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old friend better than the new two!
Proverb

Thanks to its small number of wiring elements, the TDA2822M integrated circuit is one of the simple amplifiers, which can be assembled in a short time, connected to an MP3 player, laptop, radio - and immediately evaluate the result of your work.

This is how attractive the description looks:
“TDA2822M is a stereo, two-channel low-voltage amplifier for portable equipment, etc.
It can be bridged, used as a headphone or control amplifier, and much more.
Operating supply voltage: 1.8 V to 12 V, power up to 1 W per channel, distortion up to 0.2%. No radiator required.
Despite its super-miniature size, it produces honest bass. The ideal chip for beginners' inhumane experiences."

With my article, I tried to help fellow radio amateurs make experiments with this interesting chip more conscious and humane.

Let's look at the chip housing

There are two microcircuits: one TDA2822, the other with the index “M” - TDA2822M.
Integral chip TDA2822(Philips) designed to create simple power amplifiers audio frequency. The permissible range of supply voltages is 3…15 V; at Upit=6 V, Rн=4 Ohm output power is up to 0.65 W per channel, in the frequency band 30 Hz...18 kHz. Powerdip 16 chip package.
Chip TDA2822M it is made in a different Minidip 8 package and has a different pinout with a slightly lower maximum power dissipation (1 W versus 1.25 W for the TDA2822).

Please note that there are no other built-in protection circuits for the output stage, which is done for reasons of better use of the power supply, unfortunately at the expense of reliability.

Pins 5 and 8 of the microcircuit are connected to the common wire via alternating current. In this case, the gain of the amplifier with a negative feedback will be:

Ku=20lg(1+R1/R2)= 20lg(1+R5/R4)=39 dB.

Structural scheme The IC is shown in Fig. 2.

Rice. 2. Block diagram of TDA2822M

It was experimentally determined that the sum of the resistances of resistors R1+R2 and R5+R4 is equal to 51.575 kOhm. Knowing the gain, it is easy to calculate that R1=R5=51 kOhm, and R2=R4=0.575 kOhm.

To reduce the gain of an OOS microcircuit, an additional resistor is usually connected in series with R2 (R4). In this case, such a circuitry technique is “interfered” with open transistor switches on transistors Q12 (Q13).

But even if we assume that the keys do not affect the feedback gain, the maneuver to reduce the gain is insignificant - no more than 3 dB; otherwise, the stability of the amplifier covered by OOS is not guaranteed.

Therefore, you can experiment with changing the transmission coefficient of the amplifier, taking into account that the resistance of the additional resistor lies in the range of 100...240 Ohms.

Rice. 3. Schematic diagram of an experimental stereo amplifier

The amplifier has the following characteristics:
Supply voltage Up=1.8…12 V
Output voltage Uout=2…4 V
Current consumption in quiescent mode Io=6…12 mA
Output power Pout=0.45…1.7 W
Gain Ku=36…41 (39) dB
Input resistance Rin=9.0 kOhm
Crosstalk attenuation between channels is 50 dB.

From a practical point of view, for reliable operation of the amplifier, it is advisable to set the supply voltage to no more than 9 V; in this case, for a load Rн=8 Ohm the output power will be 2x1.0 W, for Rн=16 Ohm - 2x0.6 W and for Rн=32 Ohm - 2x0.3 W. With load resistance Rн=4 Ohm, the optimal supply voltage will be up to 6 V (Pout=2x0.65 W).

The gain of the microcircuit of 39 dB, even taking into account a small downward adjustment by resistors R5, R6, turns out to be excessive for modern signal sources with a voltage of 250...750 mV. For example, for Up=9 V, Rн=8 Ohm, the sensitivity from the input is about 30 mV.

In Fig. 4, and the amplifier connection diagram is shown, allowing you to connect Personal Computer, MP3 player or radio with a signal level of about 350 mV. For devices with an output signal of 250 mV, the resistance of resistors R1, R2 must be reduced to 33 kOhm; at an output signal level of 0.5 V, resistors R1=R2=68 kOhm, 0.75 V – 110 kOhm should be installed.

Double resistor R3 sets the required volume level. Capacitors C1, C2 are transitional.

Rice. 4. UMZCH connection diagram: a) - to speaker systems, b) - to headphones (headphones)

In Fig. 4, b shows the connection to the amplifier of the headphone jack. Resistors R4, R5 eliminate clicks when connecting stereo phones, resistors R6, R7 limit the volume level.

During the experiments, I tried to power the UMZCH both from a stabilized power supply (on an integrated circuit and a BD912 transistor), Fig. 5, and from a battery with a capacity of 7.2 Ah for a voltage of 12 V with a power supply for fixed voltages, Fig. 6.

The supply voltage is supplied by as short a pair of wires as possible, twisted together.
A correctly assembled device does not require adjustment.

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Rice. 5. Schematic diagram of a stabilized power supply

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Rice. 6. Accumulator battery– laboratory power supply

A subjective assessment of the noise level showed that when the volume control was set to maximum level the noise is barely noticeable.
Subjective assessment of sound reproduction quality was made without comparison with the standard. The result is a good sound, listening to soundtracks does not cause irritation.

I checked the chip forums on the Internet, where I came across many messages about searching for unknown sources of noise, self-excitation and other troubles.
As a result, I developed printed circuit board, distinctive feature which is the “star” grounding of the elements. A photo view of the printed circuit board from the Sprint-Layout program is shown in Fig. 7.

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Rice. 7. Placement of parts on the experimental printed circuit board

During experiments on this signet, it was not possible to encounter any of the artifacts described on the forums.

Details of the stereo UMZCH on the TDA2822M chip
The printed circuit board is designed for installation of the most common parts: MLT, S2-33, S1-4 or imported resistors with a power of 0.125 or 0.25 W, film capacitors K73-17, K73-24 or imported MKT, imported oxide capacitors.

I used inexpensive but reliable electrolytic capacitors with low impedance, long service life (5000 hours) and the ability to operate at temperatures up to +105°C from Hitano ESX, EHR and EXR series. It should be remembered that the larger the outer diameter of the capacitor in the series, the longer its service life.

The DA1 chip is installed in an eight-pin socket. The TDA2822M chip can be replaced with KA2209B (Samsung) or K174UN34 (Angstrem OJSC, Zelenograd). CHIP capacitor C8 (SMD) is located on the side of the printed tracks.

R5, R6 - Res.-0.25-160 Ohm (Brown, blue, brown, golden) - 2 pcs.,

C3 - C5 - Cond. 1000/16V 1021+105°C - 3 pcs.,
C6, C7 - Cond. 0.1/63V K73-17 - 2 pcs.,
C8 - Cond.0805 0.1µF X7R smd – 1 pc.

Many radio amateurs, not without reason, believe that it is best to include microcircuits in accordance with the Datasheet and use printed circuit boards offered by the developers.
Below are diagrams and printed circuit boards made on the basis of the documentation with the only modification - to increase the stability of the amplifier, a film capacitor is connected in parallel with the oxide capacitor along the power supply circuit (Fig. 8, 9).

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Rice. 8. Typical circuit diagram for connecting a microcircuit in stereo mode

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Rice. 9. Placement of elements of a typical stereo UMZCH

Details of a typical stereo UMZCH
When installing elements on a printed circuit board, I advise you to use simple technological techniques described in the Datagor article.

DA1 - TDA2822M ST Housing: DIP8-300 - 1 pc.,
SCS-8 Narrow dip socket - 1 pc.,
R1, R2 - Res.-0.25-10k (Brown, black, orange, golden) - 2 pcs.,
R3, R4 - Res. -0.25-4.7 Ohm (Yellow, purple, golden, golden) - 2 pcs.,
C1, C2 - Cond. 100/16V 0611 +105°C - 2 pcs.,
C3 - Cond. 10/16V 0511 +105°C (Capacitance can be increased to 470 µF) - 1 pc.,
C4, C5 - Cond. 470/16V 1013+105°C - 2 pcs.,
C6 – C8 - Cond. 0.1/63V K73-17 - 3 pcs.

Rice. 10. Schematic diagram of an experimental bridge amplifier

Unlike the stereo amplifier circuit (Fig. 3), which assumes that coupling capacitors are present at the output of the previous device, a coupling capacitor is included at the input of the bridge amplifier, which determines the lower frequency reproduced by the amplifier.

Depending on the specific application, the capacitance of capacitor C1 can be from 0.1 μF (fn = 180 Hz) to 0.68 μF (fn = 25 Hz) or more. With capacitance C1 indicated on the circuit diagram, the lower frequency of the reproduced frequencies is 80 Hz.

Internal resistors connected to the inverting inputs of the amplifier through an isolation capacitor C2 are connected to each other, which provides output signals of equal magnitude but opposite in phase.

Capacitor C3 performs correction frequency response amplifier at high frequencies.

Since the potentials of the amplifier outputs are DC equal, it became possible direct connection load, without isolating capacitors.

The purpose of the remaining elements was described earlier.

For the stereo version, you will need two bridge amplifiers on the TDA2822M chip. The connection diagram is easy to obtain using Fig. 4.

Reliable operation of the amplifier in bridge mode is ensured by selecting the appropriate supply voltage depending on the load resistance (see table).

All parts of the bridge amplifier are placed on a printed circuit board measuring 32 x 38 mm made of one-sided foil fiberglass 2 mm thick. Drawing possible option The board is shown in Fig. eleven.

Rice. 11. Placement of elements on the bridge amplifier board

DA1 - TDA2822M ST Housing: DIP8-300 - 1 pc.,
SCS-8 Narrow dip socket - 1 pc.,
R1 - Res.-0.25-10k (Brown, black, orange, gold) - 1 pc.,
R2, R3 - Res. -0.25-4.7 Ohm (Yellow, purple, golden, golden) - 2 pcs.,
C1 - Cond. 0.22/63V K73-17 - 1 pc.,
C2 - Cond. 10/16V 0511 +105°C - 1 pc.,
C3 - Cond.0.01/630V K73-17 - 1 pc.,
C4 – C6 - Cond.0.1/63V K73-17 - 3 pcs.,
C7 - Cond. 1000/16V 1021+105°C - 1 pc.

The schematic diagram of a typical bridge UMZCH and the placement of elements on the printed circuit board are shown respectively in Fig. 12 and 13.

Not long ago I had the idea to practice making miniature devices. Without thinking twice, I went to the website of a regional seller of radio components and during the search process I came across a wonderful solution in the form of the TDA2822L microcircuit. Now about our sheep.

TDA2822L is a low-power, low-voltage integrated UMZCH, which has already been mentioned on this site (it seems like more than once). Its features are two channels, the ability to be powered from a voltage in the range of 1.8 - 12 V (unipolar), low losses, the ability to be switched on via a bridge circuit, and the presence of a solution in an SOP-8 package (not the smallest in nature, but still quite compact). And, by the way, “stupid” it has 1 W per channel (at a 4-ohm load). That is, even with large, powerful headphones, it’s enough for the eyes (more on that later). And it costs $0.37. A fairy tale, and nothing more!

The wiring for it is minimal, and the UMZCH circuit, according to the datasheet, looks like this:

There is nothing fundamentally incomprehensible in this diagram, the details are typical, so let’s move straight to the interesting part, namely, the choice of parts.

Since we are assembling a miniature amplifier, it is clear that the maximum number of parts should be in SMD design, in particular, I managed to make everything in SMD except C4 and C5 (well, our store does not carry electrolytes for SMD installation). As for the power supply, it’s even more interesting - immediately from the moment the idea arose, I decided that I would power the circuit from a tablet like CR2032, fortunately there is a wonderful small holder for them, and since almost all the elements are SMD, the space saving is good. But then, just in case, I decided to add two spots for the wires on the crown, just as a reserve.

Our total list of components:

Chip TDA2822L in SOP-8 package x1.

Resistor 10 kOhm 0805 x2

Resistor 4.7 kOhm 0805 x2

Capacitor 0.1 uF x2

Electrolytic capacitor 470 uF >10 V (I have 16 V) x2

The result is this cute “bobblehead”:

Disclaimer: I noticed that you can get rid of the R0 jumper, inherited from the previous revision of the board, after I soldered the board, so it’s too late to fix it and I’m too lazy

As you can see, the dimensions are, ahem, small. To tell the truth, I didn’t even expect this, although the first version of the board was a little smaller and without a mask, but after making the signet it turned out that the electrolytes would have to be left hanging in the air. Combined with the poor quality of the board of the first version, I enlarged it a little and redesigned it, and everything went like clockwork (to be honest, almost like clockwork, one capacitor still “hangs”).

Note: on the board the chip itself is actually the opposite way around compared to the deeptrace design.

So, having a project in hand, we make a printed circuit board (if you like, I use FR + ammonium persulfate). A few photos of how this is done at home:

I assembled a simple amplifier using a TDA2822M, and it worked right away

But due to an unsuccessful experiment, the micra burned out. Recently I came across a board with such a micro, and I decided to build such an amplifier again. So catch it

The chip, of course, does not provide much, only 1W per channel, but for small speakers this is normal

Here is the circuit of a 2X1W amplifier on TDA2822M taken from the datasheet

Nothing complicated, minimal parts, I assembled the boards with grass in 20 minutes

Set of parts as usual

C1 = 1000mF (16V)
C2,4,6 = 100nF (104)
C3.7 = 470mF (16V)
C5.8 = 100mF (16V)

R1.3 = 10kOhm (brown - black - orange)
R2.4 = 4.7 Ohm (yellow - purple - gold)

Power supply 6-14V, 15V limit. Consumption 200mA

Assembled amplifier on a printed circuit board

Signet drawing from the track side

Signet for 2X1W amplifier on TDA2822M. Just like at home. This article has all the technology

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