This chip, TDA2003, has found wide application in literally all types of audio systems - it can be found in portable speakers, car radios, computer speakers, televisions and even small music centers. This popularity is due to a combination of several factors - it is cheap, economical in current consumption, provides acceptable sound reproduction quality, and its power is quite enough to sound an entire room. The disadvantages include the fact that it is monophonic, that is, to reproduce a stereo signal you need to assemble two such amplifiers.
Scheme
The amplifier circuit is simple and does not contain any scarce parts. VR1 is a variable resistor with one group of contacts, used to regulate the sound volume. It is advisable to use a resistor with a logarithmic characteristic for smooth adjustment, but a regular linear one will also work. Light-emitting diode HL1 serves to indicate that the amplifier is turned on and lights up immediately when power is applied to the board.The supply voltage of this circuit lies in the range of 8-18 volts, the best option is 12 volts, so all electrolytic capacitors must be taken at a voltage of at least 16 volts, it is advisable to set it higher - 25 volts. The microcircuit, especially when operating at high volumes, heats up noticeably, so it needs at least a small radiator. Capacitor C5 is connected in series with the speaker and cuts off the DC component in the signal, so DC voltage will not appear on the speaker, even if the microcircuit fails.
Amplifier assembly
The entire circuit is assembled on a small printed circuit board measuring 45 x 55 mm, which can be made using the LUT method. The printed circuit board is completely ready for printing on a laser printer and does not require mirroring. After transferring the board, we put it in the etching solution and after etching we get the same result as in the photo below.
Now all that remains is to erase the toner layer, drill holes and tin the tracks and you can start soldering the parts. First of all, small parts are installed - resistors and small capacitors, then everything else. To connect the power wires, speaker and audio source, it is most convenient to use screw terminal blocks, which is what I did. Last but not least, a radiator is installed on the chip; you can use absolutely any one that fits the size of the board.
First launch and tests
To begin with, it is worth checking the correctness of installation, ringing adjacent tracks for short circuits. If everything is assembled correctly, we supply power to the board by connecting the speaker and leaving the signal input unconnected.In this case, it is advisable to turn the volume control to the minimum position so that the input of the microcircuit is connected to ground. We supply power to the board, it should light up immediately Light-emitting diode. Now we carefully turn the volume control; you should hear a slight crackling sound in the speaker, because the input is now “hanging in the air.” This means that the chip is working - now you can input music, for example, from a player, phone or computer. You can connect such an amplifier to any speakers with a resistance of 4-16 Ohms; the lower the speaker resistance, the greater the output power, and, accordingly, the heating of the microcircuit. Happy building!
