Printed circuit boards of amplifiers in lay format. Drawing boards in Sprint-Layout correctly from the first steps. Difference in housings

Despite the simplicity of this program, I am often asked to write an article on it. But I had no time for everything. Therefore, the role of Captain Obvious took over Sailanser... Having completed this titanic work. I only corrected it, but added some details here.

Everyone has probably known for a long time a program for the manufacture of printed circuit boards called Sprint-Layout, at the moment the latest version is proudly named, 5.0

The program itself is very simple and does not take much time to master, but it allows you to make boards of a sufficiently high quality.

As I said, the program itself is quite simple, but it has many buttons and menus to help us in our work. Therefore, we will divide our lesson in drawing a board into how many parts.
In the first part, we will get acquainted with the program and find out where and what is hiding in it. In the second part, we will draw a simple board, which will contain, for example, a pair of microcircuits in DIP packages (and we will make these microcircuits from full zero), several resistors and capacitors, and also see such an interesting feature of the program as Macro creator and use it to make a microcircuit case, for example TQFP-32.
I will also show you how to outline the board from a picture or photograph.

Part 1: What and where we hide and how it helps us in drawing the printed circuit board.

After we have found the program, downloaded it, unpacked it from the archive and launched it, we see such a window.

First, let's see what we have hidden behind the File.

We click on this inscription, and immediately we have a drop-down menu.

New,Open,Save,Save as, Printer settings ..., Seal…, Output With this brother, everything is clear anyway. Tea is not the first day we sit in Windows.
Save as Macro ... This option allows us to save the selected fragment of the schematic or other details as a macro, which has the extension .lmk, so as not to repeat the steps to create them again in the future.
Autosave.... In this option, you can configure the autosave of our files with the .bak extension and set the required interval in minutes.
Export In this option, we will be able to export to one of the formats, i.e. save our scarf as a picture, as a gerbera file for further transfer to production, save it as an Excellon drill file and also save it as contour files for subsequent creation of a scarf using a CNC machine. Usually comes in handy when preparing for factory production.
Directories ... In this option, we can configure the parameters of working with the program, such as a keyboard shortcut for file locations, macros, layer colors, etc.

Go to the next item Editor

The next item we have is Action

Next on the list we have Options.

So, the first point, we have to configure the main parameters. We can specify the units of length in our case mm, indicate the color of the hole in the contact pad, in our case it matches the background color and will be black; if later our background is red, then the color of the hole in the contact pad will also be red. Alternatively, you can simply choose the color of the hole white, and it will be white no matter what background we have.
The second item we have is Virtual nodes and traces, this item, if it is checked, gives a very interesting property in the program, it puts on the explorer which we draw several virtual nodes.

And the program will automatically add a few more virtual nodes in the sections between the real nodes and we have the opportunity to further edit our track. This is very convenient when you have to drag the third track, for example, between two already laid ones.

Mirror macros and back text
If this item is activated, then when inserting a text or a macro on a layer, the program will itself look to mirror it or not so that later the details or inscriptions have the correct display on our finished board.

The next item we have is the Board Map, this item has one interesting joke, if it is activated, then a small window appears on the left side of our program.

It's like a miniature copy of our scarves, whether to include it or not, it's up to everyone to decide for me personally. Fans of the RTS genre will also appreciate :)

Pop-up windows are basically all sorts of hints in the program - obviously.

Limit font height (min 0.15mm)
This is the tick that many beginners are looking for, and not only users of this program, if it is worth it, when we write on the board or on the elements, then we cannot make the size of the letters less than 1.5 mm. So if it is necessary, somewhere to put the text less than 1.5 mm in size, then I recommend removing it. But when sending to production, this must be taken into account. Silk-screen printing of such a small resolution cannot be printed everywhere.

Go ahead and see another interesting fad, namely Ctrl + mouse to memorize the parameters of the selected objects if this item is activated, then one interesting thing appears. For example, we drew two contact pads and laid a track between them, say 0.6 mm wide, then did something else and something else, and in the end we simply forgot what the width of this track was, of course, you can just click on it and in the track width setting we will display its width,

here, instead of 0.55, our width will become 0.60, but then it's lazy to tweak the slider to the right of the number in order to adjust the width by 0.6, but if we click on the same track with the Ctrl button held down, then our value is 0, 6 will be immediately remembered in this window and a new track, we will draw already 0.6 mm thick.

Using a step of 0.3937 instead of 0.4.
The translator is, of course, very clumsy in the original, this item is written like this HPGL-Skalierung mit Faktor 0.3937 statt 0.4 in general, this item is responsible for creating an HPGL file for subsequent transfer to the coordinate machine, and indicates whether to use one decimal place or, depending on the machine, use four characters after the comma.

We have finished with the first point and will now move on to the second point of our window, it is called Colors for us and let's see what is hiding there.

There is nothing special here either, we just indicate the paths where and what we have located, this setting takes place if we install the program from the distribution kit downloaded from the official website, but because the program works great for us and without any installation, then we just need not change anything and go further.

Here, too, everything is quite simple and we just indicate the number to which the program will be able to roll back the changes, if where something was screwed up when drawing our board, I set the maximum number 50.

We move on to the next item, and we call it I max here they show movies in 3D format

In it, we see keyboard shortcuts for certain operations and if something we can change them, although I didn't really bother with this and left everything as it is by default.

We are done with the Settings item and see the rest of the drop-down menu options Options

Properties
If we select this item, then a window will open on the right in the program.

Which will allow us to control our drawn shawl to put constraint gaps, etc. An arch-convenient and extremely necessary thing. Especially when sending boards for production, and even in artisanal conditions, it comes in handy. The bottom line is what. We set, for example, the minimum clearance of 0.3mm and the minimum track not less than 0.2mm, and during the DRC check, the program will find all the places where these norms are not met. And since they are not fulfilled, then there may be jambs in the manufacture of the board. For example, the tracks stick together or some other problem. It also checks hole diameters and other geometric parameters.

Library
When we select this item, we will see another window on the right side of the program.

A very interesting point, it allows us to put a picture in the background on our table in the program where we draw a scarf. I will not describe it in detail for now, but I will return to it.

Metallization
When this option is selected, the program fills us all the free area with copper, but at the same time leaves gaps around the drawn wires.

These gaps can sometimes be very useful to us, and the board with this approach turns out to be more beautiful and more aesthetic, where I will also dwell in more detail on adjusting the width of the gap when we draw the scarf.

Whole board
We select this option, the scale will decrease on the screen, and we will see our entire scarf as a whole.

All components
Similar to the top point, with the only difference that it will zoom out depending on how many components are scattered over the scarf.

All selected
This item will adjust the screen size up or down depending on which components are currently selected.

Previous scale
Return to the previous scale, everything is simple.

Refresh Image
A simple option just updates the image on our screen. Useful if some visual artifacts have appeared on the screen. Sometimes there is such a glitch. Especially when copying and pasting large pieces of schematic.

About the project…
If you select this option, then you can write something about the project itself, and then remember, especially after yesterday, that I drew there, then it looks like this.

Here we see that we drill 56 holes and we need to adjust five of them so that the inner point on the contact pad is 0.6 mm.

Macro creator ...
A very, very, very, useful item in the program that allows us to draw a complex corpus, such as SSOP, MLF, TQFP or some other in a minute or two. When you click on this item, such a window will open.

Here we can select and customize the drawing of our case, looking at the data from the datasheet for this or that microcircuit. We select the type of sites, the distance between them. Location type and oops! There is a ready-made set of pads on the board. It remains only to arrange them on the silk-screen layer (for example, to frame them) and save them as a macro. Everything!

The following points, such as Registration and a question mark, that is, I will not describe the help because there is absolutely nothing in them that will help us in the further drawing of our scarves, although the help will be useful to those who are friends with the German language.

Uf described the same little items in the drop-down menus, but all these items have their own pictograms in the form of pictures on the panel just below, that is, all the options necessary for the operation of this panel are taken there.

I will not dwell on it in too much detail, because it duplicates menu items, but during further drawing I will simply refer to these icons so as not to obstruct the perception with phrases like, Select the menu item File, New.

As I said, I will describe these icons, I will move from left to right and simply list them if the icon has some thread setting, then I will dwell in more detail.
Let's go from left to right New, Open file, Save file, Print file, Undo action, Repeat action, Cut, Copy, Paste, Delete, Duplicate, Rotate and here we will make the first stop, and look at this item in more detail, if you choose which one then the component on our shawl and click on the small triangle next to the rotation icon, then we will see the following.

This is where we can choose the angle to which we rotate our part, as I said above, it was by default 90 degrees and here it is 45 and 15 and 5, and we can even put our own, for example, as I set 0.5, that is, half a degree.
Now let's have fun! We put the complete sets on the board, unfold it at random, at arbitrary angles. We spread all this with crooked lines ala Topor and brag to friends about stoned boards with psychedelic wiring :)

At this point, I will also dwell in more detail, the point is actually very good, it helps to give a beautiful and aesthetic look to the scarf so that in the future you can boast to your friends how everything is neat and beautiful for you, for example, we put SMD parts on our board and they are all at random and viscous. for snapping to the grid, and then select a few details and choose alignment to the left and everything looks neat.

Refresh, Template, Properties, Control, Library, About and Transparency
Transparency is also quite an interesting point, which allows you to see the layers, which is especially useful when making a double-sided board and a lot of wires on each layer, if you press this button it will look something like this.

In it, let's go from top to bottom.
Cursor When you click on this item, it simply represents a cursor that allows us to select some element on the board and drag it across the board while holding the left mouse button
Scale When you click on this icon, the pointer will change to a lens with plus and minus signs at the edges and, accordingly, if you press the left mouse button, the image will enlarge, if the right, then it will decrease. In principle, when drawing shawls, this item can not be selected, but scroll the mouse wheel forward or backward, respectively, the scale will increase and decrease backward.
Conductor When this icon is selected, the pointer changes to a dot with a cross and allows us to draw a track from one pad to another. The track is drawn on the active layer, which is selected at the bottom.

If you select the line "with metallization", the contact pad will change color to bluish, with a thin red circle inside, this will mean that metallization is taking place in this hole and that this hole is transitional from one side of the board to the other. It is also very convenient to put such contact pads on double-sided boards, because during the subsequent printing, these contact pads will be printed on both sides of our future board.
SMD contact When you select this icon, it becomes possible to place small smd contacts on our scarf.
Arc This icon allows us to draw a circle or draw an arc.

This is especially true for those who make their scarves using LUT technology and for whom, when printing on a laser printer, the printer does not make large painted areas perfectly black. In the settings, you can also choose the thickness of the border to adjust the roundness of the corners of our polygon.
Figure
If you select this icon, then a window opens from which you can draw or what kind of thread a figurine, or you can depict a fancy spiral.

Compound
When you select this icon, the pointer becomes small and the "air" connection mode is turned on, just click on one contact pad and then on the other, and such a wonderful green thread will appear between them, which many use to show jumpers on the board, which will then be needed solder. Here are just jumpers, I would not advise her to do it. The fact is that they do not provide a connection during an electrical check. It is best to make jumpers in tracks on the second layer, connecting them through metalized through holes. In this case, an electrical check will show the contact. So, IMHO, joining is a useless thing.

Another useless thing :) However, maybe sometimes it helps to find a path in a tricky place. Yes, she walks on the grid, so if you want it to work better, make the grid smaller.

Control
Electrical control. Finds all closed circuits. An extremely useful thing when wiring. Especially when you already have dofig of all sorts of chains and the eye refuses to perceive this mess. And so he poked the tester - everything lit up. The beauty! It is especially useful to calculate land and nutrition. In order not to forget to power up anything. The main thing is to make jumpers not through the "connection", but along the second layer.

Photovid
In general, it's a cool thing to see how the scarf will look if it is made in production, or you need a more beautiful drawing somewhere to put on a forum or website. And it is also good to look at the solder mask on it, where it is and where it is not. Well, you can admire the silk-screen printing. In general, a useful feature. It also allows you to catch bugs with mirroring letters / components or if something is mistakenly placed on the wrong layer.

In this mode, you can delete or, on the contrary, cover the parts with a mask. Just poking through the wires. There is white - it means open.

Now we come to the small settings.
The first item we have is setting the grid step, the first seven points of the grid step are hammered by the program manufacturer and they cannot be changed in any way, you can only select, but also in the grid settings you can add your own sizes, just click "Add grid step ..." and enter your parameters that I and made by adding mesh spacing 1mm, 0.5mm, 0.25mm, 0.10mm 0.05mm and 0.01mm

The currently active grid step is displayed with a tick and is currently 1 mm

You can also delete the marked grid step or turn it off altogether by clicking on the corresponding line. And if you move with the Ctrl key pressed, the grid step is ignored. Convenient when you need to move something off the grid.

The following three configurable items:

Adjusting the width of the wire, where we adjust the width of our wire.
Setting the size of the pad, here we set the outer and inner diameters.
And the last setting is to adjust the size of the SMD pad horizontally and vertically.

You can also create your own line / area sizes and save them so that you can later select from the list.

Now only the bottom panel is left:

Everything is simple here, on the left we have the position of the cursor and 5 working layers, the active working layer is currently marked with a dot.
Next, we have a button, Plating free areas of the board with metal, this button covers the entire free area of the board with copper and makes gaps around the conductors, here in this windows the value of the required gap is adjusted. It should only be noted that the gap is set for each line separately! Those. it is useless to click this counter. It is necessary to select the entire board (or a specific posting) and only then adjust.

Below it is another icon, a shaded rectangle. It has one interesting property, if you click on it, then we can free the area that we select from the fill on the board.

There really is one subtlety here. The fact is that if we try to connect our fill with wiring, then nothing will come of it. Because the fill will scatter to the sides in panic. The solution is simple - we throw from the ground point to the fill and make a gap for this conductor equal to zero. Everything!

You can also make a negative inscription on the fill. It is also done simply - we put the inscription on the fill (the fill runs away from the inscription in different directions), and then in the properties we put a tick “No gap”. That's it, the inscription has become in the form of slots in the fill.

And I also forgot about such a small hint that appears if you click on a small question.

This is where we finish our first lesson, in it we learned what and where we hide and located what and where is configured.

Part # 2
Let's draw a simple scarf, create a body TQFP-32 and learn how to draw a scarf found on the Internet.

In the last part, we got acquainted with the program, learned what, where, hides, what is configurable and what is not, we learned the little tricks that are in the program.
Now let's try, after reading in the first part, draw a simple board.

As an example, let's take a simple diagram, I dug it up in one of the old magazines, which I won't say, maybe some of the site visitors will remember this magazine.

We see that the old scheme has gone through a lot of things, and edits with a pencil and filling with alcohol-rosin flux, but for our purposes it is ideal because of its simplicity.
Before we draw our scarf, let's analyze the diagram for what we need from the details.

Two microcircuits in DIP packages with 14 legs for each microcircuit.
Six resistors.
One polarized capacitor and two conventional capacitors.
One diode.
One transistor.
Three LEDs.

Let's start drawing our parts, and first, let's decide how our microcircuits look and what sizes they are.

This is how these microcircuits look in DIP packages, and have dimensions between the legs that are 2.54 mm and between the rows of legs these dimensions are 7.62 mm.

Now we will draw these microcircuits and save them as a macro, so as not to draw again in the future and we will have a ready-made macro for future projects.

We launch our program and set the active layer K2, the size of the contact pad is equal to 1.3 mm, its shape is chosen "Rounded vertically", the width of the conductor is equal to 0.5 mm, and the grid spacing is set equal to 2.54 mm.
Now, according to the dimensions that I gave above, we will draw our microcircuit.

Everything worked out as planned.

Then we will save our future board. Click on the floppy disk icon and enter the file name in the field.

We drew the location of the microcircuit legs, but our microcircuit has some kind of unfinished look and looks lonely, we need to give it a more neat look. It is necessary to make a silkscreen outline.

To do this, switch the grid step to 0.3175, set the conductor thickness to 0.1 mm and make the B1 layer active.

With this triangle, we will designate where we will have the first pin of the microcircuit.

Why did I draw this way?
Everything is very simple, in our program, by default, there are five layers: layers K1, B1, K2, B2, U.
The K2 layer is the soldering side (bottom) of the components, the B1 layer is the marking of the components, that is, where to put what or a silkscreen layer that can then be applied to the front side of the board.
The K1 layer is the top side of the board if we make the board double-sided, respectively, the B2 layer is the marking or silkscreen layer for the top side and, accordingly, the U layer is the board outline.

Now our microcircuit looks more neat and tidy.

Why am I doing this? Yes, just because I am depressed by the boards made in some way and in a hurry it happens that you download some thread for a handkerchief from the network, and there are only contact pads and nothing else. We have to check each connection according to the scheme, what came from where, what should go where ...

But I digress. We made our microcircuit in the DIP-14 package, now we need to save it as a macro in order not to draw something like that later, but simply take it from the library and transfer it to the board. By the way, you will hardly find an SL5 without macros, just do it. Some minimal set of standard frames is already in the macros folder. And whole sets of macro assemblies go around the network.

Now hold down the left mouse button and select everything that we just drew.

And all of our three objects will be grouped into one

Here it is the letter M on the microcircuit.
And let's see in the macro window our newly created macro

Excellent, but it would not hurt to decide what size our board will be, I figured out the dimensions of the parts how they can be scattered approximately and counted in the end my size turned out to be 51mm by 26mm.
Switch to layer U - milling layer or board border. At the factory, this contour will be cut by a cutter during manufacture.

Choose a grid step equal to 1 mm

An observant person will say yes, the starting point of the contour does not lie directly at zero and will be absolutely right, for example, when I draw my boards, I always retreat from above and to the left by 1 mm. This is due to the fact that in the future the payment will be made either
using the LUT method or using a photoresist, and in the latter it is necessary that there are negative tracks on the template, that is, white tracks on a dark background, and with this approach in designing the board, it is easier to cut the finished template, make several copies on one sheet. And the board itself looks much more beautiful with this approach. Many probably downloaded the boards from the network and the joke turns out when you open such a board and there, a drawing in the middle of a huge sheet and some kind of pancake crosses around the edges.
Now let's change the grid spacing to 0.635 mm.

And we will put our microcircuits approximately

And put two pads at a distance of 2.54 mm

And on it we will draw the approximate radius of our capacitor, for this we need the arc tool.

So we got our capacitor, we look at the circuit and see that it is connected to pins 4,5 and 1 of the microcircuit, and we'll stick it in there.
Now we set the track width to 0.8 mm and start connecting the legs of the microcircuit, we connect it very simply, first click on one leg of the microcircuit with the left button of the microcircuit, then on the other, and after bringing the conductor (track) to where we wanted to click with the right, after how clicked the right track will no longer continue.

Now, according to a similar principle, we build parts, putting them in our board, we draw conductors between them, we scratch in the back of our head when it is not possible to lay the conductor somewhere, we think, again laying the conductors and in some places do not forget to change the width of the conductor, thus gradually building the board, also when laying conductors, press the space bar on the keyboard, this button changes the bending angles of the conductor, I recommend trying a cool thing. Separately, I want to dwell on the grouping of objects, several objects can be assembled into one by clicking on them with the left button of the bear holding the shift key, and then pressing the grouping. So, we draw, we draw, As a result, we get this:

As a result, the board looks like this:

Now a little explanation on printing a mirrored / non-mirrored image. Usually, the problem arises with LUT, when, due to inexperience, you print an image in the wrong display. The problem is really simple to solve.

In all PCB layout programs, it is accepted that the textolite is "transparent", so we draw tracks as if looking through the board. It's easier this way, in the sense that the numbering of the pins of the microcircuits turns out to be natural, and not mirrored and you don't get confused. So that's it. The bottom layer is already mirrored. We print it as it is.

But the top one needs to be mirrored. So when you make a double-sided (although I do not advise, most of the boards can be separated on one side), then its upper side will need to be mirrored when printing.

Here we have drawn a simple scarf, there are only a few small strokes left.
Reduce the overall size of the working area and print. However, you can just print it as is.

Let's set up several copies, you never know if we suddenly screw it up:

All this, of course, is good, but the scarf itself would not hurt to finish, bring it to mind, and even put it in the archive, suddenly when it comes in handy, or it will be necessary to send it to someone later, but we have not even signed the elements of what and where it costs, in principle it is possible and so we all remember, but here's another person to whom we will give it will be swearing for a long time, checking according to the scheme. Let's make the final touch, put the designations of the elements and their denomination.
First, let's switch to layer B1.

After we have placed all the designations of the elements, we can align them so that it looks more neat, after all these actions, our scarf looks like this:

And in the field we write our value of the resistor R1 according to the scheme, we have it 1.5K
We wrote, click OK and then if we bring the pointer to the resistor R1, then its value will be displayed.

Right-click on the label and select New board in the drop-down menu. Then we answer in the affirmative to the question, open the properties of the new scarf and name it TQFP-32.

Now we open the datasheet on the microcircuit that we are going to draw, for example, looking at the datasheet from ATmega-8.

We look in the datasheet on the microcircuit and see a square with a pancake on each side of the legs, well, it’s okay, just in the top drop-down menu, select another location, namely Four-sided and click on the SMD contact. That's all now, looking into the datasheet, and in this window we look where to enter which parameter, as a result, we fill in all the fields, and we get the following result:

Now we have a very small touch left to zoom in on the image by spinning the mouse wheel away from us, switch to the B2 layer, and draw the outline of the microcircuit and designate where we will have the first leg.

That's all, our case for the TQFP-32 microcircuit has been created, now if something can be printed, attach the microcircuit to a piece of paper, and if a little bit wrong, then slightly correct the parameters, and then save it as a macro so as not to draw a similar case in the future.

Drawing a picture
And the last step of our lesson, I will tell you how to make a scarf from an image of a board found in a magazine or on the Internet.

To do this, create the next tab and name it Internet.
In order not to search for a long time, we will go out to the Internet and in the search engine we will type "Printed circuit board", the search engine will throw out a bunch of links and pictures, we will choose something from them just like that.

After we have drawn, take our image and, using a graphical editor, remove everything that we have on the left side, in principle we do not need it, but we will save the right side to a file with the .mp extension. If we scan a scarf from a magazine, then it is better to scan with a resolution of 600 dip and save it to a file.VMP After saving it in the program, go to the K2 layer, click on the TEMPLATE icon.

Click the Load ... button and select our file. After that, the screen will look like this

That's all, now we just outline this picture with details. It is quite possible that the details may not fall from 100% to the one drawn in the picture, this is not scary, the main thing is there is a picture on the background layer and a set of macros with a fixed size and this is the most important thing. Sprint-Layout has a great set of macros, and gradually, when new details are drawn, it will also be replenished with its own.

If you click on the top, then while we hold it, our tracks will become invisible, and if on the bottom, then while we hold it, our picture will become invisible, which was superimposed by the background.

That's basically all about the Sprint-Layout program, I think for beginners to master it, there is plenty of information, and of course you need to remember everything what and where to click, how and what to do. And at the end of the lesson about the Sprint-Layout program, you can download the file itself with these boards, on which the mastering of this program took place.

Happy circuit board creation!

Multimedia amplifier based on TDA1554 2.1

This amplifier is designed to create a 2.1 system, i.e. 2 broadband amplifiers + 1 more powerful, designed to reproduce only low frequency signals.
The schematic diagram of the amplifier is shown in Figure 1, the drawing of the printed circuit board is shown in Figure 2 (not to scale). You can take a drawing in lay format.

Picture 1.

Figure 2. DOWNLOAD THE BOARD IN LAY

PCB FOR HIGH QUALITY POWER AMPLIFIER

This multimedia amplifier is designed to create a mid-range audio system designed for stationary use.
The amplifier is based on the popular TDA2030 microcircuits and the not very popular TDA2052. Well, since we are talking about these microcircuits, it is better to dwell in more detail on each of them.
According to the reference book, the TDA2030 belongs to the category of Hi-Fi amplifiers, but this is said to be too loud - its sound is somewhat non-Hi-Fi. Its more powerful brother, the TDA2050, sounds much nicer. In terms of pinout, it completely coincides with the TDA2030, so you can replace it without changing almost anything on the PCB.
The schematic diagram of the amplifier on the TDA2030 microcircuit is shown in Figure 1, in Figure 2 - TDA2050 - drawing and imported from the datasheet. The only thing that has been changed in the circuit is that there are no diodes from the m / s output to plus or minus power supply. These diodes are used to reduce the self-induction of the dynamic head, and few people will decide to use this circuit with heads with a "heavy" diffuser, then the diodes were simply excluded from the circuit. A large batch of boards produced without these diodes showed that the amplifier works as stably as with them, i.e. the operation of the scheme was not influenced.

Picture 1.

Figure 2.

Of course, the ratings in the OOS circuit are different, but their ratio is almost the same, which means coffee. they have the same gain. In addition, the TDA2050 OOS option is more preferable, since more current flows through smaller resistors, therefore, it is less critical to pickups and external interference. And yet - we allowed ourselves to bypass R5 with a series-connected 100 kΩ resistor and a 100 pF capacitor. This increases the stability of the amplifier and ensures that the box rolls off. amplification at frequencies above 20 kHz.
The power supply of the amplifier is chosen unipolar since there is almost no deterioration in sound quality, but this fact opens additional horizons:
- there is some savings in electrolytic capacitors for power supply;
- when creating a multimedia amplifier using a bipolar power supply, the positive "branch" of the power supply is used to power the midrange-HF link as an amplifier with a unipolar power supply, and the positive and negative "branches" are used as the power supply of the amplifier for the subwoofer. Thus, the amplifier circuitry is rather not badly simplified.
If there is no desire to bother with a bipolar, then you can use a bridge connection of microcircuits, just give a correction for the fact that in a bridge connection much more power is required from m / s. For example, when using the MF-HF link with the TDA2030, the bridge amplifier should be used with the TDA2050, but if the MF-HF amplifiers are based on the TDA2050 chip, then the bridge amplifier must already be taken on the basis of the TDA2052.
Figure 3 shows a sketch of a printed circuit board for one TDA2030.

Figure 3. DOWNLOAD IN LAY

Well, a few words about the amplifier on the TDA2052 microcircuit. This is an integrated power amplifier that allows you to develop at a load of 4 ohms up to 40 watts. The schematic diagram of the amplifier is shown in Figure 4.

Figure 4.

This is an amplifier with two inputs, but to simplify the design, the second input is simply not used. A sketch of the printed circuit board is shown in Figure 5. Figure 6 is a sketch of the TDA2052 bridge connection, but in Figure 7, a sketch of the printed circuit board of the TDA2030 (TDA2050) multimedia amplifier itself and the TDA2052 bridge amplifier.
The drawing of the printed circuit board of the power amplifier is one for all - DOWNLOAD.

Figure 5.

Figure 6.

Figure 7.

Integrated four-channel power amplifiers.

How to quickly assemble an amplifier for 4 channels, and at the same time they are not afraid to repair automotive equipment will be told here ...

We are talking about a number of microcircuits that have one switching circuit, but different characteristics. Of course, they also have one signet. Well, let's start in order:
In automotive technology, the TDA7381, TDA7382, TDA7383, TDA7384, TDA7385, TDA7386 microcircuits are often used, somewhat less often TDA7560. All these monsters practically have one switching circuit, shown in Figure 1, but their characteristics differ somewhat, which is actually reflected in Table 1.

Picture 1.

TABLE 1.

PARAMETER	PARAMETER FOR MICROCIRCUIT
PARAMETER
Type of shell	FLEXIWATT25
Gain cof, dB
Supply voltage, V
Output power at THD 10%		25 45
Output power at THD 1%		19 34
Maximum output power (a rectangular signal with an amplitude of 100 mV is fed to the input), this is what is written on the "muzzles" of the radio tape recorders.		50 80
THD,%, at P = 4W
Input impedance, kOhm
Diagnostics, pin 25 is enabled.
Voltage at the control inputs MUTE and St-By for switching on in the operating mode, not less, V

Blue indicates the parameters for a load of 2 Ohm, please note that only TDA7560 can work with 2 Ohms (!)
One nuance is indicated in pink - these microcircuits have a diagnostic output, which is fed to the central processor and if it is used in the radio tape recorder, then the microcircuit can only be replaced with a diagnostic output, otherwise the CPU simply will not give permission for the volume and tone control, and some may even will not turn on ... Well, for the manufacture of a separate amplifier, this does not matter.

Well, what kind of mikruhi they sort of figured out, now the printed circuit boards for this four-channel:

Figure 2.

Figure 2 shows a sketch of a printed circuit board, a drawing in lay format, in jpg, in jpg the drawing is already expanded, i.e. prepared for laser iron. J1 jumper is spaced in height, I just didn't want to drag ultra-thin tracks between the pins, and it's not serious to make a double-sided board for such a primitive either ... You can read a little more about TDA7384 and TDA7560.
The microcircuits are heated quite well, and at least the operating temperature is more than 100 degrees. Intact. it is better not to skimp on a radiator.

And finally, a couple of words about the miracle that I was able to see, namely the very original use of the amplifier on the TDA7560 in the car. 4 loudspeakers 25GDN are installed in an absolutely flat case, the height of which is about 170 mm. Length and width are tailored to the size of the classic trunk. Bass reflex is installed. The speakers are connected in parallel in pairs, i.e. load 2 Ohms and connected to the two outputs of the TDA7560. The remaining pair of outputs are connected to paired JBLs with a diameter of 160mm, i.e. another stereo set of 2 ohms installed in the rear shelf. Front acoustics from JVC head.
I really liked the train of thought of this needleman - there is no pipe of unmeasured dimensions lying around the trunk, there is about 200 real watts and this is without any converters ... True, the radiator of the mirkruha with some kind of stationary amplifier looks like Lortovsky, only it seems like it is higher ...

PCB FOR MULTIMEDIA AMPLIFIER ON TDA1554 & TDA1562

This multimedia amplifier is designed to create a mediocre audio system and can be used both in a car and in a hospital.
The main disadvantage of the system is the somewhat underestimated value of the boost capacitors, although the schematic diagrams of both amplifiers are taken from the datasheet - Figures 1 and 2.

Picture 1.

Figure 2.

In reality, the low frequency sound becomes much better when using C1 and C2 at 10000mkF, but they did not bring the board to the "mind" ...
By the way, nothing gets in the way, having slightly corrected the board, make a separate amplifier on the TDA1554 or TDA1562.
Figure 3 shows a drawing of the board (not to scale), the same in lay format.

Figure 3.

You can see the details of how much power a power supply is needed for a power amplifier in the video below. The STONECOLD amplifier is taken as an example, but this measurement gives an understanding that the power of the mains transformer can be less than the power of the amplifier by about 30%.

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Updated: 27.04.2016

An excellent amplifier for the home can be assembled on the TDA7294 chip. If you are not strong in electronics, then such an amplifier is ideal, it does not require fine tuning and debugging like a transistor amplifier and is easy to build, unlike a tube amplifier.

The TDA7294 microcircuit has been produced for over 20 years and still has not lost its relevance, and is still in demand among radio amateurs. For a novice radio amateur, this article will be a good help to get acquainted with integrated audio frequency amplifiers.

In this article I will try to describe in detail the amplifier device on the TDA7294. I will focus on a stereo amplifier assembled according to the usual scheme (1 microcircuit per channel) and briefly tell you about the bridge circuit (2 microcircuits per channel).

Chip TDA7294 and its features

TDA7294 - the brainchild of SGS-THOMSON Microelectronics, this microcircuit is an AB class low frequency amplifier, and is built on field-effect transistors.

Of the advantages of the TDA7294, the following can be noted:

output power, with distortion of 0.3-0.8%:
- 70 W for 4 ohm load, conventional;
- 120W for 8 ohm load, bridged;
Mute function and Stand-By function;
low noise level, low distortion, frequency range 20-20000 Hz, wide operating voltage range - ± 10-40 V.

Specifications

Technical characteristics of the TDA7294 microcircuit
Parameter	Conditions	Minimum	Typical	Maximum	Units
Supply voltage		± 10		± 40	V
Frequency Response Range	Signal 3 db Output power 1W	20-20000			Hz
Long Term Output Power (RMS)	harmonic coefficient 0.5%: Uп = ± 35 V, Rн = 8 Ohm Uп = ± 31 V, Rн = 6 Ohm Uп = ± 27 V, Rн = 4 Ohm	60 60 60	70 70 70		W
Peak music output power (RMS), duration 1 sec.	harmonic coefficient 10%: Uп = ± 38 V, Rн = 8 Ohm Uп = ± 33 V, Rн = 6 Ohm Uп = ± 29 V, Rн = 4 Ohm		100 100 100		W
Total harmonic distortion	Po = 5W; 1kHz Po = 0.1-50W; 20-20000Hz		0,005	0,1	%
Total harmonic distortion	Uп = ± 27 V, Rн = 4 Ohms: Po = 5W; 1kHz Po = 0.1-50W; 20-20000Hz		0,01	0,1	%
Protection response temperature		145			° C
Quiescent current		20	30	60	mA
Input impedance		100			kOhm
Voltage gain		24	30	40	dB
Peak output current		10			A
Working temperature range		0		70	° C
Thermal resistance of the case				1,5	° C / W

Pin assignment

Pin assignment of the TDA7294 microcircuit
Chip pin	Designation	Appointment	Connection
1	Stby-GND	"Signal ground"	"General"
2	In-	Inverting input	Feedback
3	In +	Non-inverting input	Audio signal input via coupling capacitor
4	In + Mute	"Signal ground"	"General"
5	N.C.	Not used	–
6	Bootstrap	"Voltodopavka"	Capacitor
7	+ Vs	Input stage power supply (+)
8	-Vs	Input stage power supply (-)
9	Stby	Standby mode	Control block
10	Mute	Mute mode	Control block
11	N.C.	Not used	–
12	N.C.	Not used	–
13	+ PwVs	Output stage power supply (+)	Positive terminal (+) of the power supply
14	Out	Output	Audio signal output
15	-PwVs	Output stage supply (-)	Minus terminal (-) of the power supply

Note. The microcircuit case is connected to the minus power supply (pins 8 and 15). Do not forget about isolating the heatsink from the amplifier case or isolating the microcircuit from the heatsink by installing it through a thermal pad.

I also want to note that in my scheme (as in the datasheet) there is no separation of input and output "lands". Therefore, in the description and on the diagram of the definition of "common", "ground", "body", GND should be taken as concepts of the same sense.

Difference in housings

The TDA7294 microcircuit is available in two types - V (vertical) and HS (horizontal). TDA7294V, having a classic vertical design of the case, was the first to leave the assembly line and is still the most common and affordable.

Complex of protection

The TDA7294 chip has a number of protections:

protection against power surges;
protection of the output stage against short circuit or overload;
thermal protection. When the microcircuit is heated to 145 ° C, the Mute mode is activated, and at 150 ° C, the Stand-By mode is activated;
protection of the microcircuit terminals from electrostatic discharges.

Power amplifier on TDA7294

A minimum of parts in the harness, a simple printed circuit board, patience and known good parts will allow you to easily assemble an inexpensive UMZCH on the TDA7294 with clear sound and good power for home use.

You can connect this amplifier directly to the line-out jack of your computer's sound card. the nominal input voltage of the amplifier is 700 mV. And the level of the nominal voltage of the line output of the sound card is regulated within 0.7-2 V.

Block diagram of the amplifier

The diagram shows a variant of a stereo amplifier. The structure of the bridge amplifier is similar - there are also two boards with TDA7294.

A0... Power Supply
A1... Control unit for Mute and Stand-By modes
A2... UMZCH (left channel)
A3... UMZCH (right channel)

Pay attention to the connection of the blocks. Improper wiring inside the amplifier can cause additional noise. To minimize noise as much as possible, follow a few rules:

Power to each amplifier board must be supplied with a separate harness.
The power wires must be twisted into a pigtail (harness). This will compensate for the magnetic fields created by the current flowing through the conductors. We take three wires ("+", "-", "General") and weave a pigtail from them with a slight interference.
Avoid earth loops. This is a situation when the common conductor, connecting the blocks, forms a closed loop (loop). The connection of the common wire must go in series from the input connectors to the volume control, from it to the UMZCH board and further to the output connectors. It is advisable to use connectors isolated from the case. And for the input circuits also shielded wires with insulation.

List of parts for PSU TDA7294:

When purchasing a transformer, note that the effective voltage value is written on it - U D, and by measuring with a voltmeter you will also see the effective value. At the output after the rectifier bridge, the capacitors are charged to the amplitude voltage - U A. The amplitude and effective voltages are related by the following relationship:

U A = 1.41 × U D

According to the characteristics of the TDA7294 for a load with a resistance of 4 ohms, the optimal supply voltage is ± 27 volts (U A). The output power at this voltage will be 70 W. This is the optimal power for the TDA7294 - the distortion level will be 0.3–0.8%. There is no point in increasing the power supply to increase the power. the level of distortion is growing like an avalanche (see graph).

We calculate the required voltage of each secondary winding of the transformer:

U D = 27 ÷ 1.41 ≈ 19 V

I have a transformer with two secondary windings, with a voltage of 20 volts on each winding. Therefore, in the diagram, I marked the power terminals as ± 28 V.

To obtain 70 W per channel, taking into account the efficiency of the microcircuit of 66%, we consider the power of the transformer:

P = 70 ÷ 0.66 ≈ 106 VA

Accordingly, for two TDA7294s, this is 212 VA. The nearest standard transformer, with a margin, will be 250 VA.

It is appropriate to state here that the power of the transformer is calculated for a pure sine wave signal; corrections are possible for a real musical sound. So, Igor Rogov claims that for a 50 W amplifier, a 60 VA transformer will be enough.

The high-voltage part of the PSU (up to the transformer) is assembled on a 35 × 20 mm printed circuit board;

The low-voltage part (A0 according to the structural diagram) is assembled on a 115 × 45 mm printed circuit board:

All amplifier boards are available in one.

This power supply unit for TDA7294 is designed for two microcircuits. For more microcircuits, it will be necessary to replace the diode bridge and increase the capacitance of the capacitors, which will entail a change in the dimensions of the board.

Control unit for Mute and Stand-By modes

The TDA7294 microcircuit has Stand-By and Mute modes. These functions are controlled through pins 9 and 10, respectively. The modes will be turned on as long as there is no voltage at these pins or it is less than +1.5 V. To "wake up" the microcircuit, it is enough to apply a voltage greater than +3.5 V to pins 9 and 10.

For the simultaneous control of all UMZCH boards (especially important for bridge circuits) and saving radio components, there is a reason to assemble a separate control unit (A1 according to the structural diagram):

Parts list for control box:

Diode (VD1)... 1N4001 or similar.
Capacitors (C1, C2)... Polar electrolytic, domestic K50-35 or imported, 47 μF 25 V.
Resistors (R1 – R4)... Normal low-power.

The block's printed circuit board has dimensions of 35 × 32 mm:

The task of the control unit is to provide silent switching on and off of the amplifier due to the Stand-By and Mute modes.

The principle of operation is as follows. When you turn on the amplifier, together with the capacitors of the power supply, the capacitor C2 of the control unit is also charged. As soon as it is charged, the Stand-By mode will turn off. The capacitor C1 takes a little longer to charge, so the Mute mode will turn off in the second turn.

When the amplifier is disconnected from the mains, the capacitor C1 is discharged first through the VD1 diode and turns on the Mute mode. Then the capacitor C2 discharges and sets the Stand-By mode. The microcircuit becomes silent when the capacitors of the power supply have a charge of about 12 volts, so no clicks and other sounds are heard.

Amplifier on TDA7294 in the usual way

The circuit for switching on the microcircuit is non-inverting, the concept corresponds to the original from the datasheet, only the ratings of the components have been changed to improve the sound characteristics.

Parts List:

Capacitors:
- C1... Film, 0.33-1 μF.
- C2, C3... Electrolytic, 100-470 μF 50 V.
- C4, C5... Film, 0.68 μF 63 V.
- C6, C7... Electrolytic, 1000 μF 50 V.
Resistors:
- R1... Variable double with linear characteristic.
- R2 – R4... Normal low-power.

Resistor R1 is double because amplifier stereo. Resistance no more than 50 kOhm with linear, not logarithmic characteristic for smooth volume control.

The R2C1 circuit is a high-pass filter (HPF), suppresses frequencies below 7 Hz, without passing them to the amplifier input. Resistors R2 and R4 must be equal to ensure stable operation of the amplifier.

Resistors R3 and R4 organize a negative feedback circuit (OOS) and set the gain:

Ku = R4 ÷ R3 = 22 ÷ 0.68 ≈ 32 dB

According to the datasheet, the gain should be within 24-40 dB. If less, then the microcircuit will self-excite, if more, distortion will grow.

Capacitor C2 participates in the OOS circuit, it is better to take with a larger capacity in order to reduce its effect on low frequencies. Capacitor C3 provides an increase in the supply voltage of the output stages of the microcircuit - "voltage boost". Capacitors C4, C5 eliminate wire induced noise, and C6, C7 complement the filter capacity of the power supply. All amplifier capacitors, except C1, must have a voltage margin, so we take at 50 V.

The printed circuit board of the amplifier is one-sided, rather compact - 55 × 70 mm. When developing it, the goal was to dilute the "earth" with a star, to ensure versatility and at the same time keep the minimum dimensions. I think this is one of the smallest boards for the TDA7294. This board is designed for the installation of one microcircuit. For the stereo version, respectively, two boards are required. They can be installed side by side or one above the other like mine. I'll tell you more about versatility a little later.

The radiator, as you can see, is indicated on one board, and the second, similar, is attached to it from above. Photos will be a little further.

Amplifier on the TDA7294 bridge circuit

The bridge circuit is a pairing of two conventional amplifiers with some amendments. Such a circuit solution is designed to connect acoustics with an impedance of not 4, but 8 ohms! The acoustics are connected between the outputs of the amplifiers.

There are only two differences from the usual scheme:

the input capacitor C1 of the second amplifier is connected to ground;
added feedback resistor (R5).

The printed circuit board is also a combination of amplifiers in the usual way. Board size - 110 × 70 mm.

Universal board for TDA7294

As you may have noticed, the aforementioned boards are essentially the same. The next PCB option fully confirms the versatility. This board can be used to assemble a 2 × 70 W stereo amplifier (conventional circuit) or a 1 × 120 W mono amplifier (bridged). The board size is 110 × 70 mm.

Note. To use this board in a bridged version, you must install the resistor R5, and set the jumper S1 in the horizontal position. In the figure, these elements are shown with a dotted line.

For a conventional circuit, the resistor R5 is not needed, and the jumper must be installed vertically.

Assembly and commissioning

Assembling the amplifier is straightforward. As such, the amplifier does not require adjustment and will work immediately, provided that everything is assembled correctly and the microcircuit is not defective.

Before using for the first time:

Make sure the radio components are installed correctly.
Check that the power wires are connected correctly, do not forget that on my amplifier board, the "ground" is not in the center between the plus and minus, but on the edge.
Make sure that the microcircuits are isolated from the heatsink, if not, check that the heatsink does not contact ground.
Apply power to each amplifier in turn, so there is a chance not to burn all the TDA7294s at once.

First turn on:

We do not connect the load (acoustics).
We short-circuit the inputs of the amplifiers to ground (short-circuit X1 with X2 on the amplifier board).
We serve food. If everything is fine with the fuses in the power supply unit and nothing smokes, then the launch was successful.
Using a multimeter, we check the absence of direct and alternating voltage at the output of the amplifier. A slight constant voltage is allowed, no more than ± 0.05 volts.
We turn off the power and check the case of the microcircuit for heating. Be careful, the capacitors in the power supply take a long time to discharge.
We give a sound signal through a variable resistor (R1 according to the scheme). We turn on the amplifier. The sound should appear with a short delay, and immediately disappear when turned off, this characterizes the operation of the control unit (A1).

Conclusion

I hope this article will help you build a quality amplifier based on the TDA7294. Finally, I present several photos during the assembly process, do not pay attention to the quality of the board, the old PCB was etched unevenly. As a result of the assembly, some edits were made, so the boards in the .lay file differ slightly from the boards in the photographs.

The amplifier was made for a good friend, he invented and implemented such an original case. Photos of the TDA7294 stereo amplifier assembly:

On a note: All printed circuit boards are collected in one file. To switch between "seals", click on the tabs as shown in the figure.

list of files

We all love to assemble circuits, but not everyone wants and knows how to lay printed circuit boards. Most often we look for a ready-made seal on the Internet and in most cases we find it. It would seem, go ahead, etch and solder! But not everything is so rosy, because often these found seals look like this:

Not a single signed item. Complete rebus, riddle! And, like, turn on the "mosch" and stuff the elements, because the diagram is at hand. But the program was created to make life easier for us, and not vice versa.

Therefore, I will briefly, from the very beginning, tell you how to approach the layout of the board in Sprint-Layout, so that you don't have to guess later what kind of detail I put in here. Let's get it right right away!

You cannot cover everything in one small article, I will go through some of the main points. So, we create a new project, set the name of the board and the estimated size (it can be easily adjusted later).

Don't forget to choose a suitable work mesh.

For small projects with large elements, a mesh of 1.27 mm is suitable, for more advanced and dense 0.635 mm, and so on. Elements and tracks will be placed with reference to the nodes of this grid. You can make a grid for Soviet parts: 2.5 mm or 1 mm.

Be sure to understand the layer system in the program, understand how everything works, use the photo view.

Make labels on layers for labels, and tracks and polygons on layers for copper, etc.
The archive contains help programs in Russian.

We start adding details to the board. At this stage, the values of "Type" and "Denomination" should not be confused, later I will tell you why.

Enter the values, adjust the font size to taste, click OK.

We see the element with the marking. Now we can distribute and "seal" our markings.
We select the denomination and drag it with the mouse to the desired place. Before that, you need to reduce the size of the grid to an acceptable level.

That's better.

Now move the element designation closer. If necessary, you can rotate it by selecting it before.

Further, so as not to suffer so much with each element, we simply copy it and change the data in the element's properties.

Our board is already quite ready to manufacture, but why do we need to overload the solution with excess copper?
There is no need! We will minimize the area of copper to be vented. To do this, select all the elements on the board and press the "Metallization" button at the bottom of the program window and change the value to an acceptable one, for example 0.5 mm.

Everything is fine, but some legs can and sometimes even need to be placed on a metallized area. There is nothing difficult.

Select the required legs and change the metallization offset value to 0. That's it, now the leg is on the earth bus.

And if you need a thermal barrier to facilitate soldering on large polygons? Select the path drawing and draw the thermal barrier.

This is the simplest and most obvious way. But you can also use the built-in capabilities of the program to create thermal barriers. Highlight the pad you want and study the menu on the right.

Check the "Thermal barrier" checkbox and adjust the direction and width of the "bridges" of the barrier. It is very convenient that many sites can be configured at once. The thermal barrier function works only on the switched on automatic landfill. Not supported by all versions of Sprint-Layout. Use fresh.

Everything is drawn, we can admire the result by pressing the "photoview" button.

A nuance - you can edit the size of the labels of the elements separately, for this, select the "victim" and press the properties button on the right. The settings are pretty extensive. However, it is best to set all decals in the same style.

It was the turn of the "cosmetics". So that all the drawings of the elements on the board have a uniform appearance and line thickness, do the following:
1.select the layer with the marking of the elements;
2. turn off the track layer;
3. select everything (ctrl + A);
4. adjust the thickness of the lines of all elements at the same time;
5. Activate the tracks layer again.

The beauty! By the way, do not forget to adjust the colors of the layers in the program to all taste, to whom my palette seemed gloomy.

Now let us recall the beginning of the article and find out why you should not enter the nominal value of an element in the field for its type. It's simple, it turns out that when we add elements, we have already formed a list of elements!

Of course, the more correct practice is the primacy of the circuit in the project, then the creation of the list of elements is the business of the program for drawing the circuits. In the set of programs from ABACOM it is sPLAN.
Editorial note

It remains only to buy according to the list and get a beautiful home-made board as a result. And people are not ashamed to show such a drawing on the forum, and there will be no unnecessary questions about the board.

Files

And here is the Russian help for Sprint-Layout and an excellent free book by our comrade Mikhail Tsarev (Tsoy73):
▼ 🕗 27/12/16 ⚖️ 2.14 Mb ⇣ 168 Many are familiar with wiring and PCB technology such as. But what to do when the diagram is too complex and voluminous? Here you will have to master more modern methods, with one of which we will get acquainted here. Take, for example, the schematic of this sound probe:

Device diagram

It makes no significant difference whether we will lay the board on a piece of paper in a cage by cutting out templates of parts with leads from cardboard (although I deeply doubt that anyone will use this method in the 21st century, when every house has a computer), or we will use some kind of PCB layout program, such as sprint layout. Of course, using sprint layout will make it much easier, especially in large layouts. In both cases, first we put on the working field the part with the largest number of leads in our case it is a transistor, for example VT1, this is KT315 for us. (A link to the sprint layout manual will be provided below). And at first, when designing, your printed circuit board may resemble a schematic diagram, it's okay, I think everyone started that way. We put it, then we connect its base and emitter with tracks to the resistor R1, we also have the base VT1 connected to the output of the capacitor C1 and the output of the resistor R2. Instead of lines on the diagram, we connect the pins of the parts with a track on the printed circuit board. I also made it a rule to count the number of pins of parts connected on the circuit and on the printed circuit board, we should get the same number of connected spots.

As you can see, 3 more pins are connected to the base on our board as well as on the diagram, on the diagram they are marked with red rings. Next, we install the transistor VT2 - this is a kt361 transistor, it is a pnp structure, but we do not care at the moment, since it also has 3 terminals and in a package exactly the same as kt315. We installed the transistor, then we connect its emitter with the second terminal R2, and the second terminal of the capacitor C1 with the collector VT2. We connect the VT2 base to the VT1 collector, install the pins on the board for connecting the BA1 speaker, we connect it with one pin to the VT2 collector, the other pin to the VT1 emitter. Here's how everything that I described looks like on the board:

We continue further, we install the LED, connect it to the BA1 pin and to the VT2 emitter. After we install the transistor VT3, this is also kt315 and connect it with a collector to the cathode of the LED, we connect the emitter VT3 to the minus of the power supply. Next, we install the resistor R4 and connect it with tracks to the base and emitter of the transistor VT3, we put the output from the base on the X1 probe. Let's see what happened on the board:

Finally, we install the last few details. Install the power switch, connecting it to the power supply plus a track from one patch and with the emitter VT2, a path from another patch connected to the switch. We connect this output of the switch with the resistor R3, and connect the second patch of the resistor to the contacts of the X2 probe.

Everything, the board is divorced ... If you really want to, you can transfer this drawing to a textolite, etch this board and you will have a Sound Probe device with a continuity of resistance up to 650 Ohm. Of course, it was possible, if desired, to part more compactly, but I did not have such a goal, my goal was to tell in stages about the process of creating a PCB layout. If someone is interested in the process of creating boards using the program sprint layout, I recommend to go through and read the manual