DIY amplifier for computer speakers. The simplest sound amplifier. ULF tests at home

Using a desktop computer without sound is very problematic. It’s not normal to listen to music or watch a movie. Unless with headphones, because... There is no sound amplifier for connecting external acoustics in the computer. Of course, stores in our technological age offer a variety of models of different price categories, but you can try to provide yourself with a good sound environment yourself.

Sound amplifier for computer

Let's consider one of the most simple amplifiers. Anyone who knows how to hold a soldering iron and at least a little understands the basics of physics will be able to assemble it.
The basis of the amplifier will be the TDA 1557 chip, widely used in radio stores,

Chip TDA 1557Q for computer audio amplifier

which is a bridge stereo amplifier with a simple connection circuit that can be assembled and mounted by soldering the parts directly on the legs of the microcircuit without etching the printed circuit board.

To assemble the amplifier, in addition to the microcircuit itself, you will need: 2 resistors with a resistance of 10 kOhm, 3 film capacitors, 2 of which with a capacity of 0.22 - 0.47 μF (220n -470n) and one 0.1 μF (100n), an electrolytic capacitor with a capacity of 2,200 - 10,000 μF with an operating voltage of at least 16 V and a button or toggle switch to turn the amplifier on and off. The cost of all parts for assembly varies from $10 to $15 or 400 - 600 rubles. You will also need some shielded wire and speakers or speakers with a power of 15 - 30 W, a resistance of 4 - 8 Ohms. The installation diagram is clearly presented below.

Amplifier connection diagram for TDA1557Q

Sound to the amplifier must be supplied from the headphone output of the computer sound card using a shielded wire to avoid background noise and extraneous noise from the speakers. Solder the electrolytic capacitor with the shortest possible wires. The level of voltage drop during power peaks depends on the size of its capacity, hence the depth and purity of the bass. It is recommended to set at least 2,200 µF. The upper limit on capacity is not limited.
You can solder a 0.1 µF film capacitor directly to the legs of this capacitor. The toggle switch is used to smoothly turn on the amplifier so that there is no click in the speakers when power is applied and the volume is muted or the amplifier sleeps.
The amplifier operates at a voltage of 10 - 18 V, therefore, you can connect it from the computer power supply from the +12V output and ground COM.

Do-it-yourself sound amplifier for a computer

I had a four-watt burnt-out speaker lying around. The body is quite beautiful, and most importantly, it is made of thick plastic, which is excellent for some kind of amateur radio design. Having disassembled the column and removed the unnecessary speaker, I removed the coil, biting out the extra partitions with wire cutters. I cut out the top and painted the cardboard while the paint was drying and started assembling it. amplifier on tda 7294, which can be purchased at any radio store.

Amplifier circuit:

After drawing the amplifier circuit and making holes for the parts, I inserted everything necessary and placed 7294 separately on the wires. I placed the microcircuit on a small radiator from the P210 transistor, spreading more KTP heat-conducting paste.

I turned on the circuit - it worked immediately, despite the fact that this was the first time I assembled an amplifier using the TDA7294! And also, encouraged by success, I decided to assemble a signal level indicator, and since I didn’t have a textolite, I also assembled it on cardboard, soldering it into two channels, and there was only one microcircuit

I decided to assemble the second channel later, when I bought a microcircuit.

The sound level indicator was powered by 12 volts, and the power amplifier by 32 volts.

I didn’t want to rewind the power transformer (so that it wouldn’t start humming after disassembly), so I installed another one at 12 volts. The radiator was noticeably warm, so I installed a cooler from the computer and powered it from 12 volts.

Later I also assembled bass and treble controls, but they greatly reduced the signal, so I simplified the design of the tone block by installing a regular switch for bridging the high frequencies. I attached the speaker outputs to the side of the case.

At some point, I finally got tired of the weak sound from plastic 10-watt computer speakers and wanted really high power, and of course better bass! Buying 100 watt active speakers is not a problem - the problem is finding 10,000 rubles for such a thing. But you can get by with an amount 10 times less if you assemble the electronics yourself and find passive speakers of suitable power.

UMZCH electrical circuit

The electronics of computer speakers consists of several systems:

• The end is an audio power amplifier with 2 x TDA7294.
• Preamplifier on the TL072 chip.
• Signal input selector using touch button and CD4017+ relay.
• Bluetooth module from a Chinese set.
• Switching on/off using the same touch button on CD4017 + relay
• Cooling system with thermal control on a field MOSFET.

Here we present only the most basic circuit - a stereo low-frequency amplifier block. The remaining modules have no special features and are made according to standard designs, which are not a problem to find. Or exclude it altogether, since the main thing is the amplifier itself on the TDA7294.

Amplifier housing

The body was created from boards and MDF. In general, the design of this amplifier is a problem for those who want to perform mechanical work at home - it is not easy to find necessary materials and equipment. But if you’re not lucky enough to find a suitable box, then we don’t think it’s a problem for anyone to put it together from MDF.

ULF tests at home

There is no need for a subwoofer here - with good power and large low-frequency speakers in the speakers, the bass will be enough. As a result, with this design it was possible to obtain 2 x 60 watts of power, and this was not at the limit (so that there was less distortion). So everyone is happy with the sound, including the neighbors!

In this article we will talk about amplifiers. They are also ULF (low frequency amplifiers), they are also UMZCH (power amplifiers) audio frequency). These devices can be made on both transistors and microcircuits. Although some radio amateurs, paying tribute to the vintage fashion, make them the old fashioned way - using lamps. We recommend you look here. I would like to draw special attention of beginners to microcircuits car amplifiers with 12 volt power supply. Using them you can get quite high quality sound at the exit, and for assembly, knowledge of a school physics course is practically enough. Sometimes from the body kit, or in other words, those parts on the diagram without which the microcircuit will not work, there are literally 5 pieces on the diagram. One of these, an amplifier on a chip TDA1557Q shown in the figure:

Such an amplifier was assembled by me at one time; I have been using it for several years together with Soviet 8 Ohm 8 W acoustics, together with a computer. The sound quality is much higher than that of Chinese plastic speakers. True, in order to feel a significant difference, I had to buy a creative sound card; the difference with the built-in sound was insignificant.

The amplifier can be assembled by hanging mounting

The amplifier can also be assembled by hanging mounting, directly on the terminals of the parts, but I would not recommend assembling using this method. It’s better to spend a little more time, find a wired printed circuit board (or wire it yourself), transfer the design to the PCB, etch it and end up with an amplifier that will work for many years. All these technologies have been described many times on the Internet, so I will not dwell on them in more detail.

Amplifier attached to radiator

I’ll say right away that amplifier chips get very hot during operation and need to be secured by applying thermal paste to the radiator. For those who just want to assemble one amplifier and do not have the time or desire to study programs for PCB layout, LUT technologies and etching, I can suggest using special development boards with holes for soldering. One of them is shown in the photo below:

As you can see in the photo, connections are not made by tracks on printed circuit board, as in the case of printed wiring, but with flexible wires soldered to the contacts on the board. The only problem when assembling such amplifiers is the power supply, which produces a voltage of 12-16 volts, with a current consumption by the amplifier of up to 5 amperes. Of course, such a transformer (5 amperes) will have rather large dimensions, so some people use pulsed sources nutrition.

Transformer for amplifier - photo

I think many people at home have computer power supplies that are now obsolete and are no longer used as part of system units, but such power supplies are capable of delivering +12 volts through circuits, currents much greater than 4 amperes. Of course, such power supply among sound connoisseurs is considered worse than a standard transformer one, but I connected a switching power supply to power my amplifier, then changed it to a transformer one - the difference in sound can be said to be imperceptible.

After leaving the transformer, of course, you need to install a diode bridge to rectify the current, which must be designed to work with the large currents consumed by the amplifier.

After the diode bridge there is a filter on an electrolytic capacitor, which should be designed for a noticeably higher voltage than in our circuit. For example, if we have a 16 volt power supply in the circuit, the capacitor should be 25 volts. Moreover, this capacitor should be as large as possible; I have 2 capacitors of 2200 μF connected in parallel, and this is not the limit. In parallel with the power supply (bypass), you need to connect a ceramic capacitor with a capacity of 100 nf. At the input of the amplifier, film decoupling capacitors with a capacity of 0.22 to 1 µF are installed.

Film capacitors

Connecting the signal to the amplifier, in order to reduce the level of induced interference, should be done with a shielded cable; for these purposes it is convenient to use a cable Jack 3.5- 2 Tulips, with corresponding sockets on the amplifier.

Cable jack 3.5 - 2 tulips

The signal level (volume on the amplifier) ​​is adjusted using a potentiometer, if the amplifier is stereo, then dual. The connection diagram for the variable resistor is shown in the figure below:

Of course, amplifiers can also be made using transistors, while power supply, connection and volume control are used in them in exactly the same way as in amplifiers on microcircuits. Consider, for example, an amplifier circuit using a single transistor:

There is also a separating capacitor here, and the minus of the signal is connected to the minus of the power supply. Below is a diagram of a push-pull power amplifier with two transistors:

The following circuit also uses two transistors, but is assembled from two stages. Indeed, if you look closely, it seems to consist of 2 almost identical parts. Our first cascade includes: C1, R1, R2, V1. In the second stage C2, R3, V2, and the load headphones B1.

Two-stage transistor amplifier - circuit diagram

If we want to make a stereo amplifier, we will need to assemble two identical channels. In the same way, we can, by assembling two circuits of any mono amplifier, turn it into stereo. Below is a diagram of a three-stage transistor power amplifier:

Three-stage transistor amplifier - circuit diagram

Amplifier circuits also differ in supply voltage, some require 3-5 volts to operate, others require 20 or more. Some amplifiers require bipolar power to operate. Below are 2 amplifier circuits on a chip TDA2822, first stereo connection:

In the diagram, speaker connections are indicated in the form of resistors RL. The amplifier operates normally at 4 volts. The following figure shows a bridged circuit that uses one speaker, but produces more power than the stereo version:

The following figure shows the amplifier circuits, both circuits are taken from the datasheet. Power supply 18 volts, power 14 watts:

The acoustics connected to the amplifier may have different resistance, most often it is 4-8 Ohms, sometimes there are speakers with a resistance of 16 Ohms. You can find out the speaker resistance by turning it over back side to itself, the rated power and resistance of the speaker are usually written there. In our case it is 8 ohms, 15 watts.

If the speaker is inside the column and there is no way to see what is written on it, then the speaker can be ringed with a tester in ohmmeter mode by selecting a measurement limit of 200 Ohms.

Speakers have polarity. The cables that connect the speakers are usually marked in red, for the wire that is connected to the positive of the speaker.

If the wires are not marked, you can check the correct connection by connecting the battery plus with plus, minus with minus of the speaker (conditionally), if the speaker cone moves out, then we guessed the polarity. More variety ULF circuits, including lamp ones, can be viewed at. We think the most large selection schemes on the Internet.

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 using TDA chip 7294. 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 detailed diagrams in 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