Car amplifier - economical options for creating sound in the cabin. DIY amplifier: master class on building a simple and effective device for signal amplification

Factory-made devices for amplifying the audio signal are expensive and may not be powerful enough. Looking at photos of homemade sound amplifiers, it is obvious that they are in no way inferior in appearance to finished products. In addition, their manufacture on their own does not require special skills or large material costs.

Device base

Beginner radio amateurs first of all ask themselves: what can they use to assemble a simple sound amplifier at home? The operation of the device is based on transistors or microcircuits, or a rare option is possible - on lamps. Let's take a closer look at each of them.

Microcircuits

The TDA series microcircuit and a similar one can be purchased in stores or you can use a microcircuit from an unnecessary TV.

Using car amplifier chips with a 12-volt power supply, it is very easy to achieve high-quality sound without the use of special skills and with a minimum of parts.

Transistors

The advantages of transistors are low power consumption. The device produces excellent sound performance, is easily integrated into any equipment and does not require additional configuration. In addition, there is no need to search for and use complex microcircuits.

Lamps

Today, the outdated assembly method based on tubes provides high-quality sound, but has a number of disadvantages:

• increased energy intensity
• dimensions
• cost of components

Recommendations for properly assembling a sound amplifier with your own hands

A device for enhancing sound quality, assembled at home based on TDA series microcircuits and their analogues, generates a lot of heat. For cooling, you need a radiator grille of a suitable size, depending on the model of the microcircuit itself and the power of the amplifier. There must be a place for it in the case.

The advantage of a self-made device is its low energy consumption, which allows it to be used in cars by connecting to a battery, as well as on the road or at home using a battery. Power consumption depends on the required degree of signal amplification. Some manufactured models require a voltage of only 3 Volts.

We take a serious and responsible approach to assembling a sound amplifier in order to avoid short circuits and failure of components.

Necessary materials

During the assembly process you will need the following tools and components:

• chip
• frame
• capacitors
• power unit
• plug
• switch button
• wires
• cooling radiator
• screws
• hot glue and thermal paste
• soldering iron and rosin

Circuits and instructions for making an amplifier at home

Each circuit is unique and depends on the sound source (old or modern digital technology), power supply, and expected final dimensions. It is assembled on a printed circuit board, which will make the device compact and more convenient. During the assembly process, you cannot do without a soldering iron or soldering station.

The British John Linsley-Hood circuit is based on four transistors without microcircuits. It allows you to similarly repeat the shape of the input signal, resulting in only pure gain and a sine wave at the output.

The simplest and most common option for manufacturing a single-channel amplifier is to use a microcircuit based on it, supplemented with resistors and capacitors.

Algorithm of actions for production

• install on printed circuit board radio components, taking into account polarity
• assemble the body (providing space for additional parts, for example, a radiator grille)

It is permissible to use a ready-made case or create it yourself, as well as install the board into the speaker case.

• run the device in test mode (identify and eliminate malfunctions if they occur)
• amplifier assembly (connection to the power supply and other components)

Note!

DIY home and car amplifiers

At home, there is often a lack of powerful sound when watching movies on a laptop or listening to music on headphones. Let's look at how to properly make a sound amplifier with your own hands.

For laptop

The sound wave amplifier must take into account the power of external speakers up to 2 watts and winding resistance up to 4 ohms.

Assembly components:

• 9 volt power supply
• printed circuit board
• chip TDA 7231
• frame
• non-polar capacitor 0.1 µF - 2 pcs.
• polar capacitor 100 µF
• polar capacitor 220 µF
• polar capacitor 470 µF
• constant resistor 10 Kom m 4.7 Ohm
• two-position switch
• input socket

Manufacturing scheme

The assembly algorithm is selected depending on the selected scheme. It is necessary to consider the appropriate size of the cooling radiator so that the operating temperature inside the case does not rise above 50 degrees Celsius. When using a laptop outdoors, you need to provide holes in the case for air access.

For car radio

An amplifier for a car radio can be assembled using the common TDA8569Q microcircuit. Its characteristics:

• supply voltage 6-18 volts
• input power 25 watts per channel into 4 ohms and 40 watts per channel into 2 ohms
• frequency range 20-20000 Hz

Note!

It is imperative to provide an anti-interference filter in addition to the circuit, created by work car.

First, draw a printed circuit board, then drill holes in it. Then the board must be etched with ferric chloride. After tinning and soldering all the parts of the microcircuit. To avoid power additives, a thick layer of solder will need to be applied to the power traces. Provide a cooling system using a cooler or radiator grille.

At the end of the assembly, it is necessary to make a filter against interference from the ignition system and poor noise insulation according to the following scheme: on a ferrite ring with a diameter of 20 mm, wind a choke with a wire with a cross-section of 1-1.5 mm in 5 turns.

Assembling a device to improve sound quality at home is not difficult. The main thing is to decide on the circuit and have on hand all the components from which you can easily assemble a simple sound amplifier.

DIY sound amplifier photo

Note!

Many people are interested in how to make portable speakers or speakers for smartphones and tablets. However, before you start making the speakers themselves, you need to take care of the amplifier. In this material we will review a video about assembling a simple amplifier.

So, what do we need to assemble the amplifier:
- connector for crown;
- 9 volt crown;
- speaker 0.5-1 W and resistance 8 Ohms;
- 3.5 mm mini jack;
- 10 Ohm resistor;
- switch;
- microcircuit LM386;
- 10 volt capacitor.

So that the assembly process does not seem very complicated, we present to your attention a diagram of the future amplifier.

Looking at the chip from a closer distance, you can see that it has four tabs on both sides. In total there are 8 legs. In order not to confuse or turn the microcircuit upside down and thereby make a mistake with soldering, a small mark similar to a semicircle is provided on the microcircuit. This mark should be located at the top.

Let's start by soldering the first wire, which will go to the switch and the positive contact of the crown. This wiring must be soldered to the sixth leg of the microcircuit, that is, the second from the bottom on the right side.

The next end of the wire must be soldered to the switch. It is worth noting here that, according to the author of the idea, the circuit itself does not present any difficulty and even someone who does not have special skills in electronics can handle the assembly.

After successfully soldering the first wire, you need to move to the second contact of the switch, which is on this moment free Here you need to solder the positive wire coming from the crown connector. After such simple soldering, we can say that the first stage of amplifier manufacturing has been successfully completed.

Let's move on to the next foot, which is marked with the number 5 in the diagram and is located directly under the sixth foot, that is, the one to which we soldered the wire at the previous stage of work. You need to solder the positive contact of the capacitor to this paw.

From the capacitor we are left with a negative contact, which must be soldered to the positive contact of the speaker. If you wish, you can refuse to directly solder the capacitor to the speaker in order to protect it from possible damage, as the author does. In this case, you need to shorten the contact of the capacitor and lengthen it with wiring.

After this, you can solder wires from the minus of the capacitor to the plus of the speaker.

The negative contact of the speaker must be soldered to the fourth and second legs on the chip. Accordingly, these are the lower and second paws from the top on the left side. To do this, take the wiring and solder it to the negative of the speaker.

After this, we connect this wire to the fourth leg of the microcircuit.

To connect the same wire to the second leg, you need to make a jumper. We take a short wire. We solder one end to the fourth leg, which already has one wire, and the other end to the second leg.

We must solder a resistor to the third leg on the left side, that is, the one located between the previous two.

We solder a wire to the second leg of the resistor that will go to the positive contact on the mini jack.

Let's disassemble the mini-jack. The mini jack that the author uses has two contacts - for the left and right channels. They need to be connected to each other and solder the wire going from the resistor to the contacts.

How to achieve high-quality sound of your favorite music? Arm yourself with the necessary knowledge and tools, after which you can assemble a sound amplifier with your own hands.

Which amplifier is better?

There are as many opinions as there are radio amateurs. Basically, the choice depends on the person, so it is very difficult to draw any specific conclusions. Today you can assemble a sound amplifier with your own hands using:

• Transistors. They have low power consumption and compact size. They provide excellent sound quality.
• Lampah. An old fashioned way of assembling radio equipment. Despite its monstrous gluttony, weight and size, it surpasses semiconductor analogues in sound quality.

Where to begin?

Before making a sound amplifier, you need to clearly understand under what conditions and for what purpose it will be used. This directly determines how much power it should have. In order to listen to your favorite songs at home, a small device that will provide high-quality sound with a power of 30 - 50 W is enough. The situation will be completely different if you need to create equipment for large-scale events. In this case, it becomes necessary to assemble a more complex sound amplifier with your own hands. 200W is far from the limit of power that will be needed during operation.

You should also stock up on everything you need:

• Soldering iron.
• Multimeter.
• Screwdriver Set.
• Textolite for the manufacture of microcircuits.
• Material for the housing of a future amplifier.
• Electrical parts specified in schematic diagram products.
• Circuit board diagram of the amplifier selected for assembly.

DIY printed circuit board

Each business has its own subtleties. Making a printed circuit board at home is no exception. It is this that will subsequently become the basis for all further work and will allow you to assemble a sound amplifier with your own hands. First let's look at everything we need:

• Textolite with copper foil.
• Household iron.
• Detergent "Silit".
• Laser printer.
• Chinese self-adhesive film with backing marking 333.
• Drills for making holes in PCB.
• A tampon made of gauze and a piece of cotton fabric.

• We cut out the required piece of PCB so that there is approximately one centimeter of margin left on each side.
• Let's process it detergent until the copper foil turns pink.
• We wash the processed board and send it to dry.
• We take a piece of self-adhesive of the required size, use glue to glue it with a backing to an A4 sheet, remove the film layer, and print the design of the future board on the polished side of the resulting blank. In this case, the toner supply must be set to maximum.
• On the desktop we lay out a sheet of plywood, an old unnecessary book, and on top - a board with the foil facing up.
• Cover the board with regular office paper and heat it with a preheated iron. Approximate warm-up time is one minute.
• Next, remove the iron and sheet of paper, apply the printed design and smooth it with a swab.
• Cover again with a sheet of paper, place the iron on top and wait about 30 seconds. If the surface of the board is larger than the sole of the iron, then you need to iron the entire part evenly.
• Remove the sheet of paper and smooth the pattern with a swab for 30 seconds. Movements should be both along and across. In this case, you need to apply a little pressure on the workpiece.
• After the workpiece has cooled, carefully remove the backing.

How and with what to etch the board

In order to properly assemble a sound amplifier with your own hands, it is not enough to correctly draw the board design or solder the wire. You need to be able to efficiently etch all the tracks on the microcircuit.

Ferric chloride has always been used for these purposes. However, this solution is very expensive and is not always commercially available. For this reason, it can be replaced with a homemade solution of copper sulfate and table salt, which are not in short supply. The proportions for the mixture are as follows:

• A liter of warm water.
• 100 g copper sulfate.
• 200 g kitchen salt.

When all components are dissolved, clean and fat-free ingredients are lowered into the container. hardware(for example, a pair of nails), the workpiece itself, a small motor with blades or a compressor from an aquarium. To enhance the reaction, place the container with the solution in warm water. The approximate time for etching tracks is 25-30 minutes.

Amplifier assembly

The first step that needs to be done in order to assemble a sound amplifier with your own hands is to install all the radio components on the printed circuit board. Particular attention should be paid to polarity here. It would also be useful to note that all work should be carried out with special care and attention. Otherwise, a short circuit may occur, which will lead to inevitable failure of the components of the future amplifier.

After the above procedure, the housing assembly follows. Its dimensions will directly depend on the dimensions of the amplifier board, power supply and the method of implementing volume control and balance between channels. At this stage, you can use a ready-made factory case with some design changes. However, the most the best way However, manual production of the shell of an electrical appliance is still necessary. In this way it is possible to create unique design. There is also the option of installing a board in the housing of one of the speakers.

Before putting everything together, it is necessary to conduct a test run of the future electrical appliance and, if necessary, eliminate all problems.

The last step is assembling the amplifier, which consists of installing the board, power supply and all other components.

A little off topic

When assembling audio power amplifiers with your own hands, it is not always possible to achieve the desired effect. The secret is that the so-called acoustics are not able to cope with the tasks assigned to them. For this reason, sometimes it is necessary to additionally produce self-assembly even speakers. This approach to the issue will not only guarantee maximum satisfaction of all wishes, but will also help get rid of a separate device by hiding the amplifier in the speaker housing.

There were already publications on Habré about DIY tube amplifiers, which were very interesting to read. There is no doubt that their sound is wonderful, but for everyday use it is easier to use a device with transistors. Transistors are more convenient because they do not require warming up before operation and are more durable. And not everyone will risk starting a tube saga with anode potentials of 400 V, but transistor transformers of a couple of tens of volts are much safer and simply more accessible.

As a circuit for reproduction, I chose a circuit from John Linsley Hood from 1969, taking the author’s parameters based on the impedance of my 8 Ohm speakers.

The classic circuit from a British engineer, published almost 50 years ago, is still one of the most reproducible and receives extremely positive reviews. There are many explanations for this:
- the minimum number of elements simplifies installation. It is also believed that the simpler the design, the better the sound;
- despite the fact that there are two output transistors, they do not need to be sorted into complementary pairs;
- an output of 10 Watts is sufficient for ordinary human dwellings, and an input sensitivity of 0.5-1 Volts agrees very well with the output of most sound cards or players;
- class A - it is also class A in Africa, if we are talking about good sound. Comparison with other classes will be discussed below.

Interior design

An amplifier starts with power. It is best to separate two channels for stereo using two different transformers, but I limited myself to one transformer with two secondary windings. After these windings, each channel exists on its own, so we must not forget to multiply by two everything mentioned below. On a breadboard we make bridges using Schottky diodes for the rectifier.

It is possible with ordinary diodes or even ready-made bridges, but then they need to be bypassed with capacitors, and the voltage drop across them is greater. After the bridges there are CRC filters consisting of two 33000 uF capacitors and a 0.75 Ohm resistor between them. If you take a smaller capacitance and a resistor, the CRC filter will become cheaper and heat up less, but the ripple will increase, which is not comme il faut. These parameters, IMHO, are reasonable from a price-effect point of view. A powerful cement resistor is needed for the filter; at a quiescent current of up to 2A, it will dissipate 3 W of heat, so it is better to take it with a margin of 5-10 W. For the remaining resistors in the circuit, 2 W of power will be quite enough.

Next we move on to the amplifier board itself. Online stores sell a lot of ready-made kits, but there are no fewer complaints about the quality of Chinese components or illiterate layouts on boards. Therefore, it’s better to do it yourself, at your own discretion. I made both channels on a single breadboard so that I could later attach it to the bottom of the case. Running with test elements:

Everything except the output transistors Tr1/Tr2 is on the board itself. The output transistors are mounted on radiators, more on that below. The following remarks should be made to the author’s diagram from the original article:

Not everything needs to be soldered tightly at once. It is better to first set up resistors R1, R2 and R6 as trimmers, unsolder them after all adjustments, measure their resistance and solder the final constant resistors with the same resistance. The setup comes down to the following operations. First, using R6, it is set so that the voltage between X and zero is exactly half of the voltage +V and zero. In one of the channels I didn’t have enough 100 kOhm, so it’s better to take these trimmers with a reserve. Then, using R1 and R2 (maintaining their approximate ratio!) the quiescent current is set - we set the tester to measure direct current and measure this very current at the positive input point of the power supply. I had to significantly reduce the resistance of both resistors to obtain the required quiescent current. The quiescent current of an amplifier in class A is maximum and, in fact, in the absence of an input signal, all goes into thermal energy. For 8-ohm speakers, this current, according to the author's recommendation, should be 1.2 A at a voltage of 27 Volts, which means 32.4 Watts of heat per channel. Since setting the current can take several minutes, the output transistors must already be on cooling radiators, otherwise they will quickly overheat and die. Because they are mostly heated.

It is possible that, as an experiment, you will want to compare the sound of different transistors, so you can also leave the possibility of convenient replacement for them. I tried 2N3906, KT361 and BC557C at the input, there was a slight difference in favor of the latter. In the pre-weekend we tried KT630, BD139 and KT801, and settled on imported ones. Although all of the above transistors are very good, the difference may be rather subjective. At the output, I immediately installed 2N3055 (ST Microelectronics), since many people like them.

When adjusting and lowering the resistance of the amplifier, the low-frequency cutoff frequency may increase, so for the input capacitor it is better to use not 0.5 µF, but 1 or even 2 µF in a polymer film. There is still a Russian picture-scheme of “Ultralinear Class A Amplifier” floating around the Internet, where this capacitor is generally proposed as 0.1 uF, which is fraught with a cutoff of all bass at 90 Hz:

They write that this circuit is not prone to self-excitation, but just in case, a Zobel circuit is placed between point X and ground: R 10 Ohm + C 0.1 μF.
- fuses, they can and should be installed both on the transformer and on the power input of the circuit.
- it would be very appropriate to use thermal paste for maximum contact between the transistor and the heatsink.

Metalworking and carpentry

Now about the traditionally most difficult part in DIY - the housing. The dimensions of the case are determined by radiators, and in class A they must be large, remember about 30 watts of heat on each side. At first, I underestimated this power and made a case with average radiators of 800 cm² per channel. However, with the quiescent current set to 1.2A, they heated up to 100°C in just 5 minutes, and it became clear that something more powerful was needed. That is, you need to either install larger radiators or use coolers. I didn’t want to make a quadcopter, so I bought giant, handsome HS 135-250 with an area of ​​2500 cm² for each transistor. As practice has shown, this measure turned out to be a little excessive, but now the amplifier can be easily touched with your hands - the temperature is only 40°C even in rest mode. Drilling holes in the radiators for mounts and transistors became a bit of a problem - the initially purchased Chinese metal drills were drilled extremely slowly, each hole would have taken at least half an hour. Cobalt drills with a sharpening angle of 135° from a well-known German manufacturer came to the rescue - each hole is passed in a few seconds!

I made the body itself from plexiglass. We immediately order cut rectangles from glaziers, make the necessary holes for fastenings in them and paint them with reverse side black paint.

The plexiglass painted on the reverse side looks very beautiful. Now all that remains is to assemble everything and enjoy the music... oh yes, during final assembly it is also important to properly distribute the ground to minimize the background. As was discovered decades before us, C3 must be connected to the signal ground, i.e. to the minus of the input-input, and all other minuses can be sent to the “star” near the filter capacitors. If everything is done correctly, then you won’t be able to hear any background, even if you bring your ear to the speaker at maximum volume. Another “ground” feature that is typical for sound cards that are not galvanically isolated from the computer is interference from the motherboard, which can get through USB and RCA. Judging by the Internet, the problem occurs frequently: in the speakers you can hear the sounds of the HDD, printer, mouse and the background power supply of the system unit. In this case, the easiest way to break the ground loop is to cover the ground connection on the amplifier plug with electrical tape. There is nothing to fear here, because... There will be a second ground loop through the computer.

I did not make a volume control on the amplifier, since I was unable to get any high-quality ALPS, and I did not like the rustling of Chinese potentiometers. Instead, a regular 47 kOhm resistor was installed between ground and the input signal. Moreover, the regulator on an external sound card is always at hand, and every program also has a slider. Only the vinyl player does not have a volume control, so to listen to it I attached an external potentiometer to the connecting cable.

I can guess this container in 5 seconds...

Finally, you can start listening. The sound source is Foobar2000 → ASIO → external Asus Xonar U7. Microlab Pro3 speakers. The main advantage of these speakers is a separate block of its own amplifier on the LM4766 chip, which can be immediately removed somewhere away. An amplifier from a Panasonic mini-system with a proud Hi-Fi inscription or an amplifier from the Soviet Vega-109 player sounded much more interesting with this acoustics. Both of the above devices operate in class AB. JLH, presented in the article, beat all the above-mentioned comrades by one wicket, according to the results of a blind test for 3 people. Although the difference was audible to the naked ear and without any tests, the sound was clearly more detailed and transparent. It's quite easy, for example, to hear the difference between MP3 256kbps and FLAC. I used to think that the lossless effect was more like a placebo, but now my opinion has changed. Likewise, it has become much more pleasant to listen to files uncompressed from loudness war - dynamic range less than 5 dB is not ice at all. Linsley-Hood is worth the investment of time and money, because a similar brand amp will cost much more.

Material costs

Transformer 2200 rub.
Output transistors (6 pcs. with a reserve) 900 rub.
Filter capacitors (4 pcs) 2700 rub.
“Rassypukha” (resistors, small capacitors and transistors, diodes) ~ 2000 rub.
Radiators 1800 rub.
Plexiglas 650 rub.
Paint 250 rub.
Connectors 600 rub.
Boards, wires, silver solder, etc. ~1000 rub.
TOTAL ~12100 rub.

Scheme simple amplifier sound on transistors, which is implemented on two powerful composite transistors TIP142-TIP147 installed in the output stage, two low-power BC556B in the differential path and one BD241C in the signal pre-amplification circuit - a total of five transistors for the entire circuit! This design of the UMZCH can be freely used, for example, as part of a home music center or to drive a subwoofer installed in a car or at a disco.

The main attractiveness of this audio power amplifier lies in the ease of its assembly even by novice radio amateurs; there is no need for any special configuration, and there are no problems in purchasing components at an affordable price. The mind diagram presented here has electrical characteristics with high linearity of operation in the frequency range from 20Hz to 20000Hz. p>

When choosing or self-production transformer for the power supply, the following factor must be taken into account: - the transformer must have sufficient power reserve, for example: 300 W per channel, in the case of a two-channel version, then naturally the power doubles. You can use a separate transformer for each, and if you use a stereo version of the amplifier, then you will generally get a “dual mono” type device, which will naturally increase the efficiency of sound amplification.

The effective voltage in the secondary windings of the transformer should be ~34v AC, then the constant voltage after the rectifier will be in the region of 48v - 50v. In each power supply arm it is necessary to install a fuse designed for an operating current of 6A, respectively, for stereo when operating on one power supply - 12A.