Cases for homemade radios in retro style. We make cases at home. Electrical circuit of the radio receiver

I tried to make this homemade VHF receiver in the retro style. Front End from the car radio. KSE marking. Next, the IF block on the KIA 6040, the VLF on the tda2006, the 3GD-40 speaker, in front of which the notch at 4-5 kHz, I don’t know for sure, I picked it up by ear.

Radio receiver circuit

I don’t know how to do digital tuning, so it will be just a variable resistor, for this VHF unit, 4.6 volts is enough to completely cover 87-108 MHz. Initially, I wanted to insert ULF on P213 transistors, since I assembled and rebuilt the "retro", but it turned out to be too bulky, 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, but it was a pity to put it - only 2 remained, so I decided to redo one of the unnecessary M476 (as in Ocean-209) - straightened the arrow, made a scale.

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

Scale under glass. The tuning knobs are from some junkyard radio, touched up.

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

Radio receiver housing, decorative and protective elements

The acoustic characteristics of the radio receiver are determined not only by the frequency characteristics of the low-frequency path and the loudspeaker, but to a large extent depend on the volume and shape of the case itself. The body of the radio receiver is one of the links in the acoustic path. No matter how good the electro-acoustic parameters of the low-frequency amplifier and loudspeaker are, all their advantages will be reduced if the radio receiver case 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 closed with a radio fabric or a decorative grille. Finally, to protect the listener from accidental damage when touching conductive parts, the chassis of the radio receiver in the housing is protected by a rear wall on which a power circuit blocking is installed. Therefore, decorative and protective structural elements that are elements of the acoustic path, as well as methods for their mechanical fastening, can have a significant impact on the quality of reproduction of sound programs. Therefore, we will consider each structural element of the broadcasting receiver housing separately.

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

To meet the first requirement, the housing must provide good reproduction of the low and high frequencies of the radio's 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, the loudspeaker diffuser is considered as a piston oscillating in the air, creating areas of high and low atmospheric pressure during forward and reverse motion. Therefore, it is far from indifferent in which case the loudspeaker is located: with an open or closed rear wall. In a housing with an open rear wall, air thickening and rarefaction 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 decreases to zero.

An increase in the depth of the hull according to the design requirements is quite acceptable. The dimensions of radio receivers with several loudspeakers cannot be calculated using the above formulas. In practice, the dimensions of enclosures with multiple loudspeakers are determined experimentally from the results of acoustic tests.

The design of cases of broadcasting receivers in the desktop version with a closed back wall is usually not used. This is explained by the fact that it is very difficult and impractical to design radio receiver cases with a closed volume, since the heat exchange mode of radio components worsens. On the other hand, tightly closed back enclosures tend to increase the resonant frequency of the loudspeaker and cause uneven frequency response at higher frequencies. To reduce uneven frequency response at high frequencies inner side The body is upholstered with sound-absorbing material. Naturally, such a complication of the design can be allowed only in radio receivers of the highest classes, in furniture design with remote acoustic systems.

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

Table 3

As can be seen from Table. 3, depending on the class of the radio receiver, the norms of the frequency range of the entire amplification path in terms of sound pressure also change. Therefore, it is not always advisable for all classes of radio receivers 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, but increases their cost, since the loudspeaker is selected in accordance with GOST standards, which determines the range of reproducible frequencies. For these reasons, there is no need to improve the acoustic characteristics of the cabinet, 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 makes it possible to reduce the cost of the low-frequency amplifier design.

According to statistics, the cost of a wooden case is from 30-50% of the total cost of the main components of the receiver. The relatively high cost of the hull requires the designer to be careful in choosing 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 from separate pine boards laid between two thin sheets plywood. Front sides the hulls are glued with fine wood veneer, varnished and polished. At the same time for hull manufacturing class III and IV radios use cheap plywood, non-deficient wood veneer, textured paper or plastics. Metal cases are not currently used due to non-

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 case, knowing the cost of the hull 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 case for a certain technological process, its exterior finish, the unit cost has a constant specific value. For example, in the manufacture of receiver cases at a specialized enterprise or in workshops, the unit cost is 0.11 kopecks. This value of the unit cost 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 hull corresponds to well-defined materials and technological processes. The value is 0.11 kop. refers to cases made of plywood, pasted over with cheap veneer (oak, beech, etc.) and varnished without subsequent polishing. For cases carefully polished and pasted over with more valuable wood species, the unit cost increases by approximately 60% - Thus, to determine the cost of a wooden radio case, it is necessary to multiply the unit cost by the amount of material (plywood) used.

The process of pasting the body of the radio receiver with precious woods and subsequent polishing is quite laborious, as it involves many manual operations, requires large areas for its processing and tunnel ovens for drying the treated surfaces. In order to save veneer, which is in short supply for a number of enterprises, it is replaced with texturized paper, on which a pattern of fibers is applied. tree species. However, pasting radio receivers with texturized paper does not improve the situation, since to create a good presentation, multiple varnishing (5-6 times) is required, followed by drying.
in tunnel ovens. In addition, an additional operation is introduced - painting the corners of the body, where sheets of texturized paper are joined. The cost of hulls finished in a similar way, does not decrease 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 presented to the acoustic system of the radio receiver. Unfortunately, the technical literature lacks detailed information about the choice of material grade and its effect on the acoustic parameters of receivers. Therefore, when designing hulls, one can only be guided by summary presented in the work. For example, in high-end radio receivers for reproducing 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 joinery 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 sound pressure of the order of 0.8-1.5 n / m2, a plywood thickness of 8-10 mm is allowed. Enclosures for acoustic systems radio receivers of classes III and IV, having a cutoff 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. Casings with small wall thicknesses are usually made of plastic, however, even in this case stiffening ribs must be provided to eliminate vibrations of the casing walls.

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

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

the upper classes tend to have wooden hulls. For these reasons, cases made of plastics are made only for class IV radio receivers and very rarely - for class III devices.

The body of the radio receiver must have sufficient structural strength, withstand mechanical tests for impact strength, vibration resistance and strength during transportation. Application methods, adopted in the furniture industry, i.e., the implementation of butt connections using spiked 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. Usually, the angular interfaces of the walls of the housings of broadcasting receivers are performed more simple methods, which do not cause technological production difficulties. For example, the walls of the case are connected with bars or squares glued into the corner joints, or with the help of wooden planks inserted with glue into the slots of the parts to be joined. Wooden walls can be connected with metal squares, brackets, strips, etc. And yet, despite the measures taken to simplify the manufacturing processes wooden cases, their cost remains relatively high.

The most labor intensive technological processes are pasting with wood veneer, varnishing and polishing the surfaces of the case. The process of polishing the assembled body is especially difficult in corner joints, since in these cases it is impossible to avoid manual operations. 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 hull design, when individual parts of a simple shape undergo final processing and finishing, and then

mechanically combined into a common structure.

Rice. 37. The design of the prefabricated body.

There are other designs of collapsible buildings. 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 above examples do not exhaust all the possibilities for developing design designs for detachable housings. One thing is obvious - such designs are the simplest and cheapest.

Hi all! Many radio amateurs, after they have done their next craft, face a dilemma - where to “shove” all this, and so that later people would not be ashamed to show it. Well, with cases, let's say at the present time, it's not so a big problem. Now you can find many ready-made cases on sale, or use suitable cases for your designs from any radio equipment that has failed and disassembled into parts, also use building materials in your crafts, or whatever comes to hand.
But to give, so to speak, a “presentation” of its design or to please the eye, at home, is the problem of more than one radio amateur.
I will try to briefly describe here how I make front panels for my crafts at home.

To design and render the front panel, I use free program FrontDesigner_3.0. The program is very simple to use, everything becomes clear immediately, in the process of working with it. It has a big library sprites (drawings), she is something like Sprint Layout 6.0.
Which are now the most accessible for a radio amateur sheet materials- this is plexiglass, plastic, plywood, metal, paper, various decorative films And so on. Everyone chooses for himself what is more suitable for him in terms of aesthetic, material and other conditions.

1 - I pre-think and put in place what I will have installed on the front panel in my design. Since the front panel is a kind of “sandwich” (plexiglass - paper - metal or plastic) and this sandwich needs to be fastened together somehow, I use the principle - how will it all be held and in what places. If mounting screws are not provided on the panel, then only nuts for fastening connectors, variable resistances, switches and other fasteners remain for this purpose.

I try to distribute all these elements evenly on the panel, for reliable fastening of all its constituent parts between themselves and fastening the panel itself on the body of the future design.
As an example - in the first photo I circled the mounting points of the future power supply with red rectangles - these are my variable resistances, banana sockets, a switch.
In the second photo, the second version of the power supply - everything is the same. In the third photo of the next version of the front panel - these are LED holders, enconder, sockets, switch.

2 - Then I draw the front panel in the FrontDesigner_3.0 program and print it out on a printer (I have a b/w printer at home), so to speak, a draft version.

3 - From plexiglass (also called acrylic glass or just acrylic) I cut out the blank for the future panel. I take plexiglass mainly from advertisers. Sometimes they give it away anyway, and sometimes they have to take it for money.

5 - Then, through these punctures, I make markings on acrylic (plexiglass) and on the body of my future design with a marker.

6 - I also make markings on the case for all other available holes on the panel, for indicators, switches, etc.

7 - But how to fix an indicator or display on the front panel, or the body of the structure?? If the body of the structure is made of plastic, then this is not a problem - I drilled a hole, countersunk it, put countersunk screws, support washers under the display (or tubes) and that's it, the problem is solved. And if the metal, and even thin? It won’t work like that here, it’s perfect flat surface under the front panel in this way do not get and appearance will no longer be the same.
You can of course try to fit the screws with reverse side cases and on thermal glue or glue with "epoxy", as you like. But I don’t like it so much, it’s too Chinese, for my beloved I do it. So here I do things a little differently.

I take countersunk screws of suitable length (these are easier to solder). I tin the screw attachment points and the screws themselves with solder (and flux for soldering metals), and solder the screws. On the reverse side, it may not be very aesthetically pleasing, but it is cheap, reliable and practical.

8 - Then, when everything is ready and all the holes are drilled, cut and processed, the panel pattern is printed on a color printer at home (or at a neighbor's). You can print a drawing where photographs are printed, you first need to export the file to a graphic format and fit its dimensions to the intended panel.

Then I collect all this "sandwich" together. Sometimes, so that the nut from variable resistance is not visible, you have to cut off its stem a little (grind off the shaft). Then the cap sits deeper and the nuts from under the cap are practically invisible.

9 - Look at some of the front panels of my designs, some of which are also shown at the beginning of the article under the title. Maybe, of course, not "super-duper", but quite well, and it will not be a shame to show your friends.

P.S. You can make it a little easier and do without plexiglass. If color inscriptions are not provided, then you can print the drawing of the future panel on a black and white printer, on colored or white paper, or, if the drawing and inscriptions are in color, then print it on a color printer, then laminate the whole thing (in order not to paper quickly slammed) and stick it on a thin double-sided tape. Then the whole thing is attached (glued) to the body of the device in place of the intended panel.
Example:
An old printed circuit board was used for the front panel. The photographs show what the initial version of the design was like, and what it became at the end.

Or here are a couple of designs where the front panel was made using the same technology

Well, that's basically all I wanted to tell you!
Of course, everyone chooses for himself the paths available to him in his work, and in no case do I force you to accept my technology as a basis. It's just that maybe someone will take it, or some of its moments into service and just say thank you to me, and I will be pleased that my work was useful to someone.
With respect to you! (

A simple technology for the manufacture of housings for amateur radio designs do it yourself

Many, especially beginner radio amateurs, are faced with such a problem as the selection or manufacture of a case for their design. They are trying to place the assembled board and other components of the future design in cases from old receivers or toys. In its finished form, this device will not look very aesthetically pleasing, extra holes, visible screw heads, etc. I want to show and tell by example how, in just a couple of hours, I make a case for a recently assembled SDR receiver.

Let's get started!

First we need to make a fixture for fixing the parts of the future case. I already have it ready and I have been using it with success for ten years. This simple device will come in handy for precise gluing of the side walls of the case and maintaining angles of 90 degrees. To do this, you need to cut out parts 1 and 2 from plywood or chipboard, at least 10 mm thick, as in photo 1. Of course, the dimensions may be different, depending on which structures you plan to manufacture in the future.

photo 1:

The case will be made of plastic 1.5 mm thick. To begin with, we measure the highest details of the structure, I have bulky capacitors on the board (photo 2). It turned out 20 mm, let's add a textolite thickness of 1.5 mm and add about 5 mm for racks into which self-tapping screws will be screwed when I fix the board in the case. In total, the height of the side walls is 26.5 mm, I do not need such accuracy and I will round this number to 30 mm, a small margin will not hurt. We write that the height of the walls is 30 mm.

photo 2:

My measurements printed circuit board 170x90 mm, to this I will add 2 mm on each side and I will get dimensions of 174x94 mm. We write that the bottom of the case is 174x94 mm.

Almost everything is calculated and I start cutting blanks. When working with plastic, it is convenient to use a mounting knife and a ruler. Literally after 10 minutes, I got the back wall and side wall blanks (photo 3).

photo 3:

Next, we clamp back wall into our previously made “device” and glue the side wall, which in my case has a size of 177x30 mm (photo 4. a). As well as the first wall, we glue the second one by turning the blanks on the other side (photo 4. b). To glue the walls of the case, “Superglue” is used (for greater strength, you can then walk around the corners glue gun, also all wires can be bundled and glued to the walls of the case).

photo 4:

Photo 5 (a) shows the result of my work. When the side walls are correctly glued and the angle of 90 degrees is maintained, you can easily glue the remaining 2 walls and mounting posts for mounting the board. In my version, one wall is blank, and the second with holes for connecting connectors (photo 5 b).

photo 5:

After gluing the entire body, it should be rounded off with a needle file or sandpaper all corners, this will give the case smooth lines and it will not look like a brick. After everything is ready, the board is installed, with a few drops of glue we glue the cover of the device (photo 6).

photo 6:

Well, the fully assembled receiver in the case (photo 7) is now mounted on the wall, does not interfere or spoil the interior of my workplace.

photo 7:

That's all! I spent a couple of hours on all the plumbing work, and my wife’s first question was: “what kind of alarm do we have?” (joke!)
Success in creative work!