TDA2822 is an integrated sound amplifier that can be used in both mono and stereo mode. The amplifier on this chip is intended for use where a small audio gain is needed, with a low current consumption, for example, it can be used as a headphone amplifier. I have such headphones, they play normally from the computer, but when listening to music from the phone there is clearly not enough power, by connecting such an amplifier the volume rises at times and there is still a margin.
Supply voltage: 1.8 - 15 Volts
Maximum power output: 1.4 watt
Current consumption at load: R = 32 Ohm and U = 6 V in rest mode, and during operation it fluctuates within.
A little higher you see the circuit of a small amplifier using the TDA2822. The sound volume can be adjusted using a 10 kΩ variable resistor. A 12 volt power supply will be ideal for powering the circuit (there will be the highest output power, excluding speaker impedance), but it will also work from a lower voltage. The microcircuit does not heat up at all, so you do not need to use a heat sink. On the first board, separate large screw fasteners are displayed for input, output and power.
The circuit board can be downloaded here:
Here is another circuit for turning on this chip, as well as two printed circuit boards that are more convenient for making an amplifier for headphones, on one of them there are lower resistors and capacitors for surface mounting, and on the second DIP. They have drawn tracks for jacks for jacks of 3.5 mm, you can easily edit tracks and spots for your connectors. With such a scarf, you need to connect it to the phone (the source of the audio signal) through a special wire with two jacks, and the headphones, respectively, into the connector on the board.
I decided to make an amplifier according to the second scheme using resistors (10k, 4.7) and 100 nF ceramic capacitors for surface mounting (smd). In the photo, the tracks are drawn with a caponlac and a marker marker and a finished board after etching in ferric chloride.
Adjusting the sound volume from the source of the audio signal will upset you, in my case it is the phone volume rocker, the range is too small. To improve the change in sound power, add a miniature variable resistor with a resistance of about 10-50 kOhm to regulate the strength of the input audio.
The NM5 case with dimensions 57x38x19 and a ridiculous price was ideal for my motherboard. The board fits into it perfectly, for the input and output sockets we drill holes of the desired diameter. There is still room for an energy source in the enclosure. In my opinion, it is best to push a lithium-polymer battery there together with a charging module, for example, from USB. As a result, we get an excellent, convenient, compact amplifier for headphones and small speakers for a meager price.
I used this amplifier for small computer headphones, the sound was pretty good, but at high volume the sound quality drops noticeably. I assembled the circuit, as you see, using the TDA2822 in the DIP-8 package, and soldered the shoe to the board for convenience. The output power will depend on the resistance of the headphones and the supply voltage, we don’t need much, we don’t want to go deaf. It is desirable that the speakers are 2x1W / 4 Ohm.
And finally, I’ll say that I recommend collecting this scheme only for beginners. You can’t get unrealistic high-quality sound from industrial and expensive amplifiers, but this is enough for a simple layman. Here's a video for you to familiarize yourself with the properties of the output sound from such a circuit.
