Amplifier circuits on tda. A very simple powerful amplifier on a chip

Full ULF 2x70 Watt on TDA7294.

When assembling an amplifier on microcircuits, the TDA7294 is not a bad choice. Well, however, we will not dwell on the technical characteristics, you can see them in the PDF file TDA7294_datasheet, located in the folder for downloading material for assembling this ULF. As you already understood from the title of the article, this is a complete amplifier circuit that contains a power supply, signal pre-amplification stages with a three-band tone control, implemented on two common 4558 operational amplifiers, two channels of final stages, as well as a protection unit. The circuit diagram is shown below:

With a supply voltage of ±35 Volts into an 8 Ohm load, you get 70 Watts of power.

The PCB sources are as follows:

PCB LAY6 format:

Arrangement of elements on the amplifier board:

Photo view of LAY board format:

The board has a J5 connector for connecting a temperature sensor (Bimetal Thermostat), designated B60-70. In normal mode, its contacts are open; when heated to 60°C, the contacts close and the relay turns off the load. In principle, you can also use thermal sensors with normally closed contacts designed to operate at 60...70°C, but you need to connect it to the gap between the emitter of transistor Q6 and the common wire, while connector J5 is not used. If you are not going to use this function, leave connector J5 empty.

Operational amplifiers are installed in sockets. Relay with an operating voltage of 12 Volts with two groups of switching contacts, the contacts must withstand 5 Amps.

Printed circuit board for LAY6 fuses:

Photo view of the LAY format of the fuse board:

The power connector for the protection unit is located on the board just above connector J5. Just make a jumper with two wires between this connector and the main power connector as shown in the picture below:

External connections:

Additional Information:

4Ohm – 2x18V 50Hz
8Ohm – 2x24V 50Hz

With a power supply of 2x18V 50Hz:

Resistors R1, R2 – 1 kOhm 2W
Resistor RES – 150 Ohm 2W

With a power supply of 2x24V 50Hz:

Resistors R1, R2 – 1.5 kOhm 2W
Resistor RES – 300 Ohm 2W

The JRC4558 operational amplifier can be replaced with NE5532 or TL072.

Please note that on the conductor side of the printed circuit board, an LL4148 diode in SMD version is installed between the contacts of the relay coil; you can solder a regular 1N4148.

There is a GND point on the board near the volume control; it is intended for grounding the housings of all controllers. This piece of bare copper wire is clearly visible in the main picture of the news.

List of elements for repeating the amplifier circuit on the TDA7293 (TDA7294):

Electrolytic capacitors:

10000mF/50V – 2 pcs.
100mF/50-63V – 9 pcs.
22mF – 5 pcs.
10mF – 6 pcs.
47mF – 2 pcs.
2.2mF – 2 pcs.

Film capacitors:

1 mF – 8 pcs.
100n – 8 pcs.
6n8 – 2 pcs.
4n7 – 2 pcs.
22n – 2 pcs.
47n – 2 pcs.
100pF – 2 pcs.
47pF – 4 pcs.

Resistors 0.25W:

220R – 1 pc.
680R – 2 pcs.
1K – 6 pcs.
1K5 – 2 pcs.
3K9 – 4 pcs.
10K – 10 pcs.
20K – 2 pcs.
22K – 8 pcs.
30K – 2 pcs.
47K – 4 pcs.
220K – 3 pcs.

Resistors 0.5W:

2W resistors:

RES - 300R – 2 pcs.
100R – 2 pcs.

Diodes:

Zener diodes 12V 1W – 2 pcs.
1n4148 – 1 pc.
LL4148 – 1 pc.
1n4007 – 3 pcs.
Bridge 8...10A – 1 pc.

Variable resistors:

A50K – 1 pc.
B50K – 3 pcs.

Chips:

NE5532 – 2 pcs.
TDA7293 (TDA7294) – 2 pcs.

Connectors:

3x – 1 pc.
2x – 2 pcs.

Relay – 1 pc.

Transistors:

BC547 – 5 pcs.
LM7812 – 1 pc.

You can download the circuit diagram of the amplifier for TDA7294, TDA7294_datasheet, printed circuit boards in LAY6 format in one file from our website. Archive size – 4 Mb.

This article will discuss a fairly common and popular amplifier chip TDA7294. Let's look at its brief description, technical characteristics, typical connection diagrams and give a diagram of an amplifier with a printed circuit board.

Description of the TDA7294 chip

The TDA7294 chip is a monolithic integrated circuit in a MULTIWATT15 package. It is intended for use as an AB Hi-Fi audio amplifier. Thanks to its wide supply voltage range and high output current, the TDA7294 is capable of delivering high output power into 4 ohm and 8 ohm speaker impedances.

The TDA7294 has low noise, low distortion, good ripple rejection, and can operate from a wide range of supply voltages. The chip has built-in short circuit protection and an overheat shutdown circuit. The built-in Mute function makes it easy to control the amplifier remotely, preventing noise.

This integrated amplifier is easy to use and does not require many external components to function properly.

TDA7294 Specifications

Chip dimensions:

As stated above, chip TDA7294 is produced in the MULTIWATT15 housing and has the following pinout arrangement:

1. GND (common wire)
2. Inverting Input
3. Non Inverting Input
4. In+Mute
5. N.C. (not used)
6. Bootstrap
7. Stand-by
8. N.C. (not used)
9. N.C. (not used)
10. +Vs (plus power)
11. Out
12. -Vs (minus power)

You should pay attention to the fact that the microcircuit body is connected not to the common power line, but to the power supply minus (pin 15)

Typical TDA7294 connection diagram from datasheet

Bridge connection diagram

Bridged connection is the connection of an amplifier to speakers, in which the channels of a stereo amplifier operate in the mode of monoblock power amplifiers. They amplify the same signal, but in antiphase. In this case, the speaker is connected between the two outputs of the amplification channels. Bridge connection allows you to significantly increase the power of the amplifier

In fact, this bridge circuit from the datasheet is nothing more than two simple amplifiers to the outputs to which an audio speaker is connected. This connection circuit can only be used with speaker impedances of 8 Ohms or 16 Ohms. With a 4 ohm speaker, there is a high probability of the chip failing.

Among integrated power amplifiers, the TDA7294 is a direct competitor to the LM3886.

Example of using TDA7294

This is a simple 70 watt amplifier circuit. Capacitors must be rated for at least 50 volts. For normal operation of the circuit, the TDA7294 chip must be installed on a radiator with an area of ​​about 500 cm2. The installation is carried out on a single-sided board made according to .

Printed circuit board and arrangement of elements on it:

Amplifier power supply TDA7294

To power an amplifier with a 4 Ohm load, the power supply must be 27 volts; with a speaker impedance of 8 Ohms, the voltage should already be 35 volts.

The power supply for the TDA7294 amplifier consists of a step-down transformer Tr1 having a secondary winding of 40 volts (50 volts with a load of 8 Ohms) with a tap in the middle or two windings of 20 volts (25 volts with a load of 8 Ohms) with a load current of up to 4 amperes. The diode bridge must meet the following requirements: forward current of at least 20 amperes and reverse voltage of at least 100 volts. The diode bridge can be successfully replaced with four rectifier diodes with the corresponding indicators.

Electrolytic filter capacitors C3 and C4 are designed mainly to remove the peak load of the amplifier and eliminate voltage ripple coming from the rectifier bridge. These capacitors have a capacity of 10,000 microfarads with an operating voltage of at least 50 volts. Non-polar capacitors (film) C1 and C2 can have a capacity of 0.5 to 4 µF with a supply voltage of at least 50 volts.

Voltage distortions should not be allowed; the voltage in both arms of the rectifier must be equal.

(1.2 Mb, downloaded: 4,035)

The article is dedicated to lovers of loud and high-quality music. TDA7294 (TDA7293) is a low-frequency amplifier microcircuit manufactured by the French company THOMSON. The circuit contains field-effect transistors, which ensures high sound quality and soft sound. A simple circuit with few additional elements makes the circuit accessible to any radio amateur. A correctly assembled amplifier from serviceable parts begins to work immediately and does not require adjustment.

The audio power amplifier on the TDA 7294 chip differs from other amplifiers of this class:

• high output power,
• wide supply voltage range,
• low percentage of harmonic distortion,
• "soft sound,
• few “attached” parts,
• low cost.

Can be used in amateur radio audio devices, when modifying amplifiers, speaker systems, audio equipment, etc.

The picture below shows typical circuit diagram power amplifier for one channel.

The TDA7294 microcircuit is a powerful operational amplifier, the gain of which is set by a negative feedback circuit connected between its output (pin 14 of the microcircuit) and the inversion input (pin 2 of the microcircuit). The direct signal is supplied to the input (pin 3 of the microcircuit). The circuit consists of resistors R1 and capacitor C1. By changing the values ​​of resistance R1, you can adjust the sensitivity of the amplifier to the parameters of the pre-amplifier.

Technical characteristics of the TDA7294 chip

Technical characteristics of the TDA7293 chip

To assemble this amplifier you will need the following parts:

1. Chip TDA7294 (or TDA7293)
   2. Resistors with a power of 0.25 watt
   R1 – 680 Ohm
   R2, R3, R4 – 22 kOm
   R5 – 10 kOhm
   R6 – 47 kOhm
   R7 – 15 kOhm
   3. Film capacitor, polypropylene:
   C1 – 0.74 mkF
   4. Electrolytic capacitors:
   C2, C3, C4 – 22 mkF 50 volt
   C5 – 47 mkF 50 volt
   5. Double variable resistor - 50 kOm

A mono amplifier can be assembled on one chip. To assemble a stereo amplifier, you need to make two boards. To do this, we multiply all the necessary parts by two, except for the dual variable resistor and power supply. But more on that later.

The circuit elements are mounted on a printed circuit board made of single-sided foil fiberglass.

A similar circuit, but with a few more elements, mainly capacitors. The switch-on delay circuit at the “mute” pin 10 input is enabled. This is done for a soft, pop-free turn on of the amplifier.

A microcircuit is installed on the board, from which unused pins have been removed: 5, 11 and 12. Install using a wire with a cross-section of at least 0.74 mm2. The chip itself must be installed on a radiator with an area of ​​at least 600 cm2. The radiator should not touch the amplifier body in such a way as there will be a negative supply voltage on it. The housing itself must be connected to a common wire.

If you use a smaller radiator area, you need to make forced airflow by placing a fan in the amplifier case. The fan is suitable from a computer with a voltage of 12 volts. The microcircuit itself should be attached to the radiator using heat-conducting paste. Do not connect the radiator to live parts, except for the negative power bus. As mentioned above, the metal plate at the back of the microcircuit is connected to the negative power circuit.

Chips for both channels can be installed on one common radiator.

The power supply is a step-down transformer with two windings with a voltage of 25 volts and a current of at least 5 amperes. The voltage on the windings should be the same and so should the filter capacitors.

Voltage imbalance should not be allowed. When supplying bipolar power to the amplifier, it must be supplied simultaneously!

It is better to install ultra-fast diodes in the rectifier, but in principle, ordinary ones like D242-246 with a current of at least 10A are also suitable. It is advisable to solder a capacitor with a capacity of 0.01 μF in parallel to each diode. You can also use ready-made diode bridges with the same current parameters.

Filter capacitors C1 and C3 have a capacity of 22,000 microfarads at a voltage of 50 volts, capacitors C2 and C4 have a capacity of 0.1 microfarads.

The supply voltage of 35 volts should only be with a load of 8 ohms; if you have a load of 4 ohms, then the supply voltage must be reduced to 27 volts. In this case, the voltage on the secondary windings of the transformer should be 20 volts.

You can use two identical transformers with a power of 240 watts each. One of them serves to obtain positive voltage, the second - negative. The power of the two transformers is 480 watts, which is quite suitable for an amplifier with an output power of 2 x 100 watts.

Transformers TBS 024 220-24 can be replaced with any others with a power of at least 200 watts each. As written above, the nutrition should be the same - transformers must be the same!!! The voltage on the secondary winding of each transformer is from 24 to 29 volts.

Amplifier circuit increased power on two TDA7294 chips in a bridge circuit.

According to this scheme, for the stereo version you will need four microcircuits.

Amplifier specifications:

• Maximum output power at 8 Ohm load (supply +/- 25V) - 150 W;
• Maximum output power at a load of 16 Ohms (supply +/- 35V) - 170 W;
• Load resistance: 8 - 16 Ohm;
• Coef. harmonic distortion, at max. power 150 watts, e.g. 25V, heating 8 Ohm, frequency 1 kHz - 10%;
• Coef. harmonic distortion, at a power of 10-100 watts, for example. 25V, heating 8 Ohm, frequency 1 kHz - 0.01%;
• Coef. harmonic distortion, at a power of 10-120 watts, for example. 35V, heating 16 Ohm, frequency 1 kHz - 0.006%;
• Frequency range (with a non-frequency response of 1 db) - 50Hz ... 100kHz.

View of the finished amplifier in a wooden case with a transparent plexiglass top cover.

For the amplifier to operate at full power, you need to apply the required signal level to the input of the microcircuit, and this is at least 750 mV. If the signal is not enough, then you need to assemble a pre-amplifier for boosting.

Setting up the amplifier

A properly assembled amplifier does not need adjustment, but no one guarantees that all parts are absolutely in good working order; you need to be careful when turning it on for the first time.

The first switch-on is carried out without load and with the input signal source turned off (it is better to short-circuit the input with a jumper). It would be nice to include fuses of about 1A in the power circuit (both in the plus and minus between the power source and the amplifier itself). Briefly (~0.5 sec.) Apply the supply voltage and make sure that the current consumed from the source is small - the fuses do not burn out. It is convenient if the source has LED indicators - when disconnected from the network, the LEDs continue to light for at least 20 seconds: the filter capacitors are discharged for a long time by the small quiescent current of the microcircuit.

If the current consumed by the microcircuit is large (more than 300 mA), then there can be many reasons: short circuit in installation; poor contact in the “ground” wire from the source; “plus” and “minus” are confused; the pins of the microcircuit touch the jumper; microcircuit is faulty; capacitors C11, C13 are soldered incorrectly; capacitors C10-C13 are faulty.

Having made sure that everything is normal with the quiescent current, we safely turn on the power and measure the constant voltage at the output. Its value should not exceed +-0.05 V. High voltage indicates problems with C3 (less often with C4), or with the microcircuit. There have been cases when the “ground-to-ground” resistor was either poorly soldered or had a resistance of 3 kOhms instead of 3 ohms. At the same time, the output was constant 10...20 volts.

By connecting an AC voltmeter to the output, we make sure that the AC voltage at the output is zero (this is best done with the input closed, or simply with the input cable not connected, otherwise there will be noise at the output). The presence of alternating voltage at the output indicates problems with the microcircuit, or circuits C7R9, C3R3R4, R10.

Unfortunately, conventional testers often cannot measure the high-frequency voltage that appears during self-excitation (up to 100 kHz), so it is best to use an oscilloscope here.

All! You can enjoy your favorite music!

The amplifier circuit on the TDA2030 is the simplest and highest quality amplifier that even a schoolchild can replicate.

Description of the TDA2030A chip

In the role of an amplifier microcircuit in this article, we will take the TDA2030A microcircuit, which can be bought in absolutely any radio store at a price no more expensive than a loaf of black bread.

TDA2030A is a chip that is executed by Pentawatt (a package with five pins for power linear integrated circuits). It is mainly used as a low frequency amplifier (LF) in the AB amplification class. The maximum single-polar supply is 44 Volts. It is unlikely that you will find this voltage in your home laboratory. Therefore, using this chip is quite suitable for your electronic trinkets without the harm of burning the chip.

The TDA2030A also has high output current up to 3.5 Amps peak and has low harmonic and crossover distortion. This means that an amplifier assembled on this chip will have a very good sound. In addition, the chip includes protection against and automatically limits power dissipation. Overheat protection is also included, in which the chip automatically turns off when the case heats up too much.

P.S. Since the market is mostly flooded with Chinese TDAs, it is possible that these protections may not work as expected, or may not work at all. Therefore, I do not recommend checking them for short circuits and overheating.

The simplest amplifier circuit on TDA2030A

As you can see, there is nothing complicated here. When assembling the circuit, do not forget about electrolytic ones, which have polarity and maximum voltage. As you remember, it should not exceed +Upit. +Up in this circuit you can take from 12 to 44 Volts.

Powerful amplifier circuit on TDA2030A

If you wish, you can assemble a circuit with a pair of complementary transistors, thereby increasing the output power. In other words, your speaker will scream even louder, if it is, of course, designed for such power. The scheme is no more complicated than the previous one:

If you do not find foreign transistors BD907 and BD908, then they can be replaced with domestic analogues KT819 and KT818, respectively.

All of the above proposed schemes amplify only one channel. To amplify the stereo signal, we will need to make another similar amplifier. Also, do not forget about radiators, since at high power the microcircuit gets very hot.

Conclusion

I have been collecting these circuits for a long time and have become convinced of their functionality. Although the bear stepped on my ear, I can say for sure that the sound quality of such amplifiers is in no way inferior to some fancy Hi-Fi amplifiers. It would be perfect for a small room or a medium-sized garage to dance to your favorite songs.

You can also find all these circuits in the datasheet for the chip. You can download the datasheet from the link, or easily find it on the Internet.

Where to buy an amplifier

Aliexpress even has a ready-made simplified amplifier circuit

You can watch it at this link.

If you don’t want to bother with soldering amplifiers at all, then you can purchase ready-made modules, which will be several times cheaper than ready-made amplifiers in a housing

The TDA7294 microcircuit is an integrated low-frequency amplifier, which is very popular among electronics engineers, both beginners and professionals. The network is full of different reviews about this chip. I decided to build an amplifier on it. I took the diagram from the datasheet.

This “micruha” feeds on a bipolar diet. For beginners, I will explain that it is not enough to have a “plus” and a “minus”.

You need a source with a positive terminal, a negative terminal and a common one. For example, relative to the common wire there should be plus 30 Volts, and in the other arm minus 30 Volts.

The amplifier on the TDA7294 is quite powerful. The maximum rated power is 100 W, but this is with nonlinear distortion of 10% and at maximum voltage (depending on load resistance). You can reliably shoot at 70W. Thus, on my birthday, I listened to two parallel-connected “Radio Engineering S30” speakers on one TDA 7294 channel. The entire evening and half of the night, the speakers sounded, sometimes putting them into overload. But the amplifier withstood it calmly, although it sometimes overheated (due to poor cooling).

Main characteristicsTDA7294

Supply voltage +-10V…+-40V

Peak output current up to 10A

Operating temperature of the crystal up to 150 degrees Celsius

Output power at d=0.5%:

At +-35V and R=8Ohm 70W

At +-31V and R=6Ohm 70W

At +-27V and R=4Ohm 70W

With d=10% and increased voltage (see), you can achieve 100W, but it will be a dirty 100W.

Amplifier circuit for TDA7294

The diagram shown is taken from the passport, all denominations are preserved. With proper installation and correctly selected element values, the amplifier starts the first time and does not require any settings.

Amplifier elements

The values ​​of all elements are indicated in the diagram. Resistor power 0.25 W.

The “microphone” itself should be installed on the radiator. If the radiator is in contact with other metal elements of the case, or the case itself is the radiator, then it is necessary to install a dielectric gasket between the radiator and the TDA7294 case.

The gasket can be silicone or mica.

The radiator area should be at least 500 sq.cm, the larger the better.

Initially, I assembled two channels of the amplifier, since the power supply allowed, but I didn’t choose the right housing and both channels simply did not fit into the housing in terms of dimensions. I tried to make the PCB smaller, but it didn't work.

After fully assembling the amplifier, I realized that the case was not enough to cool one channel of the amplifier. My case was a radiator. In short, I rolled out the lip into two channels.

When listening to my device at full volume, the crystal began to overheat, but I lowered the volume level and continued testing. As a result, I listened to music at a moderate volume until midnight, periodically causing the amplifier to overheat. The TDA7294 amplifier turned out to be very reliable.

ModeSTAND- BY TDA7294

If 3.5V or more is applied to the 9th leg, the microcircuit exits sleep mode; if less than 1.5V is applied, it will enter sleep mode.

In order to wake the device from sleep mode, you need to connect the 9th leg through a 22 kOhm resistor to the positive terminal (bipolar power supply).

And if the 9th leg is connected through the same resistor to the GND terminal (bipolar power source), then the device will enter sleep mode.

The printed circuit board located under the article is routed so that leg 9 is connected via a 22 kOhm resistor to the positive terminal of the power supply. Consequently, when the power source is turned on, the amplifier immediately begins to operate in sleep mode.

ModeMUTE TDA7294

If 3.5V or more is applied to the 10th leg of the TDA7294, the device will exit the muting mode. If you apply less than 1.5V, the device will enter muting mode.

In practice, this is done like this: through a 10 kOhm resistor, connect the 10 leg of the microcircuit to the plus of a bipolar power source. The amplifier will “sing”, that is, it will not be muted. On the printed circuit board attached to the article, this is done using a track. When power is applied to the amplifier, it immediately begins to sing, without any jumpers or toggle switches.

If we connect the TDA7294 leg through a 10 kOhm resistor 10 to the GND pin of the power supply, then our “amplifier” will enter mute mode.

Power supply.

The voltage source for the device was an assembled one, which showed itself very well. When listening to one channel, the keys are warm. Schottky diodes are also warm, although there are no radiators installed on them. IIP without protection and soft start.

The circuit of this SMPS is criticized by many, but it is very easy to assemble. It works reliably without soft start. This circuit is very suitable for novice electronics engineers because of its prostate.

Frame.

The case was purchased.