Radio Corps, Decorative and Protective Elements

The acoustic characteristics of the radio receiver are due not only to the frequency response of the low-frequency path and the loudspeaker, but largely depend on the volume and form of the hull itself. The chassis of the radio is one of the stones of the acoustic tract. No matter how good the electro-acoustic parameters of the low frequency amplifier and the loudspeaker, all their advantages will be reduced if the case of the radio is unsuccessfully designed. It should be borne in mind that the housing of the broadcast receiver at the same time is decorative element Designs. For this purpose, the front part of the hull is closed by radio or decorative lattice. Finally, to protect the radio listener from accidental damage when touched to conductive parts, the radio chassis in the housing is protected by the rear wall, on which the power chain lock is installed. Consequently, decorative and protective elements of the design, which are elements of the acoustic path, as well as methods for their mechanical fasteningmay have a significant impact on the quality of sound program playback. Therefore, we consider each element of the design of the housing of the broadcast receiver separately.

Corps of the radio must meet the following basic requirements: its design should not limit the frequency range, regulated by GOST 5651-64; The manufacturing and assembly process must comply with the requirements of mechanized production; The cost of manufacture should be low; External decoration - highly artistic.

To meet the first requirement, the case must provide good reproduction of low and high frequencies of the radio receiver. From this purpose, it is necessary to produce preliminary calculations of the shape of the body. The final definition of its size and volume is checked according to the test results in the acoustic chamber.

In acoustic calculations, the loudspeaker diffuser is considered as a piston fluid that creates with direct and reverse movement of an increased and reduced atmospheric pressure. Therefore, it is far from indifferent, in which case the loudspeaker is located: with an open or closed rear wall. In the housing with an open rear wall of thickening and air loss, arising from the movement of the rear and front surfaces of the diffuser, the ribbing of the housing walls are superimposed on each other. In the case when the phase difference of these oscillations is equal, the sound pressure in the diffuser plane is reduced to zero.

Increasing the depth of the case according to constructive requirements is quite acceptable. The sizes of the rates of radio receivers, which have several loudspeakers, cannot be calculated according to the above formulas. Practically sizes of cases with multiple loudspeakers are determined experimentally according to the results of acoustic tests.

The design of the housings of broadcast receivers in desktop design with a closed rear wall usually do not apply. It is explained by the fact that it is very difficult and inappropriate to design the hosges of radio colors with a closed volume, as the heat exchange mode of radio components deteriorates. On the other hand, the housings with a tightly closed rear wall cause an increase in the resonant frequency of the loudspeaker and the appearance of non-uniformity of the frequency response to more high frequencies. To reduce the non-uniformity of the frequency response at high frequencies, the inner side of the housing is surrounded by sound-absorbing material. Naturally, such a complication of the design is possible to admit only in the highest radio receivers, in the furniture design with remote acoustic systems.

To fulfill the second requirement for enclosures, it is necessary to be guided by the following considerations: when choosing a material for the case, it is advisable to consider the norms recommended by GOST 5651-64 on the amplification paths on the sound pressure shown in Table. 3.

Table 3.

			Classes standards
Parameters
			Higher
Frequency character		KV,			60-6 OOO	80-4000		100-4 LLC.
Pack of all tract		Sv,
Strengthening sound		Dv
Pressure		VHF			60-15 LLC.	80-12 000		200-10000
Parameters	Range			Classes standards
Frequency character	KV,			150-3500			200-3000
Pack of all tract	Sv,
Strengthening sound	Dv
Pressure	VHF			150-7000			400-6000

As can be seen from the table. 3, depending on the class of the radio, the rates of the frequency range of the entire amplification path on sound pressure are changed. Therefore, it is not always appropriate for all classes of radio receptions to choose high-quality materials with good acoustic properties. In some cases, this does not lead to an improvement in the acoustic characteristics of the receivers, and increases their cost, since the loudspeaker is selected in accordance with the norms of GOST, which determines the range of reproducible frequencies. For these reasons, it is not necessary to improve the acoustic characteristics of the case, when the sound source itself does not provide the possibility of their implementation. On the other hand, a low-frequency path having a narrower frequency range gives the availability of a low frequency amplifier design.

According to statistics, the cost of the wooden housing ranges from 30-50% of the total value of the main nodes of the receiver. The relatively high cost of the body requires a careful relationship to the selection of its design. What is permissible when designing top-class radio receivers, is completely non-applicable for receivers IV classes designed for a wide range of consumers. For example, in the radio receivers of the highest and first classes in a number of cases, the walls of the case to improve sound reproduction are made of separate pine boards, laid between two thin sheets of plywood. The facial sides of the body are covered with veneer of valuable wood, varnish are covered and polished. At the same time for manufacturing buildings Radio receivers III and IV classes are used cheap plywood, deficiencies, wood veneer, textured paper or plastics. Metal enclosures are currently not applied due to

satisfactory acoustic qualities and the emergence of unpleasant overtone hearing.

To analyze the design, it is advisable to use the so-called specific value, i.e., the value of the unit volume or weight of the material. In each case, knowing the cost of the body and the amount of material spent, one can determine the specific value. Regardless of the volume of material expended on the manufacture of the housing for a certain technological process of its exterior decorationThe specific value has a constant specific value. For example, in the manufacture of receiver enclosures on a specialized enterprise or in the workshops, the specific value is 0.11 kopecks. This value of the specific value takes into account the overhead: the value of the material, its processing, finishing, wages. It should be borne in mind that the value of the specific cost of the case matches quite defined materials and technological processes. Value 0.11 kopecks. Refers to housings made of plywood, sauked cheap veneer (oak, beech, etc.) and varnish coated without subsequent polishing. For enclosures, carefully polished and plated by more valuable wood, the specific value increases by approximately 60% - thus, to determine the cost of the wooden case of the radio receiver, it is necessary to multiply the value of the specific value to the amount of material spent (plywood).

The process of pasting the case of the radio receiver in valuable rocks of the tree and the subsequent polishing is quite time-consuming, as it contains many manual operations, requires large areas for its processing and tunnel furnaces for drying the treated surfaces. For the sake of veneer saving, which for a number of enterprises is deficit, it is replaced with textured paper on which the fiber pattern is applied wood breed. However, pasting of cases of radio receiver textured paper does not improve position, since it requires a multiple varnish coating (5-6 times) with a subsequent drying
In tunnel furnaces. In addition, an additional operation is introduced - the color of the corners of the housing, where the sheets of textured paper are joined. The cost of the hulls trimmed in a similar way is not reduced due to the large complexity of the work.

Choosing the thickness of the material for the walls of the case should be made with regard to technical requirementspresented to the acoustic system of the radio receiver. Unfortunately, in technical literature there are no detailed information on the choice of a variety of material and its influence on the acoustic parameters of the receivers. Therefore, when constructing buildings, you can only be guided brief informationoutlined in work. For example, in the highest-class radio receivers to play low frequencies of 40-50 Hz with sound pressure of 2.0-2.5 N! M2 The wall thickness made from plywood or joinery, should be at least 10-20 mm. For radio receiver I and II classes when reproducing low frequencies of 80-100 Hz and sound pressure of about 0.8-1.5 N / m2, plywood thickness is allowed 8-10 mm. Cases for acoustic systems Radio receivers III and IV classes having a boundary frequency of 150-200 Hz and sound pressure up to 0.6 n / m2 may have a wall thickness of 5-6 mm. Naturally, it is very difficult to perform wooden housings with a wall thickness of 5-6 mm, as it is impossible to ensure sufficient strength of the structure. The housings with a low thick walls are usually made from plastic, however, in this case, the ribs of stiffness should be provided to eliminate vibrations of the walls of the housing.

The manufacture of plastic cases of radio receivers on economic considerations is more profitable than wooden. Despite the technological and economic advantages of plastic masses for the manufacture of cases, the use of them is limited to broadcast receivers having large dimensions and high acoustic characteristics.

It is well known that the tree has good acoustic properties, so radio receivers

the highest classes tend to have wooden housings. For these considerations of the body of plastic masses are made only for Radios IV class and very rarely - for class III devices.

The chassis of the radio must have sufficient strength of the design, to withstand mechanical tests for impact strength, vibration resistance and strength during transportation. Application of methodsadopted in the furniture industry, i.e., the implementation of butt bonds with thickening compounds is not justified by economic considerations, as the technological process of manufacture is complicated, and therefore, the normative time for processing and assembly operations increases. Typically, the angular pairings of the walls of the broadcasting receiver enclosures are performed more simple methodswho do not cause technological production difficulties. For example, the walls of the housing are associated with bars or coal, pasted into angular joints, or using wooden planksinserted on the glue in the slots of the parts connected. Wooden walls can be combined with metal coal, brackets, straps, etc., and yet, despite the measures taken to simplify the technological processes of the manufacture of wooden housings, their cost remains relatively high.

The most laborious technological processes Fucking with wood veneer, varnishing and polishing of the housing surfaces. The process of polishing the assembled body is particularly difficult in angular compounds, since in these cases it is impossible to avoid manual operations. Naturally, therefore, that the efforts of designers and technologists should be directed to the creation of such a building structure, the manufacture of parts of which and the assembly processes would possibly be minimized. The most rational in this regard is the prefabricated design of the case when the individual parts of the simple form pass final processing and finish and then

mechanically combine into the overall design.

Fig. 37. Construction of the precast building.

There are other structures of collapsible buildings. One of the domestic radios produced a design in which the side walls are binding to metal panels with bolted joints. In this case, the radio chassis is an independent node that is not dependent on the construction of the housing.

Naturally, the examples of the examples are not exhausted all the possibilities of developing constructive design of detachable enclosures. One thing is obvious - similar designs are the most simple and cheap.

Building housing

For the manufacture of the housing, several sheets of the leaf of the arranged fiberboard of 3mm thick with the following dimensions were drunk:
- front panel measuring 210mm 160mm;
-the lateral walls of 154mm at 130mm;
- the upper and lower wall of 210 mm for 130mm;

- rear wall of 214mm at 154mm;
- Skulls for fastening the receiver scale of 200mm measuring 150mm and 200mm per 100mm.

With wooden bars, the box is glued together using PVA glue. After complete drying of the edge of the edge and the corners of the drawer are grouped to a semicircular state. Split irregularities and flaws. The walls of the drawer and the edges and corners are grouped. If necessary, again put sand and grind the box before receiving smooth surface. The scale window marked on the front panel cut out the finishing saw of the electrolyzka. Electrodel drilled holes for the volume control, knobs of setting and switching ranges. The edges of the obtained opening are also grinding. The finished drawer is coated with soil (car ground in aerosol packaging) in several layers with complete drying and equalize the irregularities of the sandpaper. Also, automotive enamel paint the receiver box. From a subtle plexiglass, cut the glass of the scale window and gently glue it from the inside of the front panel. In the end, try on the back wall and install the necessary connectors on it. On the bottom with the help of doublescrees, the plastic legs are dripping. Operating experience has shown that for the reliability of the leg, it is necessary to either glue tightly or secure screws to the bottom.

Holes for handles

Manufacturing chassis

The third version of the chassis is shown in the photos. The scale of fastening the scale is finalized to the indoor drawer. After refinement on the table, they are celebrated and done required holes For controls. The chassis is assembled using four wooden bars with a cross section of 25 mm by 10 mm. Bruks fasten the rear wall of the box and the scale fastening panel. For the attachment, postal nails and glue are applied. To the lower bars and walls of the chassis are glued horizontal panel Chassis with pre-made cutouts for placing a capacitance variable, volume controller and holes for setting the output transformer.

Electrical circuit diagram

maketling did not work for me. In the debugging process, refused the reflex scheme. With one RF transistor and repeated as the original UNF scheme, the receiver earned 10km from the transmitting center. EXPERIMENTS WITH POWER EXPERIENCE Low voltage, as an earthen battery (0.5 volt), showed insufficient power of amplifiers for loud-speaking reception. It was decided to raise the voltage to 0.8-2.0 volts. The result was positive. Such a receiver scheme was fast and in the two band variant installed in the cottage in 150km from the transmitting center. With a connected external stationary antenna 12 meters long, the receiver installed on the veranda completely voiced the room. But when the air temperature decreases with the onset of autumn and frost, the receiver moved to self-excitation mode, which forced to adjust the device depending on the air temperature in the room. I had to study the theory and make changes to the scheme. Now the receiver has been steadily worked up to temperature -15c. The fee for the stability of the work is a decrease in efficiency almost twice, due to the increase in transistor rest currents. In mind the absence of constant broadcasting, from the range of DV refused. This single-band variant of the circuit and is depicted in the photo.

Installation of the radio

Homemade printed circuit board The receiver is made under the scheme of the original and has already been refined in field conditions To prevent self-excitation. The board is installed on the chassis with a thermoclaus. For the shielding of the L3 choke, an aluminum screen connected to a common wire is applied. The magnetic antenna In the first chassis variants were installed at the top of the receiver. But periodically placed on the receiver metal subjects and cell Phoneswho violated the work of the device, so the magnetic antenna placed the chassis in the basement, simply by gluing it to the panel. KPU with an air dielectric is installed using the screws on the scale panel, the volume control is fixed there. The output transformer is used ready from the lamp tape recorder, assume that any transformer from the Chinese power supply unit will fit for replacement. The power switch at the receiver is not provided. Volume control is required. At night and on "fresh batteries", the receiver begins to sound loudly, but due to the primitive design of UNG, when playing, distortions are started, eliminating the volume. The receiver scale is made spontaneously. The appearance of the scale is compiled using the Visio program, followed by the translation of the image in a negative view. The finished scale was printed on dense paper with a laser printer. The scale must be printed on dense paper, with a temperature drop and humidity, office paper will do the waves and will not restore the former. The scale is completely glued to the panel. The arrow applied copper winding wire. In my version, this is a beautiful winding wire from the burnt Chinese transformer. The arrow is fixed on the axis with glue. Settings handles are made from covers of carbonated drinks. A pen the desired diameter Just with the help of the thermal stack glued into the lid.

Board with elements

Receiver assembled

Nutrition of the radio

As mentioned above, the "earth" version did not go. As alternative sources It was decided to use the "A" and "AA" format batteries. The farm constantly accumulates the seed batteries from lanterns and various gadgets. Sorted batteries with voltage below one volt and steel power sources. The first version of the receiver worked 8 months on one battery of the format "A" from September to May. Especially for nutrition from the batteries of AA format on back wall The container is glued. Small current consumption involves the power receiver from solar batteries Garden lanterns, but so far this question is irrelevant due to the reduction of power sources of the AA format. Organization of nutrition by throwing batteries and served as the name "Recycler-1" name.

Loudspeaker homemade radio

I do not urge to use the loudspeaker shown in the photo. But it is this box of distant 70s that gives the maximum volume from weak signals. Of course, other columns are suitable, but the rule works here - the more the better.

Outcome

I want to say that collected receiverhaving a slight sensitivity, not affected by the radio interference from televisions and pulse power sources, and the quality of sound reproduction from industrial am receivers is different puree and saturation. During all sorts of energy accidents, the receiver remains the only source of program listening. Of course, the receiver's diagram is primitive, there are schemes of better equipment with economical food, but this hand-made receiver works and with its "duties" copes. Exhaust batteries are working properly. The receiver scale is made with humor and jokes - no one notices for some reason!

Final video

This homemade VHF receiver I tried to make in the style of "retro". Front End from the car radio. Marking KSE. Next, the BC in the KIA 6040, UNG on the TDA2006, the speaker 3GD-40, in front of which the stretcher is 4-5 kHz, I do not know exactly, picked up for rumors.

Radio scheme

I don't know how to do digital setting, therefore it will be just a variable resistor, for this unit VHF enough 4.6 volts for full overlap of 87-108 MHz. Initially, I wanted to insert UNG on the P213 transistors, since the "retro" gathered and rebuilt, but he turned out to be too cumbersome, I decided not to show off.

Well, the network filter is installed, of course it does not hurt.

The right-hand indicator was not found, it was more accurate, but it was a pity to put - only 2 remained, so I decided to remake one of the unnecessary M476 (as in the ocean-209) - dispersed the arrow, made the scale.

Illumination - lED Strip Light. Venier is assembled from details of different radio receivers, from lamps to China. The whole scale with the mechanism is removed, its body is glued from many wooden detailsThe stiffness gives the textolit on which the scale is pasted and all this is drawn to the receiver body, in addition additionally pressing the front panels (those with a mesh), which are also removed if desired.

Scale under glass. Handles settings from some kind of radio with landfill, tinted.

In general, the flight of fantasy. I have long wanted to try the curvature of my hands, having built something like that. And here it was just nothing to do, and trimming plywood from repair remained, and the mesh turned up.

Hello everyone! Before you an article about making an unusual desktop radio naughty hands.

Cool when the appearance of the subject hides its functionality. In order to take advantage of this radio, you will have to turn on Sherlock Holmes or Miss Marpoul 🙂 First of all, the surrounding see a simple wooden sculpture that does not give any hints on what it is and how can it be used. Everything needs to be figured out experimentally.

To turn on / off, setting the range and change the volume, the radio receiver has two rotating rings lying on each other. Round base is a speaker to turn to turn on homemade.

Due to the spherical shape and distribution of weight, cleather Sustainably located on the table (the principle of the Vanka-stand). With the exception of electronic parts, the Radio "Ball" is fully made of wood. The case consists of wood layers different breeds (layers have different thickness).

Step 1: Design

After a long study, a dozen different sketches and brainstorming, I finally found the "perfect design". The setting will be carried out by rings, and not by potentiometers.

Step 2: Wood Selection

In the manufacture of housing crafts Was used different kinds Woods. Print templates, glue on wood and proceed to sawing and cutting out wooden blanks.

Step 3: Build "Ball"

Extlipped carved blanks.

Step 4: Enclosure

We install the workpiece B. lathe And start grinding. At the same time, be very careful. Why? After a second, I was "dumbfounded" by a breakdown of the workpiece on small piecesBut I was lucky and I was able to find every piece to glue the case together again. The cause of the gap is an unstabilized billet.

Step 5: Add electronics

Especially for crafts A simple radio set was purchased, which included two potentiometers (one to adjust the volume and on / off radio, the second to select the range).

In the inside there are fasteners under electronics. Potentiometers are installed in these attachments. Upper for sound, bottom to change the range.

When everything is prepared, polished and snapped parts together.