Do-it-yourself low-frequency amplifiers. How to make a sound amplifier with your own hands from improvised means? Why do you need a car audio amplifier

- this is a field-effect transistor device in the output path implemented according to the "floating earth" scheme. That is, a “floating” earth 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 increased the technical characteristics of the UMZCH.

The scheme of the power amplifier sample of 2016.

The creation of an apparatus with a "virtual zero" or, as they say, a "middle point" has its own characteristics: DIY speaker amplifier does not require setting the voltage to "zero", does not require protection of the speaker system from constant output; the manufacture of a power transformer is greatly facilitated. A constant mid-point termination circuit requires two pairs of separate windings on the same core, or two trances with two windings.

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. The measurement of the parameters showed a clear presence of interference from the network in the input circuit of the UMZCH. And if you compare it with an amplifier with a mid-dc point, then there is a huge amount of noise in multiples of 50 Hz in the range up to 1 kHz.

Reducing the amount of interference

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

At the design stage of the model DIY speaker amplifier demanded to carefully work out the problem of generating the device at ultra-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 input C1 is significant. So, the location of the amplifier to self-excitation is determined by the R-C circuit for the supply voltage R16-C5 (R17-C3), and naturally by the capacitors in the power source. To provide the amplifier with conditions for stable and stable operation, the total capacitance of the electrolytic capacitors in each of the arms of the power supply must be set to 10000uF at C1 to 0.15uF, 15000uF at C1= 0.22uF and 20000uF at C1= 0.33uF.

For high-quality sound reproduction at low frequencies, the UMZCH input resistance 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 according to circuitry with a common emitter.

Amplifier Reliability

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

Important specifications of the power amplifier:

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

Upgraded power supply.

Power transformer

A power transformer with a power of 140 W is assembled on a toroidal core with two secondary windings having a voltage of ~ 36v each. The rectifier unit consists of two diode bridges designed for a nominal voltage of 100v and a current of 10A. The rectifier filters according to the scheme are implemented on four capacities of 10000 F each for a voltage of 63v with a midpoint. Moreover, separate for each channel, as well as without a galvanic connection with a common bus. It is to these midpoints that acoustic wires with a “-” sign are fed from the left and right channels. Depending on the design of your transformer housing, you can install two, with a power of 70-80 W each. Shunts in the form of paper capacitors C1-C2 should be placed in parallel on electrolytic containers C3-C4.

Having bought a good laptop or a cool phone, we are happy with the purchase, admiring the many features and speed of the device. But as soon as you 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 a full and clear sound, we hear an unintelligible whisper with background noise.

But do not 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 work on 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 chips, use special soldering stations that can be bought at the store. Using a printed circuit board allows you to make the device compact and easy to use.

Audio frequency amplifier

Do not forget about the features of compact single-channel amplifiers based on TDA series chips, the main of which is the generation of a large amount of heat. Therefore, try with the internal structure of the amplifier to exclude the contact of the microcircuit with other parts. For additional cooling of the amplifier, it is recommended to use a radiator grill to remove heat. The size of the grating depends on the model of the microcircuit and the power of the amplifier. Plan ahead for the location of the heat sink in the amplifier case.
Another feature of self-manufacturing audio amplifier is low power consumption. This, in turn, allows you to use the amplifier in the car by connecting it to the battery or on the road using battery power. Simplified amplifier models require a voltage of only 3 volts.

The main elements of the amplifier

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 create and view diagrams on your computer yourself. Please note that creating your own schema only makes sense if you have sufficient experience and knowledge. If you are an inexperienced radio amateur, then use ready-made and proven schemes.

Below we give diagrams and descriptions of different options for a sound amplifier:

Headphone Amplifier

The portable headphone amplifier is not very powerful, but consumes very little power. This is an important factor for mobile amplifiers that are powered by batteries. You can also put a connector on the device for mains power through a 3 volt adapter.

Homemade headphone amplifier

To make a headphone amplifier you will need:

Chip TDA2822 or equivalent KA2209.
Amplifier assembly diagram.
Capacitors 100uF 4 pieces.
Headphone jack.
Connector for adapter.
Approximately 30 centimeters of copper wire.
Heat sink element (for closed case).

Headphone amplifier circuit

The amplifier is made on a printed circuit board or surface-mounted. Do not use a pulse transformer in this type of amplifier, as it may cause interference. After manufacturing, this amplifier is able to provide a powerful and pleasant sound from a phone, player, or tablet.
You can see another version of a homemade headphone amplifier in the video:

Notebook sound amplifier

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.

Notebook sound amplifier

To assemble the amplifier you will need:

Printed circuit board.
Chip TDA 7231.
9 volt power supply.
Case for housing components.
Capacitor non-polar 0.1 uF - 2 pieces.
Capacitor polar 100 microfarad - 1 piece.
Capacitor polar 220 microfarad - 1 piece.
Capacitor polar 470 microfarad - 1 piece.
Resistor constant 10 Kom - 1 piece.
Resistor constant 4.7 Ohm - 1 piece.
Two-position switch - 1 piece.
Speaker input jack - 1 piece.

Laptop Sound Amplifier Circuit

The assembly order is determined independently depending on the scheme. 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 housing, you can use a plastic container or plastic boxes from old radio equipment.
You can see the visual instruction in the video:

Sound amplifier for car radio

This amplifier for a car radio is assembled on a TDA8569Q chip, the circuit is not complicated and very common.

Sound amplifier for car radio

The microcircuit has the following declared characteristics:

Input power 25 watts per channel into 4 ohms and 40 watts per channel into 2 ohms.
Supply voltage 6-18 volts.
The range of reproducible frequencies is 20-20000 Hz.

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

Sound amplifier circuit for car radio

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

Noise filter circuit

The inductor 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.
Also, this filter can be used if your radio catches "pickup".
Attention! Be careful not to reverse the polarity of the power supply, otherwise the chip will burn out instantly.
How to make an amplifier for a stereo signal, you can also learn from the video:

Transistor audio amplifier

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

Transistor audio amplifier circuit

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, with a margin enough for living rooms.
Good compatibility with new sound cards and players.
Excellent sound quality.

Start assembling the amplifier with power. Separate the two channels for stereo with two secondary windings coming from the same transformer. On the layout, make bridges on Schottky diodes for the rectifier. After the bridges, there are CRC filters of two 33,000 microfarad capacitors and a 0.75 ohm resistor between them. A powerful cement resistor is needed in the filter, with 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 rest of the resistors in the circuit, a power of 2 W will be enough.

transistor amplifier

Let's move on to the amplifier board. Everything except the output transistors Tr1/Tr2 is located on the board itself. The output transistors are mounted on heatsinks. It is better to put resistors R1, R2 and R6 first with trimmers, after all the adjustments, unsolder them, measure their resistance and solder the final fixed resistors with the same resistance. The setting comes down to the following operations - with the help of 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 - we set the tester to measure direct current and measure the current at the input point of the plus supply. The quiescent current of the amplifier in class A is maximum and, in fact, in the absence of an input signal, everything goes into thermal energy. For 8 ohm speakers this should be 1.2 amps at 27 volts, which means 32.4 watts of heat per channel. Since it can take several minutes for the current to be set, the output transistors must already be on the cooling heatsinks, otherwise they will quickly overheat.
When adjusting and lowering the resistance of the amplifier, the cutoff frequency of the low frequencies may increase, so for the capacitor at the input it is better to use not 0.5 microfarads, but 1 or even 2 microfarads 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 the X point and the ground: R 10 Ohm + C 0.1 microfarad. Fuses must be installed both on the transformer and on the power input of the circuit.
It's a good idea to use thermal paste to maximize contact between the transistor and the heatsink.
Now a few words about the body. The size of the case is set 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 dilute the ground to minimize the background. To do this, connect the SZ to the minus of the input-output, and bring the remaining minuses to the "star" near the filter capacitors.

Transistor audio amplifier housing

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 result is the amount - 12100 rubles.
You can also watch a video on assembling an amplifier based on germanium transistors:

Tube Sound Amplifier

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

Tube amplifier circuit

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

Tube Sound Amplifier

It is better not to install the 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. As an output pentode, 6P14P, 6P15P, 6P18P or 6P43P are used (with an increased resistance of the cathode resistor).
Even if you have a working transformer, it is better to use a conventional transformer with a 40-60 watt rectifier to turn on the paw amplifier for the first time. Only after a successful test and adjustment of the amplifier can a pulse transformer be installed.
Use standard sockets for plugs and cables; to connect speakers, it is better to install “pedals” on 4 pins.
The case for the paw amplifier is usually made from the shell of old equipment or cases of system units.
You can see another version of the tube amplifier in the video:

Classification of audio amplifiers

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

Class A Amplifier

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

Class B Amplifier

- Class B- Class B amplifiers operate with a 90 degree cutoff signal. For the mode of such operation, a push-pull circuit is used, 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. The advantage of this class of amplifiers is considered to be high efficiency, sometimes reaching 70%. But despite the high performance, you will not find modern class B amplifier models on the shelves.

Class AB Amplifier

- Class AB- this 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 Amplifier

- Class H- designed specifically for cars that have a voltage limit that feeds the output stages. The reason for the creation of class H amplifiers is that the real sound signal has a pulsed character and its average power is much lower than the peak. 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 scheme 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 power supply to the output stage of the amplifier is doubled, allowing it to cope with the transmission of signal peaks. The efficiency of class H amplifiers reaches 80%, with a signal distortion of only 0.1%.

Class D Amplifier

Class D is a separate class of amplifiers called "digital amplifiers". Digital conversion provides additional possibilities for sound processing: from adjusting the volume and tone to the implementation of digital effects such as reverb, noise reduction, acoustic feedback suppression. Unlike analog amplifiers, class D amplifiers output a square wave. Their amplitude is constant, and the 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 the occupation of radio electronics requires a large amount of knowledge and experience, which are acquired over a long period of time. Therefore, if something did not work out for you, do not be discouraged, reinforce your knowledge from other sources and try again!

We have repeatedly brought scheme powerful amplifiers low-frequency power for self-assembly, and today we will talk about the design of a fairly simple, but high-quality and painfully powerful amplifier for lanzar scheme. At all, scheme Lanzara has found wide distribution on the net, more and more people repeat this design, for high performance and relatively simple and cheap assembly, the circuit began to be used in industrial audio equipment.

Lanzar is implemented on 13 transistors, the circuit is completely symmetrical.
The output stage of the amplifier operates in class AB, the minimum coefficient of non-linear distortion allows the amplifier to be classified as a Hi-Fi (Hi-Fi). Such an amplifier is also great for powerful broadband speaker systems, but due to the relatively simple circuit decoupling and high output power, the amplifier is often repeated precisely to power fairly powerful subwoofer heads.

The peak output power of this amplifier is 390 watts into a 4 ohm load, but the amplifier works fine for low-impedance loads up to 2 ohms.

The archive has a fully working printed circuit board for this amplifier.

Assembly begins with etching of the PCB. For etching, I use a solution of hydrogen peroxide (3% solution, which is sold in pharmacies, 100 mg bottles), citric acid and table salt. The board is etched in a maximum of an hour, after which you need to wash off the toner and drill holes.

Installation starts with installation small components - resistors, zener diodes and ceramic capacitors. I advise you to carefully check all components before assembly, even if they are completely new. After that, we already solder the low-power transistors of the differential stages - where the initial sound is formed.

———————– The coil is wound on a frame with a diameter of 10-12 cm with a wire of 0.8 mm and contains 10-12 turns, the coil can even be removed, this will not affect the sound in any way.

The input capacitor is necessarily film, the capacitance can be selected in the regions of 1-4.7 μF, since the amplifier was originally designed for a subwoofer, and by increasing the capacitance of this capacitor, you can achieve the best reproduction of low frequencies (bass).

After the complete installation of all components, we wash off the rosin from the back of the board. DO NOT use all sorts of soldering fluxes with an unknown content, as they are often made on an acid basis, and it is because of the flux that you can burn the whole circuit. We strengthen the power tracks with tin, in order to avoid their burnout.

It is desirable to tin all tracks of the board before installation, since sooner or later copper oxidizes, and the tin layer forms additional protection.

Check carefully the correct connection of transistors, electrolytes and zener diodes, in order to avoid problems, you should use only those transistors that are indicated in the diagram, especially if you are a beginner or assembling a lanzar circuit for the first time. Zener diodes, if connected incorrectly, will not stabilize the voltage, but will work like a diode and malfunctions, smoke, explosions will begin ...

After checking that all components are connected correctly, the amplifier can be started.
Lanzar, like any other powerful ULF circuit, is powered by a bipolar voltage source. The input voltage rating can be from bipolar 25/30 to 75 Volts, but I don’t advise you to run it at maximum, so +/-50 Volts is the most suitable input power rating.

—————————- For the initial start-up of the circuit, you need to have a power supply at hand for the specified voltage, the power of the unit is 100 watts (although to run the amplifier at full power, you need a power supply with a power of 300-400 watts.

The transformer is connected to a 220 volt network through an incandescent lamp 220 volts 100-150 watts. The lamp serves as additional insurance, in case of malfunctions, burn fewer components. It should be noted that for the normal operation of the power amplifier after the diode rectifier, a good block of capacitors is needed, the total capacitance of all capacitors in one arm should be 10000-30000 uF, the voltage of the capacitors is preferably 100 volts (with a double margin).

We select limiting resistors for powering the differential stage based on the supply voltage according to the table below.

Power supply ±70 V - 3.3 kOhm ... 3.9 kOhm
Power supply ±60 V - 2.7 kOhm ... 3.3 kOhm
Power supply ±50 V - 2.2 kOhm ... 2.7 kOhm
Power supply ±40 V - 1.5 kOhm ... 2.2 kOhm
Power supply ±30 V - 1.0 kOhm ... 1.5 kOhm

Pick up limiting resistors with a power of 1-2 watts.
The first launch of the amplifier is done with an INPUT SHORTED TO GROUND, do not confuse ground with a minus! - ground, this is the middle point from the transformer.

For starters, there is no need for heatsinks for the terminations. We connect the transformer to the 220 Volt network, if there are no pops and special effects, then we turn off the power and check the heat dissipation on the field keys by touch, if nothing is felt, then we solder the input from the ground and play music, for starters from a mobile phone. We turn on the amplifier again, if the music plays, then everything is ok.
For maximum power the input needs to be signaled from a more powerful sound source, the car radio is just such a source.

We turn on the amplifier to music for 10-25 minutes at 40% volume, then it's time to adjust the quiescent current of the output stage, for this a photo is attached.

Thus, we have finished assembling the amplifier, you can rejoice, because this kind of amplifier costs a lot of money, in the end it is one thing to buy, but to make your own amplifier with your own hands is quite another.

Archive for the article…DOWNLOAD…

This amplifier can be ordered - [email protected]

Best regards - AKA KASYAN

High input impedance and shallow feedback are the main secret of warm tube sound. It's not a secret for anyone that it is on the tubes that the most high-quality and expensive amplifiers are realized, which belong to the HI-End category. Let's understand what a quality amplifier is? The low-frequency power amplifier has the right to be called high-quality, which completely repeats the shape of the input signal at the output, without distorting it, of course, the output signal is already amplified. On the network you can find several circuits of really high-quality amplifiers that have the right to be classified as HI-End and tube circuitry is not at all necessary. To obtain maximum quality, you need an amplifier whose output stage operates in pure class A. The maximum linearity of the circuit gives a minimum amount of distortion at the output, therefore, in the structure of high-quality amplifiers, special attention is paid to this factor. Lamp circuits are good, but not always available even for self-assembly, and industrial lamp UMZCH from branded manufacturers cost from several thousand to several tens of thousands of US dollars - this price is certainly not affordable for many.

The question arises - is it possible to achieve similar results from transistor circuits? The answer will be at the end of the article.

There are a lot of linear and super-linear low-frequency power amplifier circuits, but the circuit that will be considered today is a high-quality ultra-linear circuit, which is implemented on only 4 transistors. The circuit was created back in 1969 by British sound engineer John Linsley-Hood. The author is the creator of several more high-quality circuits, in particular class A. Some experts call this amplifier the highest quality among transistor ULFs, and I was convinced of this a year ago.

The first version of such an amplifier was presented on. A successful attempt to implement the circuit made me create a two-channel ULF according to the same scheme, assemble everything in a case and use it for personal needs.

Circuit Features

Despite its simplicity, the scheme has several features. Proper operation may be affected by improper board layout, poor component placement, improper power supply, etc.

It is the power supply that is a particularly important factor - I strongly advise against powering this amplifier from all kinds of power supplies, the best option is a battery or a power supply with a battery connected in parallel.

The power of the amplifier is 10 watts with a power supply of 16 volts into a load of 4 ohms. The circuit itself can be adapted for 4, 8 and 16 ohm heads.

I created a stereo version of the amplifier, both channels are located on the same board.

Since the original circuit transistors could not be found, analogues had to be used. The entire base is domestic. The first transistor (where the sound is actually formed) was put in germanium, it sounds better by ear. You can use any P-N-P low-power germanium transistors MP25 and the like. The transistor, if desired, can be replaced with a KT361 or no less noisy.

The second one is designed to build up the output stage, I installed KT801 (it was rather difficult to get it.

In the output stage itself, I installed powerful bipolar reverse conduction switches - KT803 got undoubtedly high sound quality with them, although I experimented with many transistors - KT805, 819, 808, even put powerful composite ones - KT827, with it the power is much higher, but the sound is not compare with KT803, although this is just my subjective opinion.

Input capacitor with a capacity of 0.1-0.33uF, you need to use film capacitors with minimal leakage, preferably from well-known manufacturers, the same with the output electrolytic capacitor.

If the circuit is designed for a load of 4 ohms, then you should not increase the supply voltage above 16-18 volts.

I decided not to install a sound regulator, it, in turn, also affects the sound, but it is advisable to put a 47k resistor in parallel with the input and minus.

The board itself is a breadboard. I had to tinker with the board for a long time, since the track lines also had some effect on the sound quality in general. This amplifier has a very wide frequency response, from 30 Hz to 1 MHz.

Setup is easy. To do this, you need a variable resistor to achieve half the supply voltage at the output. For a more precise setting, it is worth using a multi-turn variable resistor. We connect one probe of the multimeter to the minus power supply, put the other to the output line, i.e. to the plus of the electrolyte at the output, thus, slowly rotating the variable, we achieve half the power at the output.

The quiescent current of the amplifier is 0.5-0.7A and this is quite normal for class A. The efficiency of the circuit is no more than 25%, all the main power of the power supply turns into unnecessary heat, which is released by the transistors of the output stage, so they need intensive cooling, perhaps you will need a cooler.

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

Device basis

Beginning radio amateurs first of all ask themselves the question: what can a simple sound amplifier be assembled from 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

A TDA series chip and a similar one can be purchased in stores or use a chip 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 details.

transistors

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

Lamps

To date, the outdated assembly method based on tubes gives high-quality sound, but has several disadvantages:

increased energy intensity
dimensions
cost of components

Recommendations for the correct assembly of a sound amplifier with your own hands

A homemade sound quality amplification device based on TDA series chips and their analogues generates a lot of heat. For cooling, you need a radiator grill of a suitable size, depending on the model of the microcircuit itself and the power of the amplifier. In the case you need to provide a place for it.

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

We apply a serious and responsible approach to the assembly of the 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
button-switch
wires
cooling radiator
screws
hot melt and thermal paste
soldering iron and rosin

Diagrams 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, estimated final dimensions. It is assembled on a printed circuit board, which will make the device compact and more convenient. In the assembly process, you can not do without a soldering iron or soldering station.

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

The simplest and most common option for manufacturing a single-channel amplifier is to use a microcircuit, supplemented with resistors and capacitors, as the basis.

Algorithm of actions for manufacturing

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

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

run the device in test mode (detect and eliminate faults in case of occurrence)
assembly of the amplifier (connection to the power supply and other components)

Note!

Do-it-yourself home and car amplifiers

At home, powerful sound is often lacking when watching movies on a laptop or listening to music on headphones. Consider how to 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 the resistance of the windings up to 4 ohms.

Assembly accessories:

9 volt power supply
printed circuit board
chip TDA 7231
frame
non-polar capacitor 0.1 uF - 2 pcs
polar capacitor 100 uF
polar capacitor 220 uF
polar capacitor 470 uF
resistor constant 10 kΩ m 4.7 ohm
on/off switch
entry socket

Manufacturing scheme

The algorithm of assembly actions is selected depending on the selected scheme. It is necessary to take into account 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

It is possible to assemble an amplifier for a car radio on a common TDA8569Q chip. 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, in addition to the circuit, a filter against interference created by the operation of the car.

First, draw the printed circuit board, then drill holes in it. Then the board must be etched with ferric chloride. After tinning and soldering all the details of the microcircuit. The feed paths will need to be thickly soldered to avoid power additives. Provide a cooling system using a cooler or radiator grille.

At the end of the assembly, it is necessary to make a filter from the interference of the ignition system and poor sound 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 at hand all the components from which you can easily assemble a simple sound amplifier.

DIY sound amplifier photo

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