Do-it-yourself audio amplifier for a computer. Do-it-yourself high-quality sound amplifier. Connecting and setting up homemade and factory audio devices

Having bought a good laptop or a cool phone, we rejoice at the purchase, admiring the many functions and speed of the device. But as soon as we connect the gadget to the speakers to listen to music or watch a movie, we understand that the sound produced by the device, as they say, “let us down.” Instead of full and clear sound, we hear an unintelligible whisper with background noise.

But don’t get upset and scold the manufacturers; you can solve the sound problem yourself. If you know a little about microcircuits and know how to solder well, then it will not be difficult for you to make your own audio amplifier. In our article we will tell you how to make a sound amplifier for each type of device.

At the initial stage of creating an amplifier, you need to find tools and buy components. The amplifier circuit is made on a printed circuit board using a soldering iron. To create microcircuits, use special soldering stations that can be bought in the store. The use of a printed circuit board allows you to make the device compact and easy to use.

Do not forget about the features of compact single-channel amplifiers based on TDA series microcircuits, the main one of which is the release of a large amount of heat. Therefore, when designing the internal structure of the amplifier, try to prevent the microcircuit from coming into contact with other parts. For additional cooling of the amplifier, it is recommended to use a radiator grille to dissipate heat. The size of the grid depends on the model of the microcircuit and the power of the amplifier. Plan in advance a place for the heat sink in the amplifier case.
Another feature of making your own sound amplifier is low energy consumption. This in turn allows you to use the amplifier in a car by connecting it to a battery or on the road using battery power. Simplified models amplifiers require a current voltage of only 3 volts.

If you are a beginner radio amateur, then for more convenient work, we recommend that you use a special computer program - Sprint Layout. With this program you can independently create and view diagrams on your computer. Please note that creating your own scheme only makes sense if you have sufficient experience and knowledge. If you are an inexperienced radio amateur, then use ready-made and proven circuits.

Below we provide diagrams and descriptions different options sound amplifier:

Headphone amplifier

The sound amplifier for portable headphones is not very powerful, but consumes very little energy. This is an important factor for mobile amplifiers that are powered by batteries. You can also place a connector on the device for power supply via a 3 volt adapter.

To make a headphone amplifier you will need:

• Chip TDA2822 or analogue KA2209.
• Amplifier assembly diagram.
• Capacitors 100 uF 4 pieces.
• Headphone jack.
• Adapter connector.
• Approximately 30 centimeters of copper wire.
• Heat sink element (for a closed case).

The amplifier is manufactured on a printed circuit board or mounted. Do not use a pulse transformer with this type of amplifier as it may cause interference. After manufacturing, this amplifier is capable of providing powerful and pleasant sound from a phone, player or tablet.
With one more option homemade amplifier for headphones, you can watch the video:

Sound amplifier for laptop

An amplifier for a laptop is assembled in cases where the power of the speakers built into it is not enough for normal listening, or if the speakers are out of order. The amplifier must be designed for external speakers up to 2 watts and winding resistance up to 4 ohms.

To assemble the amplifier you will need:

• Printed circuit board.
• Chip TDA 7231.
• 9 volt power supply.
• Housing for placing components.
• Non-polar capacitor 0.1 µF - 2 pieces.
• Polar capacitor 100 uF - 1 piece.
• Polar capacitor 220 uF - 1 piece.
• Polar capacitor 470 uF - 1 piece.
• Constant resistor 10 Kom - 1 piece.
• Constant resistor 4.7 Ohm - 1 piece.
• Two-position switch - 1 piece.
• Loudspeaker input jack - 1 piece.

The assembly order is determined independently depending on the diagram. The cooling radiator must be of such a size that the operating temperature inside the amplifier case does not exceed 50 degrees Celsius. If you plan to use the device outdoors, then you need to make a case for it with holes for air circulation. For the case, you can use a plastic container or plastic boxes from old radio equipment.
You can watch the visual instructions in the video:

Sound amplifier for car radio

This amplifier for car radio is assembled on TDA chip 8569Q, the circuit is not complicated and very common.

The microcircuit has the following declared characteristics:

• Input power is 25 watts per channel into 4 ohms and 40 watts per channel into 2 ohms.
• Supply voltage 6-18 volts.
• Reproducible frequency range 20-20000 Hz.

For use in a car, a filter must be added to the circuit to prevent interference generated by the generator and ignition system. The microcircuit also has protection against output short circuit and overheating.

Referring to the diagram presented, purchase the necessary components. Next, draw the circuit board and drill holes in it. After this, etch the board with ferric chloride. Finally, we tinker and begin to solder the components of the microcircuit. Please note that it is better to cover the power paths with a thicker layer of solder so that there are no power drawdowns.
You need to install a radiator on the chip or organize active cooling using a cooler, otherwise the amplifier will overheat at increased volume.
After assembling the microcircuit, it is necessary to make a power filter according to the diagram below:

The choke in the filter is wound in 5 turns, with a wire with a cross-section of 1-1.5 mm, on a ferite ring with a diameter of 20 mm.
This filter can also be used if your radio picks up interference.
Attention! Be careful not to reverse the polarity of the power supply, otherwise the microcircuit will burn out instantly.
You can also learn how to make an amplifier for a stereo signal from the video:

Transistor sound amplifier

As a circuit for a transistor amplifier, use the circuit below:

The scheme, although old, has a lot of fans, for the following reasons:

• Simplified installation due to the small number of elements.
• There is no need to sort transistors into complementary pairs.
• 10 watts of power, sufficient for living rooms.
• Good compatibility with new sound cards and players.
• Excellent sound quality.

Start assembling the amplifier with the power supply. Separate the two channels for stereo with two secondary windings coming from the same transformer. On the breadboard, make bridges using Schottky diodes for the rectifier. After the bridges there are CRC filters consisting of two 33,000 uF capacitors and a 0.75 Ohm resistor between them. 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, a power of 2 W will be enough.

Let's move on to the amplifier board. Everything except the output transistors Tr1/Tr2 is on the board itself. The output transistors are mounted on radiators. 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 setting comes down to the following operations - using R6, it is set so that the voltage between X and zero is exactly half of the voltage +V and zero. Then, using R1 and R2, the quiescent current is set - set the tester to measure direct current and measure the current at the power supply plus entry point. The quiescent current of an amplifier in class A is maximum and, in fact, in the absence of an input signal, all of it goes into thermal energy. For 8 ohm speakers, this current should be 1.2 A at 27 volts, which means 32.4 watts of heat per channel. Since setting the current can take several minutes, the output transistors should already be on cooling radiators, otherwise they will quickly overheat.
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. It is believed 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 must be placed both on the transformer and on the power input of the circuit.
It is a good idea to use thermal paste to ensure maximum contact between the transistor and the heatsink.
Now a few words about the case. The size of the case is determined by radiators - NS135-250, 2500 square centimeters for each transistor. The body itself is made of plexiglass or plastic. Having assembled the amplifier, before you start enjoying the music, it is necessary to properly distribute the ground to minimize background noise. To do this, connect the SZ to the minus of the input-output, and connect the remaining minuses to the “star” near the filter capacitors.

Approximate cost of consumables for a transistor audio amplifier:

• Filter capacitors 4 pieces - 2700 rubles.
• Transformer - 2200 rubles.
• Radiators - 1800 rubles.
• Output transistors - 6-8 pieces, 900 rubles.
• Small elements (resistors, capacitors, transistors, diodes) about 2000 rubles.
• Connectors - 600 rubles.
• Plexiglas - 650 rubles.
• Paint - 250 rubles.
• Board, wires, solder about - 1000 rubles

The resulting amount is 12,100 rubles.
You can also watch a video on assembling an amplifier using germanium transistors:

Tube sound amplifier

The circuit of a simple tube amplifier consists of two stages - a 6N23P pre-amplifier and a 6P14P power amplifier.

As can be seen from the diagram, both cascades operate in triode connection, and the anode current of the lamps is close to the limit. The currents are adjusted by cathode resistors - 3mA for the input and 50mA for the output lamp.
Parts used for a tube amplifier must be new and of high quality. Tolerance resistor values ​​can be plus or minus 20%, and the capacitance of all capacitors can be increased by 2-3 times.
Filter capacitors must be designed for a voltage of at least 350 volts. The interstage capacitor must also be designed for the same voltage. Transformers for the amplifier can be ordinary - TV31-9 or a more modern analogue - TWSE-6.

It is better not to install a stereo volume and balance control on the amplifier, since these adjustments can be made in the computer or player itself. The input lamp is selected from - 6N1P, 6N2P, 6N23P, 6N3P. The output pentode is 6P14P, 6P15P, 6P18P or 6P43P (with increased cathode resistor resistance).
Even if you have a working transformer, it is better to use a regular transformer with a 40-60 watt rectifier to turn on the claw amplifier for the first time. Only after successful testing and tuning of the amplifier can the pulse transformer be installed.
Use standard sockets for plugs and cables; to connect speakers, it is better to install 4-pin “pedals”.
The housing for the claw amplifier is usually made from the shell of old equipment or system unit cases.
You can watch another version of a tube amplifier in the video:

Classification of sound amplifiers

So that you can determine which class of sound amplifiers the device you assembled belongs to, read the UMZCH classification below:

• • Class A- amplifiers of this class operate without signal cutoff in the linear portion of the current-voltage characteristic of the amplifying elements, which ensures a minimum of nonlinear distortions. But this comes at the cost of a large amplifier and huge power consumption. The efficiency of a Class A amplifier is only 15-30%. This class includes tube and transistor amplifiers.

• • Class B- Class B amplifiers operate with a signal cutoff of 90 degrees. For this mode of operation it is used push-pull circuit, in which each part amplifies its half of the signal. The main disadvantage of class B amplifiers is signal distortion due to a stepwise transition from one half-wave to another. Plus of this class amplifiers are considered high efficiency, sometimes reaching 70%. But despite the high performance, you will not find modern class B amplifier models on the shelves.

• • Class AB is an attempt to combine amplifiers of the classes described above in order to achieve the absence of signal distortion and high efficiency.

• • Class H- designed specifically for cars that have a limitation of the voltage supplying the output stages. The reason for the creation of Class H amplifiers is that the real audio signal is pulsed in nature and its average power is much lower than the peak power. The circuit of this class of amplifiers is based on a simple circuit for a class AB amplifier operating in a bridge circuit. Only a special circuit for doubling the supply voltage has been added. The main element of the doubling circuit is a large-capacity storage capacitor, which is constantly charged from the main power source. At power peaks, this capacitor is connected by the control circuit to the main power supply. The supply voltage to the amplifier's output stage is doubled, allowing it to handle signal peaks. The efficiency of class H amplifiers reaches 80%, with signal distortion of only 0.1%.

• Class D is a separate class of amplifiers called “digital amplifiers”. Digital conversion provides additional sound processing capabilities: from adjusting volume and tone to implementing digital effects such as reverberation, noise reduction, acoustic suppression feedback. Unlike analog amplifiers, the output of Class D amplifiers is a square wave. Their amplitude is constant, but their duration varies depending on the amplitude of the analog signal entering the amplifier input. The efficiency of amplifiers of this type can reach 90% -95%.

In conclusion, I would like to say that working in radio electronics requires a large amount of knowledge and experience, which is acquired over a long time. Therefore, if something doesn’t work out for you, don’t be discouraged, reinforce your knowledge from other sources and try again!

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 dimensions. 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 that are indicated in the circuit diagram of the product.
• 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.
• We treat it with 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 of copper sulfate.
• 200 g kitchen salt.

When all the components are dissolved, clean and grease-free metal products (for example, a pair of nails), the workpiece itself, a small motor with blades or a compressor from an aquarium are lowered into the container. 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 worth noting 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 body with the addition of some constructive changes. However, the most the best way still is handmade electrical appliance shell. This way you can realize the possibility of creating a 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 you have to additionally assemble even the speakers yourself. 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.

Evgenia Smirnova

To send light into the depths of the human heart - this is the purpose of the artist

Content

Connecting speakers to a laptop, TV, or other music source sometimes requires amplification of the signal using a separate device. The idea of ​​building your own amplifier is a good one if you are inclined to work with printed circuit boards at home and have some technical skills.

How to make a sound amplifier

The beginning of work on assembling an amplification device for speakers of one type or another consists of searching for tools and components. The amplifier circuit is assembled on a printed circuit board using a soldering iron on a heat-resistant support. It is recommended to use special soldering stations. If the DIY assembly is carried out for the purpose of testing the circuit or for use for a short period of time, the “on wires” option is suitable, but you will need more space for placing components. The printed circuit board guarantees the compactness of the device and ease of further use.

A cheap and widespread amplifier for headphones or small speakers is created on the basis of a microcircuit - a miniature control unit with a pre-wired set of commands for controlling an electrical signal. All that remains to be added to the circuit with the microcircuit is a few resistors and capacitors. The total cost of an amateur-grade amplifier is ultimately significantly lower than the price of ready-made professional equipment from the nearest store, but the functionality is limited to changing the output volume of the audio signal.

Remember the features of compact single-channel amplifiers that you assemble yourself based on TDA series microcircuits and their analogues. The microcircuit highlights a large number of heat during operation, so you must eliminate or minimize its contact with other parts of the device. A radiator grille for heat dissipation is recommended for use. Depending on the model of the microcircuit and the power of the amplifier, the size of the required heatsink increases. If the amplifier is assembled in a housing, you should first plan a place for the heat sink.

Another feature of assembling a sound amplifier with your own hands is the low voltage consumption. This allows you to use a simple amplifier in cars (powered by a car battery), on the road or at home (powered by a special unit or batteries). Some simplified audio amplifiers require a voltage of only 3 Volts. Power consumption depends on what level of amplification sound signal required. The sound amplifier from the player for standard headphones consumes about 3 Watts.

It is recommended for a novice radio amateur to use a computer program to create and view circuit diagrams. Files for such programs can have a *.lay extension - they are created and edited in the popular virtual tool Sprint Layout. Creating a circuit with your own hands from scratch makes sense if you have already gained experience and want to experiment with the knowledge you have gained. Otherwise, look for and download ready-made files that can be used to quickly assemble a replacement for a low-frequency amplifier for a car radio or a digital combo amplifier for a guitar.

For laptop

A do-it-yourself sound amplifier for a laptop is assembled in one of two cases: the built-in speakers are out of order, or their volume and sound quality are not enough for your needs. You will need a simple amplifier designed for a power of external speakers up to 2 Watts, and a winding resistance of up to 4 Ohms. To assemble it yourself, in addition to standard amateur radio tools (pliers, Soldering Station) you will need a printed circuit board, a TDA 7231 microcircuit, and a 9 Volt power supply. Select your own housing to house the amplifier components.

Add the following items to the list of purchased components:

• non-polar capacitor 0.1 µF – 2 pcs.;
• polar capacitor 100 µF – 1 pc.;
• polar capacitor 220 µF – 1 pc.;
• polar capacitor 470 µF – 1 pc.;
• constant resistor 10 KOhm – 1 pc.;
• constant resistor 4.7 Ohm – 1 pc.;
• two-position switch – 1 pc.;
• jack for loudspeaker output – 1 pc.

Determine the assembly order yourself depending on which *.lay electrical diagram you downloaded. Select a radiator of such a size that its thermal conductivity allows you to maintain the operating temperature of the microcircuit below 50 degrees Celsius. If the device is regularly used outdoors with a laptop, it will need homemade body with slits or holes for air circulation. You can assemble such a case with your own hands from plastic container or remnants of old radio equipment, securing the board with long screws.

For DIY headphones

The simplest stereo amplifier for portable headphones should have low power, but the most important parameter will be power consumption. In an ideal example, the design is powered by AA batteries, as a last resort, from a simple 3 Volt adapter. You will need a high quality TDA 2822 chip or its equivalent (for example, KA 2209), electronic circuit DIY amplifier assembly using TDA 2822. Additionally, take the following components:

• capacitors 100 µF (4 pcs.);
• up to 30 cm of copper wire;
• headphone socket.

A heat sink element will be needed if you want to make the amplifier compact and with a closed housing. The amplifier can be assembled on a ready-made or home-made printed circuit board or by surface mounting. The pulse transformer in the power supply may cause interference, so do not use it in this option amplifier The finished amplifier will provide pleasant and powerful sound from the player (record or radio signal), tablet or phone.

Subwoofer amplifier circuit

The low-frequency amplifier is assembled with your own hands on the TDA 7294 microcircuit. It is used both to create powerful acoustics with bass in the apartment, and as a car amplifier - in this case, however, you need to purchase a bipolar power supply of 30-35 Volts. The figures below describe the location of components, as well as the values ​​of resistors and capacitors. This subwoofer amplifier will provide output power up to 100 watts with outstanding low frequencies.

Mini sound amplifier for speakers

The design described above for laptops is suitable as a sound amplification device for domestic or foreign home speakers. Stationary placement of the device will allow you to choose any power adapter from those available. Miniature and acceptable appearance You can provide an inexpensive amplifier by following several rules:

1. Ready-made high-quality printed circuit board.
2. Durable plastic or metal case (order from a specialist).
3. The placement of components is pre-planned.
4. The amplifier is soldered neatly, without unnecessary drops of solder.
5. The heatsink only touches the chip.
6. Ready-made sockets are used for signal output and power input.

DIY tube sound amplifier

Tube sound amplifiers are expensive devices, provided that you purchase all components locally. own funds. Old radio amateurs sometimes keep collections of tubes and other parts. Assembling a tube amplifier at home with your own hands is relatively easy if you are willing to spend a few days searching for detailed circuit diagrams on the Internet. The sound amplifier circuit in each case is unique and depends on the sound source (old tape recorder, modern digital equipment), power source, expected dimensions and other parameters.

Transistor sound amplifier

Assembling a sound preamplifier with your own hands without using complex microcircuits possible with transistors. An amplifier based on germanium transistors can be easily integrated into modern audio systems; it does not require additional configuration. The disadvantage of transistor circuits is considered larger size assembled boards. The dependence on the “purity” of the background is also unpleasant - you will need a shielded cable, or an additional circuit for suppressing noise and ripple from the network.

Video: DIY audio power amplifier

Sometimes connecting speakers to a TV, laptop or other similar music source requires signal amplification through a certain device. If you have basic technical knowledge, you can make an amplifier at home with your own hands.

How to create a sound amplifier correctly

First of all, to assemble such a device for speakers, you will need tools, as well as the required components. Circuits of the simplest amplifiers are assembled using a soldering iron placed on a support high degree sustainability. It is advisable to use certain soldering stations.

In the process of personally assembling an amplifier to test the corresponding circuit, or use it for a short period of time, good option There will be a model on a wire, but it will require a lot of free space to arrange the components.

The printed circuit board guarantees maximum compactness of the device and convenient use in the future.

A popular and affordable amplifier, intended for headphones or small speakers, is made on the basis of a microcircuit that represents a small-sized control unit with a built-in set of commands for controlling the electrical signal.

A pair of resistors and, of course, capacitors should be connected to the circuit with the desired microcircuit. IN total the price of an amplifier assembled by yourself will be much lower than the cost of equipment purchased in a specialized store, while the limitation of functionality is changing the signal volume.

Do not forget about the features of single-channel amplifiers, self-production which is carried out on the basis of both TDA schemes and their analogues.

The circuit generates a lot of heat during the operating process; it is for this reason that its contact with the elements of the device should be minimized. A radiator grille designed for heat dissipation is desirable for use.

Depending on the purchased microcircuit, as well as the power of the device, the size of the required radiator increases. When assembling the amplifier inside the housing part, you need to think in advance about the space provided under the heat sink.

Another feature of creating an amplifier with your own hands, as shown in the photo, is the minimum power consumption, which makes it possible to use a simplified amplifier in cars, on the road, or at home. Some simple amplifiers Just a few volts is enough.

The power consumed directly depends on required level signal amplification. The audio amplifier from the player used for the required headphones consumes approximately 3 W.

To make circuits, it is better for an inexperienced radio amateur to use special program, for which the files have the required extension.

Creating the necessary circuit yourself is possible if you have certain knowledge and the desire to experiment with it. Otherwise, it is better to download files for quickly assembling a replacement amplifier of the lowest possible frequency.

For laptop

The instructions on how to make an amplifier for a laptop with your own hands provide for assembling such a device in such cases: the built-in speakers are broken or have low volume quality.

You will need a regular amplifier with a power of several watts and a winding resistance of 40 ohms. In addition to the usual tools, assembly requires a printed circuit board, power supply and microcircuit. Choose your own housing where the amplifier elements will be located.

The assembly process should depend on the downloaded chip format. The radiator is selected in such a way that thermal conductivity makes it possible to maintain the required temperature regime microcircuits.

If the device is constantly used along with a laptop outside the room, then it will need a self-made case with certain slots or holes so as not to impede air circulation.

Such a case is assembled from a plastic container or the remains of failed equipment, and the board is secured with screws.

Tube amplifier

This DIY amplifier, as in the photo, is a fairly expensive device if you buy all the components.

Some radio amateurs have lamps and other necessary parts in stock. Assembling a tube-type amplifier at home is not considered complicated matter, if you can spend time searching for the necessary schemes on the RuNet.

If you need to find out what types of amplifiers there are, it is important to understand that their circuit in each individual version is unique, and also depends directly on the sound source, size, and other important parameters.

Photos of DIY amplifiers

- this is a device using field-effect transistors in the output path, implemented according to a “floating ground” circuit. That is, a “floating” ground is formed when the common wire of some part of the system is not electrically connected to the ground bus. During the existence of this amplifier circuit, significant changes were made to it, which to a greater extent promoted specifications UMZCH.

Power amplifier circuit model 2016.

Creating a device with a “virtual zero” or, as they say, a “midpoint” has its own characteristics: DIY sound amplifier for speakers does not require setting the voltage to “zero”; there is no need to protect the speaker system from constant output; The manufacture of a power transformer is greatly facilitated. For a constant-midpoint terminal circuit, two pairs of separate windings are required on one core, or two trances with two windings are required.

A little about testing and measuring the characteristics of an early version of this device, which was also assembled using MOSFET transistors in the output stage. Measurement of parameters showed the obvious presence of interference from the network in the input circuit of the UMZCH. And if we compare it with an amplifier with an average constant point, then there is a huge amount of interference multiples of a frequency of 50 Hz in a range of up to 1 kHz.

Reduced interference

To radically reduce the amount of radio interference appearing in the input circuit of the amplifier through a constant resistor R3, it was decided: to implement a voltage bias circuit to the control electrode (gate) of field-effect transistor Q2 with complete symmetry in alternating voltage. Based on the fact that resistors R4 and R11 are identical and a capacitive circuit C4-C6 has also been added, then by selecting the value of resistors R5-R12 you can set an acceptable bias voltage for input key. In addition, the containers C4-C6 included in the circuit are filtered AC voltage appearing at the terminals of current sources.

At the model construction stage DIY sound amplifier for speakers demanded to carefully study the problem of generating an apparatus at super low frequencies in the range below 20 Hz. Namely, when the total capacitance of the capacitors in the power circuit is too small and the capacitance at the C1 input is significant. Thus, the amplifier’s disposition to self-excitation is determined R-C chain by supply voltage R16-C5 (R17-C3), and naturally by capacitors in the power source. To provide the amplifier with conditions for stable and stable operation, the total capacitance of electrolytic capacitors in each arm of the power supply must be set to 10,000 µF with C1 up to 0.15 µF, 15,000 µF with C1 = 0.22 µF and 20,000 µF with C1 = 0.33 µF.

For high-quality sound reproduction at low frequencies, the input resistance of the UMZCH was increased. For this purpose, instead of a bipolar transistor, a MOSFET transistor Q2 was installed at the input, and instead of a current reflector, a current source was implemented in the primary stage. The second stage of the amplifier is assembled using a common emitter circuit design.

Amplifier reliability

To ensure reliable operation of the device, a pair of bipolar transistor Q11-Q15, which perform the function of limiting the peak current passing in the circuit of output transistors 7A-8A. In addition, a 1N4148 rectifier diode (D7) was added to the circuit to limit the forward and reverse voltage relative to the terminals of transistor Q14.

Important technical characteristics of the power amplifier:

The quiescent current in the circuit is set by variable resistor R23a (100 Ohm). The optimal quiescent current for normal operation of the device is needed within 80 mA. Even with this value of the quiescent current, the signal distortion at the output of this end amplifier is within 0.09% with a short instantly reducing harmonic range.

Upgraded power supply.

Power transformer

A 140 W power transformer is assembled on a toroidal core with two secondary windings having a voltage of ~36v each. The rectifier block consists of two diode bridges designed for a rated voltage of 100v and a current of 10A. According to the circuit, the rectifier filters are implemented on four 10,000 F capacitors for a voltage of 63v with a midpoint. Moreover, they are separate for each channel, and also without galvanic connection with a common bus. It is to these middle points that the speaker wires with the “-” sign from the left and right channels are supplied. Depending on the design of your transformer housing, you can install two transformers with a power of 70-80 W each. On electrolytic capacitors C3-C4, shunts in the form of paper capacitors C1-C2 must be installed in parallel.