Homemade plastic case for umzch. Car amplifier. Amplifiers based on TDA2005, for low-power heads

Decent amplifier housing it can be done. Do it yourself, using simple hand tools. Using parts from ready-made devices with minimal alterations.
No new technologies or machines, just desire and a little skill.
The piece of iron is old, I made it 10-15 years ago, I didn’t photograph the process, but instead of the photographs I drew drawings. I did it for about six months in the evenings, partly at work, partly at home.
And one week in the evenings in the kitchen without cleaning and putting things in order, when my wife and daughter were away. I have made very significant progress this week, so I am revealing the secret.

But don't tell anyone!
I don’t even remember how I fell for this, maybe it was envy of the beautiful equipment from magazines, maybe I was already tired of the look of the available homemade products, I don’t know. Now I wouldn’t dare to do this, probably, after all, the work is decent and painstaking.

But looking at the amplifier now, I’m glad that I didn’t give up then, it turned out well, I’m pleased with the appearance.

In short, one way or another, it was necessary to build. I started construction by thinking about the purpose, layout and, of course, the appearance in general. It was the power amplifier that I was going to build; I had a preliminary one at that time, it was in a separate (wooden-plastic) case.
This entire appearance design and layout directly depended on existing or potentially available blanks and parts. Therefore, I first figured out what I had, what I needed to get, and how to combine it all to get what I wanted.

Well, since it’s a power amplifier, that means you don’t have to put anything on the front panel, except maybe a power button and a couple of some on/off indicators. This is nice - you don’t need to drill a lot of holes and figure out where to place them.

I chose a design where the network button is located in the center of the panel. Accordingly, I was going to install it right behind the front panel, and run the network cable to the button through the entire amplifier.

I have some parts attached to the front panel, and to facilitate the fastening process,
I placed a wooden panel between the ribs. Very comfortably.
I got several radiators, immediately cut off all the ribs on one side with a hacksaw, and brought them back to normal a little: I cleaned them, blunted the edges and chamfered them. The side on which the active elements should be attached was sanded more thoroughly. It is not necessary to grind everything smoothly, you can only grind the place where either the MC or the transistors will later become. Then I painted it (but only on the outside).

The length of the radiators was not enough to cover the entire depth of the case, so we had to extend it with another piece. That’s all. The radiators have run out, but we need a little more, about 60 mm.
Well, to hell with it, I didn’t look for radiators yet, I covered this place with a painted wooden insert.

All these parts of the radiators and the insert are fastened from above (from inside the amplifier) ​​with an aluminum angle.
In principle, here are the finished side walls. And from below this entire structure is screwed to the chassis.
And the chassis is a piece of hardware (epu) from the Vega 110 turntable. It also determined the depth of the amplifier. The iron there is good, moderately thick, the edges are bent (beaded), just what you need.

If you attach the radiators to the chassis, you already have almost a mock-up of the case on which you can install everything and test the amplifier.

What else remains for a full-fledged body? The back wall (in which you need to make a lot of different holes and fastenings), the top cover (with holes for ventilation), and somehow you need to refine the bottom of the amplifier - make a bottom and put the amplifier on legs.
The chassis itself is an unfinished structure; attaching the legs and bottom to it is inconvenient. And the appearance is “naked.” I had to make a frame from wood of a certain profile.

The frame is inserted into the chassis from below, and a plastic bottom is attached to the bottom of the frame itself in a quarter.

The bottom turned out perfectly from the plastic bottom of the same Vega 110.
The back wall and lid had to be cut from a single piece of some kind of duralumin. Scratched, and in places with potholes. I had to sweat... A hacksaw, a scraper, files, sandpaper - everything went into use.

Fastening the parts mainly with screws and self-tapping screws: radiators on the chassis with screws (I drilled holes in the radiators and cut threads, then M5 screws from below),
The rest is different, where are the screws, where are the screws.
The legs are screwed to the plastic bottom from the inside, and blocks are glued to the metal chassis below, in the places where the legs are installed. So that later, when finished, the bottom does not bend under the weight of the hull.
The bottom is attached to the frame with self-tapping screws. The frame itself is already attached to the chassis.

Initially, I drilled holes in the lid for ventilation. From memory, either 10 or 8 mm in diameter. In neat rows. It was only later, six months later, that I made the grids.
These are precisely the places where the mesh had holes.

I wanted to get rid of the visible fasteners on top as well, but it didn’t work out; I couldn’t come up with anything.
So I struggled a bit with adjusting the holes. Using a hand drill, I carefully adjusted the depth of the chamfer, little by little, so that the heads of the self-tapping screws would fit equally and flush.
The caps of the self-tapping screws are semicircular. In general, I tried to make it look “factory.”
The joint between the PP and the lid was made without self-tapping screws. There is a groove in the PP where the lid fits neatly into it.
Well... with the rear panel everything seems to be clear from the photo.

Everything is standard, only the “input level” knob was not immediately available. 4 input connectors and buttons next to them too. That comes later. This is the upgrade. To adjust the volume without preliminary, while the preliminary, well, let's say, is being moved or resoldered. At the same time, it became possible to quickly compare the sound with the preliminary one and directly.
I’ve been planning to replace the speaker terminals with more kosher ones for a long time, but I somehow don’t have the time, although I have everything.
The painting of the parts is more or less standard; I didn’t know much about the technology, so I painted it intuitively. I painted the radiators “hot-hot” - I applied nitro enamel to the heated radiator.
It holds more firmly this way. PP cover and other aluminum parts were primed before painting
powder diluted in a solvent. Powder - for powder coating of microwave oven housings.
As long as you don't scratch or beat roughly, everything holds together.

Everything is painted dark gray. A mixture of black nitro enamel + a little aluminum powder + something else colored to give the desired shade.
Photo of the insides.

In the rack

Preamplifier, UMZCH, sources.

That seems to be all.

Postscript: Naturally, not everything is written, many little things are missing. To write everything completely you need
a lot more writing, with emotions, experiences... many technical points were missed. Small things. But the main thing is here.

The easiest thing was to insert the prepared article into the portal editor. It took about 15 minutes at most. And this is exactly what I was afraid of most... The most difficult thing was to write an article.
Personally, I don’t really like it from the artistic side. I judge by fact. But that's how it is. I couldn't think of any other way.

If you're reading this, you've read it. Thank you!

The basis of any amateur radio design is a beautiful, comfortable case, especially since it should look decent on a device that takes its rightful place in the living room or your office.

CASE AND INSTALLATION

I struggled with the body for a particularly long time, until one fine day a stranger came to me. In his hands was a device that looked like an old power amplifier. The man introduced himself and started a conversation. It turned out that he knew me well and brought me an unnecessary thing to exchange for an uninterruptible power supply. He didn’t give him an uninterruptible power supply, but he persuaded him to sell the device for 400 rubles. Without thinking twice, he agreed.

The device is a compressor from the company TESLA , was in quite working condition, but all I needed from it was a housing that was just right for the amplifier complex.

VIDEO - HOMEMADE AMPLIFIER

The transformers were fixed to the board using especially strong “moment” glue; they were additionally pressed to the board with metal washers (with a rubber gasket so as not to pinch the windings), which had to be painted black so as not to be conspicuous. The washers are secured with bolts with a length of 40 mm and a diameter of 4 mm.

Power buses took almost 5 days. For a long time I couldn’t decide how to make them, from what material and what shape to make them. I tried a lot - aluminum, stainless steel (tires of the required section were available only from the specified metals). Both options were not suitable, there were too many losses, even buses with a cross-section of about 12 mm overheated, in the case of stainless steel there was a high resistance of the section of the used bus, within 5 minutes of operation of the inverters the bus heated up so much that you could easily boil water on it, resulting in losses only in tires - a modest 10 Amperes...

As a result, a thick stranded wire with a cross-section of 16 mm was purchased and each inverter was connected to the main contact bars through such a cable. The cross-section of this wire is more than enough, of course you can get by with a thinner one, but I made it with a reserve, so to speak, just in case.

The cable is connected to distribution buses (there are two such buses) - this is done for ease of installation. A power plus is supplied to each inverter through the distribution bus.

The distribution busbars are made of brass, secured to the main board with a bolt and glue (again, for insurance).

The heat sinks were taken from some domestic amplifier, after the first launch, it became clear that they were not enough for such a monster, because all the output stages of the amplifiers are mounted on this particular heat sink. That is why I decided to add active cooling in the form of a cooler.

Initially I thought of bringing the heat sink of low-power amplifiers outside, but then I found duralumin blanks in the attic and decided to make a heat sink out of them. Fortunately, the blanks had threads and there were no problems with their joining. The finished heat sink is attached to the amplifier chassis. A cooler is installed on the board of low-power amplifiers, but not to remove heat from the radiators of this unit, but to cool the power switches of the inverter and rectifier diodes. During operation at low power, the heat sinks of the inverters are cold, but at high powers they overheat quite significantly, since the amplifiers consume up to 700 watts, a considerable part of the power is lost turning into unnecessary heat generation on transistors.

Initially I thought of assembling a simple case, since the amplifier itself was planned for a car. Already at the end of the work I thought seriously about the design and all that came out were completely original solutions. The mixture of bronze and gold carbon fiber, the corporate logo and the design of the front panel are all made by hand. The volume control consists of three main parts; I initially planned to bring the regulators of the low-pass filter block outside, but after thinking a little, I realized that the design of the front panel was being spoiled, so I adjusted them in advance to my taste so that I no longer had to open the case. The cutoff frequency is approximately 70 Hz, the volume is at maximum - that's all.

I made brass busbars on the board for ease of installation, so that I don’t have to solder the main power busbars when I need to remove the board. Initially I thought that there would be few power buses, but then, when the amplifier was at the last stage of work, I realized that there would be more wires than planned. In order not to spoil the appearance of the internal installation, I decided to use wires with the same insulation color. I used almost all stranded wires with a cross-section of 2.5 mm; to fasten them I used special strips with a latch; a pack of such mounting strips costs a dollar, one pack was enough for the entire project (100 pcs).

All power parts of the amplifiers were mounted on the main heat sink through mica spacers, so as not to drill a hole for each transistor, I decided to use common steel plates, which are attached to the heat sinks with just one screw. This method presses the transistors quite well against the heat sink, and besides, God forbid, in case of breakdowns it will be convenient to work with the output stages.

And in the final part, we will see how the case looks from the outside, calculate the costs of creating a home amplifier, and also. Sincerely - AKA KASYAN.

Discuss the article HOME AMPLIFIER - CASE

This publication will talk about making the front panel for a homemade amplifier, and will also tell you a little about how I planned the amplifier case. I’ll tell you about a simple way to apply inscriptions to the metal surface of the front panel, as well as other useful things when planning and making a case for a homemade UMZCH.

Power amplifier housing

Before starting to design the amplifier case, I needed to solve the problem of choosing radiators for cooling the powerful KT825+KT827 transistors. The installed radiators will occupy a fairly large area in the body or on the body of the UMZCH. For every two channels of the UMZCH there are 4 transistors - a total of 8 transistors, you need to distribute them among the radiators.

At first I thought of installing all the transistors on two long radiators - 4 transistors for each, which would act as the side parts of the case, but I could not find a radiator profile of the required height and heat transfer area.

After digging through the household trash, compact radiators with a fairly large heat dissipation area were found, on which old KT805A transistors in a metal case were installed.

Rice. 1. Radiators from KT805A transistors.

Having slightly estimated the location of these radiators on the sides, I was already thinking about abandoning the idea of ​​​​using them, especially since there would be a lot of fuss with attaching the KT825, KT827 transistors in the TO-3 case; I would have to drill holes and remove a small layer of metal with a file or cutter.

At the same time, my father came to visit me in my room, and after talking a little about the housing for the ULF, I decided to use these radiators.

All transistors were installed on 8 radiators; for mounting, an insulated mounting with mica was used as a dielectric and heat conductor, and white thermal paste from the same KT805A that was originally installed on the radiators was used.

I talked about the isolated method of installing transistors in a TO-3 package on radiators earlier in an article on making an UMZCH circuit on the TDA7250.

Having the radiators available and playing a little with their location, I began to draw a plan for the amplifier housing in AutoCAD (now I use the free LibreCAD for drawing).

Good to know: to convert *.dwg files for AutoCAD into *.dxf format for LibreCAD and other programs, a converter program called “Teigha File Converter”, which is freely available under Windows, Linux, Mac OS X and Android, has proven itself quite well .

Rice. 2. Housing plan for a homemade amplifier in AutoCAD.

In terms of width, I tried to make the amplifier body the same as many domestic ULFs, for example, like that of Radiotehnika-U101. Thus, the width of the rear panel, on which the connectors and terminals of the amplifier will be attached, is 150mm.

The length of the amplifier case turned out to be equal to the length of three radiators + the thickness of the front panel. A toroidal transformer will be installed in the middle of the case, and then I’ll figure out how to place all the other electronics.

The rear panel should contain:

• 4 RCA connectors (tulip) for connecting signal sources;
• 4 fuse holders for AC + 1 fuse holder for 220V power supply;
• 1 IEC connector (like a computer power supply) for connecting 220V power;
• 2 terminal blocks WP4-7 for connecting 4 speaker systems;
• 1 COM port, in case I find time to do control via a computer.

I designed the placement of components on the rear panel the old fashioned way - on a sheet of paper in a box:

Rice. 3. Layout of connectors on the rear panel of the power amplifier, drawn on a piece of paper.

Rice. 4. Finished back panel for a homemade power amplifier.

All connectors and fuse holders were placed quite compactly and conveniently. Before attaching them, the panel with the cut holes was painted white using aerosol spray paint.

For the bottom of the amplifier case, an aluminum plate approximately 2mm thick was cut out to fit the resulting rectangle of radiators and rear panel.

For the future front panel of the power amplifier, a piece of duralumin 5mm thick, 75mm high and 450mm wide was cut out.

Rice. 5. Blanks for the amplifier case - radiators, rear panel, bottom and plate for the front panel.

Rice. 6. Housing of a homemade UMZCH assembled.

Amplifier Front Panel Layout

Having an almost finished amplifier case and a plate for the front panel, I began planning the latter, drawing what should be placed and how and in what dimensions.

On the front panel there are:

• Output power indicators - 4 rows of 9 LEDs (5mm) each;
• Power button;
• Two-color LED (5mm) - power and standby indicator;
• 4 switches PR 2-10, each with 10 positions - volume controls for each channel;
• 2 switches for the ability to disable any of the two pairs of channels;
• Headphone jack;
• Indication panel - component temperatures, modes, overload, fan status.

Rice. 7. Front panel plan for a homemade Phoenix P-400 power amplifier.

Rice. 8. Plan of the front panel of the amplifier with coloring and without dimensions (without headphone jack).

I liked this layout and decided to start implementing it, all that remained was to add some inscriptions and see how everything would look:

Rice. 9. Plan of the front panel of the amplifier with inscriptions for the controls.

Making the front panel of the amplifier

Having a clear plan and preparation, you can start working. With the help of sandpaper + effort + patience, all the depressions, paint residues and the consequences of slight oxidation were removed from the duralumin panel.

When eliminating surface defects, I made movements with sandpaper in the way that was convenient, that is, in different directions, in different directions and angles. Upon completion and after inspection, it was decided to perform additional (finishing) grinding, which would correct the cosmetic appearance of the plate.

To do this, it was necessary to repeatedly walk with sandpaper along the entire panel, evenly and in one direction (for example, from left to right). After such grinding, the plate looked quite neat and nice.

Afterwards, in accordance with the drawing that was drawn above, I began marking the places for drilling holes for the control and display elements using a ruler + square + compass + pencil. Before drilling, it doesn’t hurt to mark the locations for the holes with a core.

The holes for the LEDs were made with a drill with a diameter of 5 mm, as practice has shown, only a few holes had to be brought to the desired diameter of the LEDs using a small round needle file.

The holes for the switches (power supply and controls), button and jack were drilled with a drill of the maximum suitable diameter, but if you can’t find one, it doesn’t matter, a smaller one will do, then you can bring the diameter to the desired value using a round file.

There was one more difficult test left - to make a rectangular hole measuring 136x45mm for the amplifier display panel. Having weighed the choice of available means, I identified several solution options for myself:

• We drill holes with a diameter of approximately 5 mm around the entire perimeter of the rectangle, one next to the other. Then we get rid of the partitions between the holes and remove the cut piece of the plate. You can cut the partitions using a needle file or a jigsaw (stock up on nail files in advance). Afterwards, using files, we remove all the irregularities and align the shape of the cut rectangle as much as possible.
• This option came to mind after analyzing the previous one. Its essence is simple - we drill one hole, for example in the corner of a rectangle, gather all our patience, insert the jigsaw needle into the drilled hole and begin to cut out the rectangle along the drawn contour.

Having assessed the amount of fuss in the first and second options, I decided that the second option is simpler and will allow us to get a more accurate result. When I started, I didn’t even suspect that about two hours of hard work, about a dozen broken jigsaw files and several calluses on my hands awaited me... the desire to get the desired result helped me achieve my goal!

Everything turned out very neatly and I only had to slightly correct the entire perimeter of the rectangle using a flat file. I can’t recommend this option to anyone, since cutting metal with a diameter of 5 mm with a jigsaw is a very difficult task, perhaps even a little crazy. I used what I had on hand at that time; I definitely wouldn’t do that now - I would go somewhere to a factory and they would make everything much simpler.

Applying inscriptions to the front panel of the UMZCH

I think that this item will be of interest to many, especially those who make various housings for metal devices, not just power amplifiers.

I believe that many of you are familiar with or have at least once heard somewhere about such a phenomenon as Laser Ironing Technology (or simply popularly known as LUT), used for the manufacture of printed circuit boards at home.

I also heard about it at one time, but without even trying it for the manufacture of printed circuit boards (always, in the old fashioned way, a stencil was drawn by hand on a sheet of paper + a syringe with varnish for applying to PCB), I began to use it for applying inscriptions to metal.

The essence of the LUT methodology is very simple, now I will describe in detail how I applied inscriptions to the duralumin plate for the front panel of my homemade audio power amplifier.

We clean the metal with fine-grained sandpaper, ensuring that the surface is even and smooth (I have already done this, described above). We clean and degrease the surface of the plate using a cotton swab dipped in solvent.

We print out the required stencil on a LASER printer with all the necessary inscriptions and in several copies on a page taken from a durable glossy magazine.

Printing must be done in a mirror image, so that after interruption the inscriptions on the metal are in the correct position. You can display the image in any graphic editor or using the program in which the drawings were drawn.

Rice. 10. Stencil with inscriptions for the front panel of my amplifier.

If the printed design is quite large in size, then it may be better to cut it into smaller pieces. That’s exactly what I did - I separately cut out stencils with inscriptions on top, with drawings for each of the volume controls, headphones...

It is much more convenient to center stencils in small parts, especially those with circular holes. To do this, the inside of the paper of the prepared piece of stencil can be cut from the center to the edges and the resulting petals can be pressed into the hole, thereby reliably centering the stencil.

Rice. 11. Inscriptions printed on a magazine sheet of paper and in mirror image for the front panel of the UMZCH.

We heat up the iron. I also used a Soviet one with a solid massive metal sole; it cools down slowly and, accordingly, accumulates enough heat for heat transfer.

We heat a metal plate with an iron to a temperature slightly below the maximum temperature of the iron, this is done “by eye”, and the plate cools down quite quickly - you can heat it up to the maximum and then take a short pause before the next step.

In my case, the plate is quite long, so I transferred the inscriptions in order: I first heated one side of the plate, transferred the inscriptions, then started writing in the middle and heated the middle of the plate, and then the remaining side.

The process of transferring the inscriptions is very simple - we apply the stencil, center it and position it as needed, then we put the sole of the iron on top of the stencil and hold it there for 10 seconds, after letting it cool for 10 seconds we begin to gently “rub” the stencil over the entire area.

Having glued several stencils in this way, you can move on to the next stage. Of course, you can glue all the stencils at once, but it’s more convenient for someone, try it and determine the appropriate option for yourself.

We are looking for a container with dimensions sufficient to immerse the plate being manufactured; you can also use a bath.

We fill it with warm water with a temperature of approximately 30-35 degrees Celsius. Carefully immerse our plate with glued stencils into warm water.

We wait about 10-15 minutes so that the paper is completely soaked and easily peels off from the metal, separate it and wipe the panel with the inscriptions with a piece of dry cloth.

We wait a little while for the inscriptions on the panel to dry - thin layers of white fibers will become visible on them - these are remnants of paper. We remove these fibers using cotton wool soaked in alcohol, we do this carefully and with little effort.

We repeat the process of degreasing the metal in the next area where we need to glue the inscriptions (you never know, we still get it dirty with our hands), heat it with an iron, place the stencil, heat it, and then rub it in, soak it in water, wipe it... repeat until all the inscriptions are applied.

That's it, the inscriptions are ready!

It may happen that you won’t be able to get complete and high-quality inscriptions the first time - don’t despair, try and experiment.

I printed stencils on sheets of paper from different magazines, only two types of paper gave good results - they soaked well and peeled off from the toner transferred to the metal.

Varnishing and display panel

After applying all the inscriptions to the metal, the front panel was varnished using an aerosol can of clear varnish. I varnished it several times over two days. After waiting for everything to dry well, I began making a tablet with display elements.

Above I have given a plan of the front panel and it already shows indication LEDs, as well as digital indicators; in the middle there is an area for drawing a picture - a small Phoenix.

In principle, you can make an opaque panel and place everything as is, but I wanted something more interesting - the Phoenix will glow, and instead of protruding LEDs, the inscriptions will glow!

How to implement this? - print a film lining on which only the inscriptions, holes for digital indicators will be transparent and in the middle there is a translucent phoenix design.

I drew the basis of the stencil in AutoCAD, then converted it into a drawing and opening it in Photoshop, added a Phoenix drawing in the middle, and also added small turtle pictures that will glow red when the maximum set power is exceeded (these LEDs are connected to every 10th channel of the output LED indicators power).

Rice. 12. Stencil for the display panel of a homemade amplifier.

Icons with an exclamation point "!" will be highlighted when the speaker protection is triggered, as well as when the amplifier starts (speaker turn-on delay and click suppression).

The “On” inscriptions will glow green if the pairs of UMZCH channels corresponding to each side are turned on using the switches. The inscription “Fan” will light up when the cooling fans of the transistors of the UMZCH output stages start working. Icons with the index "t" are constantly highlighted under each of the digital segments, which display the temperature level from 9 to 0:

• For UMZCH transistors of the left pair of channels;
• For toroidal transformer;
• For amplifier chassis;
• For UMZCH transistors of the right pair of channels.

The solution with temperature levels looks a little confusing, but nevertheless quite informative. Now, if I were making a similar UMZCH, I would make the display with normal thermometers and on microcontrollers, and at that time, whatever came to mind from the budget and affordable options, I would implement it.

Having saved the drawing to a PDF file (Portable Document Format from Adobe), I went to the printing house, where within a few hours they provided me with the finished result in several copies on transparent film.

Rice. 13. A stencil printed on film for the amplifier display panel.

The display panel will be hidden behind a 3mm thick rectangular plate of organic glass (plexiglass), which will be placed in a rectangular hole in the front panel of the amplifier. Behind this plate will be placed a stencil printed on film, and behind it will be screwed an indication board with Phoenix backlighting, indicators and LEDs.

All display components must be placed on a printed circuit board, which must be designed to match the manufactured stencil. To design such a printed circuit board on a sheet of checkered paper, I printed out a stencil of the display panel, placed it on a sheet of paper with a future signet and marked what should be where, and later, using a pencil, I began to draw the tracks.

Rice. 14. How I once drew a printed circuit board for an indication panel.

To illuminate the picture with the Phoenix, small-sized yellow light bulbs with a voltage of 5V were used. It was possible to use yellow LEDs, but at that time I did not have enough of them.

If there are no yellow light bulbs or the glow is not sufficiently colored, then you can place a piece of bright yellow paper under the drawing in size - this will give an even and soft glow effect of the drawing.

Top cover for amplifier housing

With the top cover everything is quite simple - I cut it to the same size as the bottom of the amplifier. A large Titan cooler is installed in the middle of the cover to cool the transformer and the internals of the power amplifier.

Rice. 15. Titan cooler for cooling the power amplifier.

A protective mesh was later installed on the cooler, taken from a non-working PC power supply.

For efficient ventilation, four sets of holes, each with three rows, were drilled into the lid. They are placed equally spaced on the sides.

In order to make a hole in the cover for the fan, we used the method of drilling holes around the perimeter (in this case, a circle), which I wrote about above when making the front panel.

The top cover will be attached to the radiators using small knurled screws, this is very convenient if you need to remove the cover and replace the fuse or to clean dust - unscrewing six of these screws is a matter of minutes and no screwdriver is needed.

After all the holes were drilled, the panel needed to be painted. I decided to paint it black, since the knurled screws are silver and the cooler is also silver - they look good against a black background. I painted it in two layers, letting them dry enough, using an aerosol can with black paint.

Finishing touches and some notes

To use multi-position switches as step variable resistors (volume controls), the required resistances were selected experimentally.

Depending on the resistor values, you can make the adjustment linear or logarithmic - whichever you prefer.

Here is the connection diagram and resistance values ​​in my version of the regulators:

Rice. 16. Diagram of a step volume control based on a multi-position switch.

Four rubber feet with a height of approximately 13mm were screwed to the bottom cover of the case (bottom), this will allow you to install the amplifier on any surface without fear of scratching it, and will also add a slight dampening of noise from the case on which several fans rotate (important for quiet listening ).

You can also screw two handles to the sides of the front panel - this will make it more convenient to carry the amplifier, and it will add a plus to the appearance. The front panel is secured with four screws to the side radiators.

I sealed the holes with the screws with small black rubber bands - these are adhesive rubber feet that come with network switches (Networking Switch) of medium and high cost; I did not use them when working with switches, since the switches themselves were attached directly to the wall.

Result

Rice. 17. These are the inscriptions on the front panel of the amplifier.

Rice. 18. Appearance of the power amplifier assembly.

Rice. 19. Appearance of the power amplifier turned on with the fan grid installed.

Rice. 20. Rear view of the amplifier with connected signal cables, power cable and one speaker cable.

Rice. 21. Exterior view of the power amplifier on the right side.

At the end, you can also cover the sides with radiators and transistors with a thin layer of black paint from a spray gun, but I have not done this yet.

Conclusion

This is how it turned out to be a homemade product that still serves well today. When making this amplifier, I tried to put a part of myself into it, to make it original and at the same time simple and reliable to use. I think everyone interested will find something useful in this article.

Get creative, gain experience, try not to repeat the mistakes you’ve made before! Everything will definitely work out!

To assemble, you need to have a desire and a certain amount of free time, and you also need to always strive to ensure that you get a high-quality power amplifier that you can assemble with your own hands. In addition, you need to have certain knowledge and skills, and there are also financial costs.

However, the end result will be pleasing, and the amplifier will delight your ears with clean, transparent sound with plenty of power output. In the process of designing a car amplifier, you may encounter some difficulties in finding the necessary electronic components; in such cases, you can use their analogues. Creating a block design for sound amplification in a vehicle audio system, although the process is not fast, in the end it turns out to assemble five compact amplifiers, the total power of which will be 690 W. If desired, it is possible to increase this value to 760 W. p>

Necessary device requirements

First you need to decide on the technical characteristics that you expect to get in the final result. As a rule, this is high sound quality, high output power, a technologically simple design that creates ease of use, low cost, the ability to work with twelve dynamic drivers and a subwoofer. Such requirements can be obtained by making DIY car amplifier in the amount of five pieces, of which one should work for the subwoofer. The optimal solution to this problem is to manufacture a separate power amplifier according to the Lanzar circuit diagram.

To assemble such a device, you will need four microcircuits, namely two TDA 7384 - 4x40W and two TDA 2005 - 1x20W. These microcircuits are intended to power the front speaker system. This schematic solution is the most economical in terms of monetary costs.

Efficient voltage converter

IN car sound amplifier The most important and at the same time time-consuming part is the voltage converter. Therefore, it is from this block that you should begin assembling the entire sound amplifier complex. The well-known push-pull pulse-width modulation controller of special precision - TL494 - is used as the converter's pulse generator. If such a microcircuit is not available, you can use its analogue - 1114EU3/4. The microcircuit does not have a separate output amplifier. In each arm of the converter cascade, a pair of powerful IRF3205 field-effect transistors are installed on heat sinks, which are secured through an insulating gasket using heat-conducting paste. Radiators for this purpose can be used from computer power supplies.

The rectifier circuit uses KD 213A diodes with a maximum current of 10 A, but they do not require additional cooling. In addition, you will need a pair of electromagnetic relays designed for an operating current of 20 A, but to be sure, it is better to set it to 50-60 A. The voltage converter has a remote control function, which is undoubtedly an effective device, since when controlling the power and turning on the subwoofer, no additional installation of powerful switches. When positive voltage appears on the remote control, the relay is instantly turned on and power is supplied to the converter.

Collect DIY car sound amplifier in principle, not very difficult, but some difficulties may arise during the manufacture of the transformer, that is, if there are no ferrite rings available, then you will have to look for old, suitable power sources. Power supplies from a computer are excellent for these purposes. There, too, you will have to do a little magic, since the two halves of the ferrite rings are securely glued together, to separate them you need to slightly heat the joints with a lighter, and then carefully remove them from the frame and remove the standard windings. Before we start winding the winding we need, we need to remove the side walls of the frames and then connect them to each other so that we get one long frame on which all the necessary turns of the windings can easily fit.

The primary winding is wound at the rate of ten turns with a midpoint (2 x 5 V) with five strands of enamel wire with a diameter of 0.8 mm. It’s easier to do this: I wound 5 turns along the entire length of the frame, made a tap, and insulated the winding with varnished cloth, then wound another five turns on top. Next, you need to perform phasing, that is, connect the beginning of the first winding to the end of the second. The junction of the ends is the tap to which positive voltage from the general power supply will be supplied. After the phasing has been done, you can begin winding a test secondary winding with any number of turns, with the help of which we will determine the correct phasing.

When the converter is connected to the network, the transformer should not overheat at idle and not emit extraneous sounds such as buzzing; the transistors should remain cold. Next, we connect an incandescent lamp to the secondary winding circuit, and it should glow at full heat, and the transistor should not heat up, only over time it warms up a little. If after this test there are no problems, then remove the test winding and wind the normal one.

Assembly of the structure

The case was purchased for the JLH1969 headphone amplifier from the review -
From the variety of housing options available offline and online in terms of size, price and design, I decided to buy this one on Ali.

The Chinese company Breeze Audio produces many different versions of aluminum housings for homemade products. The cases are generally inexpensive, but the cost of shipping the case usually adds up.

Product characteristics:
Outside dimensions: 189mm * 220mm * 45mm
Inside dimensions: 177mm * 200mm * 41mm
Front panel thickness: 6mm
Rest: 3 mm

Case weight: 0.7 kg

Dimensions and weight correspond to specifications.

The seller took a long time to send. It also took a long time.

The box arrived:

Everything inside is packed in protective material:


I thought there was an assembled case inside. But that's not true. Everything has been taken apart piece by piece. Everything was done carefully.




Packed in Chinese newspaper. A newspaper like ours “From Hand to Hand”.

Accessories:



The fittings were supplied with a large supply. Velcro legs are attached tightly. The screws on the front panel are hexagonal. The rest are ordinary ones for a Phillips screwdriver. All screws are M3. The volume control knob is also made of aluminum and is attached to the potentiometer knob with a very small screw on the side. You need a very small screwdriver..html) it will fit. But the hole in the body needs to be bored or drilled out.

Power button with lock included. One pair of contacts for making and breaking. If desired, the button can be replaced with your own to open both power wires. The rear panel has a power connector with a built-in fuse.

But I still replaced it with a power connector with a fuse and an EMI filter. I had to drill out the nest a little. On the back panel there is a hole for the female RCA connector.

Everything is assembled quite simply. Everything is accurate. The screws hold the panels tightly. Mounted the amplifier into the housing. This is how it happened:









I haven't written any inscriptions on the front panel yet. I saw online a description of applying inscriptions with LUT technology and then coating the panel with Plastik 71 acrylic varnish for printed circuit boards from a spray can. Let's see. Maybe I’ll leave it like this without labels. Everything is clear anyway. I couldn't figure out how to put the inscriptions on the back black panel. For now I marked the right channel with electrical tape.

Pros of the case.
High-quality metal processing
Not a bad design
Rich fittings

Disadvantages of the case.
Price
Aluminum body - front panel is susceptible to scratches and oxidation.
Painting the body. With a small scratch, the paint peels off and the aluminum begins to shine.

Began. First scratches on the top cover

It is better not to install anything on such cases, but to move them carefully. Place it in one place and use the device.
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