tests in an acoustic chamber.

In acoustic calculations, a loudspeaker diffuser is considered as a piston oscillating in the air, creating areas of high and low atmospheric pressure during forward and reverse movement. Therefore, it is far from indifferent in which housing the loudspeaker is placed: with an open or closed back wall. In a housing with an open rear wall, the condensation and rarefaction of air arising from the movement of the rear and front surfaces of the diffuser, bending around the walls of the housing, overlap each other. In the case when the phase difference of these oscillations is equal to n, the sound pressure in the plane of the diffuser is reduced to zero.

Increasing the depth of the housing according to design requirements is quite acceptable. The housing dimensions of radio receivers that have several loudspeakers cannot be calculated using the above formulas. In practice, the dimensions of multi-loudspeaker enclosures are determined experimentally based on the results of acoustic tests.

Tabletop broadcast receiver housing designs with a closed back wall are usually not used. This is explained by the fact that it is very difficult and impractical to design radio receiver housings with a closed volume, since the heat exchange mode of radio components deteriorates. On the other hand, enclosures with a tightly sealed back wall cause the speaker's resonant frequency to increase and cause unevenness in the frequency response at higher frequencies. To reduce frequency response unevenness at high frequencies inner side The housing is upholstered with sound-absorbing material. Naturally, such a complication of design can only be allowed in high-class radios, in furniture with external speaker systems.

To fulfill the second requirement for enclosures, it is necessary to be guided by the following considerations: when choosing a material for the enclosure, it is advisable to take into account the standards recommended by GOST 5651-64 for sound pressure amplification paths, given in Table. 3.

Table 3

As can be seen from table. 3, depending on the class of the radio receiver, the frequency range standards of the entire amplification path for sound pressure also change. Therefore, it is not always advisable to choose high-quality materials with good acoustic properties for all classes of radio receivers. In some cases, this does not lead to an improvement in the acoustic characteristics of the receivers, but increases their cost, since the loudspeaker is selected in accordance with GOST standards, which determines the range of reproduced frequencies. For these reasons, there is no need to improve the acoustic characteristics of the housing when the sound source itself does not provide the possibility of their implementation. On the other hand, the low-frequency path, which has a narrower frequency range, makes it possible to reduce the cost of the design of the low-frequency amplifier.

According to statistics, the cost of a wooden case ranges from 30-50% of the total cost of the main components of the receiver. The relatively high cost of the housing requires the designer to pay careful attention to the choice of its design. What is acceptable when designing radios? upper class, is completely inapplicable for class IV receivers designed for a wide range of consumers. For example, in radio receivers of the highest and first classes, in some cases, the walls of the case to improve sound reproduction are made of separate pine boards laid between two thin sheets plywood. Front sides the cases are covered with valuable wood veneer, varnished and polished. At the same time for case manufacturing radios of classes III and IV use cheap plywood, abundant wood veneer, textured paper or plastics. Metal cases are currently not used due to

satisfactory acoustic qualities and the appearance of overtones that are unpleasant to the ear.

To analyze the design, it is advisable to use the so-called unit cost, i.e. the cost per unit volume or weight of the material. In each specific case, knowing the cost of the housing and the amount of material used, it is possible to determine the unit cost. Regardless of the volume of material spent on the manufacture of the housing for a certain technological process, it exterior finishing, the unit cost has a constant specific value. For example, when producing receiver housings at a specialized enterprise or in workshops, the specific cost is 0.11 kopecks. This unit cost value also takes into account overhead costs: the cost of the material, its processing, finishing, wages. It should be borne in mind that the value of the unit cost of the housing corresponds to very specific materials and technological processes. Value 0.11 kopecks. refers to cases made of plywood, covered with cheap veneer (oak, beech, etc.) and varnished without subsequent polishing. For cases carefully polished and covered with more valuable types of wood, the specific cost increases by approximately 60%. Thus, to determine the cost of a wooden radio case, it is necessary to multiply the specific cost by the volume of material used (plywood).

The process of gluing the body of a radio receiver with valuable wood and subsequent polishing is quite labor-intensive, as it contains many manual operations, requires large areas for its processing and tunnel ovens for drying the treated surfaces. To save veneer, which is in short supply for a number of enterprises, it is replaced with textured paper on which a fiber pattern is applied. tree species. However, pasting radio receiver cases with textured paper does not improve the situation, since to create a good presentation requires repeated varnishing (5-6 times) followed by drying
in tunnel kilns. In addition, an additional operation is introduced - painting the corners of the body where the sheets of textured paper meet. Cost of finished buildings in a similar way, is not reduced due to the high labor intensity of the work.

The choice of material thickness for the walls of the housing should be made taking into account technical requirements requirements for the acoustic system of a radio receiver. Unfortunately, in the technical literature there is no detailed information about the choice of material grade and its effect on the acoustic parameters of receivers. Therefore, when designing cases, one can only be guided by brief information, set out in the work. For example, in high-end radio receivers to reproduce low frequencies of 40-50 Hz with a sound pressure of 2.0-2.5 n!m2, the thickness of the walls made of plywood or wood boards must be at least 10-20 mm. For radio receivers of classes I and II, when reproducing low frequencies of 80-100 Hz and a sound pressure of about 0.8-1.5 n/m2, a plywood thickness of 8-10 mm is allowed. Housings for speaker systems radio receivers of classes III and IV, having a cut-off frequency of 150-200 Hz and sound pressure up to 0.6 n/m2, can have a wall thickness of 5-6 mm. Naturally, it is very difficult to make wooden cases with a wall thickness of 5-6 mm, since it is impossible to ensure sufficient structural strength. Housings with thin walls are usually made of plastic, however, even in this case, stiffening ribs must be provided to eliminate vibrations of the housing walls.

For economic reasons, manufacturing plastic radio housings is more profitable than wooden ones. Despite the technological and economic advantages of plastics for the manufacture of housings, their use is limited to broadcast receivers with large dimensions and high acoustic characteristics.

It is well known that wood has good acoustic properties, so radios

the higher classes tend to have wooden bodies. For these reasons, plastic housings are made only for class IV radios and very rarely for class III devices.

The radio receiver housing must have sufficient structural strength and withstand mechanical tests for impact strength, vibration resistance and durability during transportation. Application of methods, adopted in the furniture industry, i.e., the implementation of butt connections using tenon joints, is not justified by economic considerations, since the manufacturing process becomes more complicated, and consequently, the standard time for processing and assembly operations increases. Typically, the angular mates of the walls of the housings of broadcasting receivers are carried out more simple methods, which do not cause technological production difficulties. For example, the walls of the body are connected with bars or squares, glued into the corner joints, or with the help of wooden strips, inserted with glue into the slots of the parts to be joined. Wooden walls can be connected with metal angles, staples, strips, etc. And yet, despite the measures taken to simplify manufacturing processes wooden buildings, their cost remains relatively high.

The most labor intensive technological processes are wood veneer covering, varnishing and polishing of body surfaces. The process of polishing the assembled body is especially difficult in corner joints, since in these cases manual operations cannot be avoided. It is natural, therefore, that the efforts of designers and technologists should be aimed at creating such a hull design, the manufacture of parts of which and assembly processes could be mechanized as much as possible. The most rational in this regard is the prefabricated design of the body, when individual parts of a simple shape undergo final processing and finishing, and then

mechanically combined into a common structure.

Rice. 37. Design of a prefabricated body.

There are other designs of collapsible housings. One of the domestic radio factories has developed a design in which side walls contact metal panels using bolted connections. In this case, the radio receiver chassis is an independent unit, independent of the housing design.

Naturally, the examples given do not exhaust all the possibilities for developing design designs for split housings. One thing is obvious - such designs are the simplest and cheapest.