Another option is a simple, low-power, but very useful amplifier, which is based on the LM386 chip. Its maximum output power is 0.5 watts, which is enough to sound a small room. The pluses of the amplifier on this chip can also include low power consumption, because in standby mode it consumes only 4 mA.
However, you can’t expect high sound quality from such an amplifier, because it is designed, first of all, for minimal cost and profitability. Thus, this amplifier is ideal for voicing, for example, a doorbell signal. If desired, it can also be used in computer speakers or portable audio systems where low power consumption is important.
Amplifier circuit on the LM386
In addition to the chip itself, the circuit contains several resistors and capacitors. Connector CN1 in the diagram is used to connect power, CN2 for the signal source, and a speaker is connected through CN3. PR1 - a variable resistor with which to adjust the volume. The supply voltage of the circuit lies within 4-12 volts, the higher the voltage, the higher the output power. Strongly increase the supply voltage is not worth it, because the chip does not provide for mounting to a radiator and may overheat. The optimum voltage is 9 volts. LED D1 lights up when power is supplied to the amplifier.
As always, start with the circuit board. It has dimensions 65x25 and is performed by the LUT method, the file for printing is attached to the article.
A few photos of the process:
After all the copper is etched, the holes are drilled and the tracks are tinned, you can solder the parts. First, small parts are installed - resistors, after them everything else. Lastly, a variable resistor is soldered. The board provides a seat for jack 3.5, it is very convenient to connect a player or phone to the board using an AUX cable. To connect the power and speaker, there are also places for screw terminal blocks on the board. It should be noted that this amplifier is monophonic, i.e. provides for the connection of only one speaker. To play a stereo signal you need to collect the second one.
pechatnaya-plata.zip [10.1 Kb] (downloads: 178)
Have a nice build!