Disclaimer: If following this guide anything damages i shall not be held responsible.Do it at your own risk.
Step 1: Components
1- LM 386 semiconductor (IC)
2- 100 micro Farad capacitor
3- 220 micro Farad capacitor
4- 10 ohm resistor
5- 5 kilo ohm variable resistor
6- 100 ohm variable resistor
7- 0.01 capacitor
8- 0.047 capacitor
10- 9V Battery clip
11- 9V Battery
12- 3.5mm stereo jack male
13- 3.5mm stereo jack female
14- Project board (or you can use dotted board and solder)
You can find these electrical components from your nearest electronics store.These all components are easy to find and are common so you won`t have a hard time to find it.
Step 2: Circuit Diagram
Thanks to cld000 for schematic drawing.
Step 3: Placing the IC
2-If you pick the IC in front of you (so you can read what is written on it) then the lower left pin is 1 and the pin number increase anticlockwise.Take a wire and join the 3rd pin to 4th pin(GND pin).
Step 4: 0.0.1 Capacitor
Step 5: GAIN Controller
Join th A pin of this variable resistor with the C pin.Lastly join the 8th pin of IC with the B of this variable resistor.This becomes the GAIN.
Step 6: 100 Micro Farad Capacitor
Step 7: 10 Ohm Resistor & 0.047 Capacitor
Step 8: Volume Controller
Step 9: Input and Output
9-Join the +ve of the 3.5 mm stereo jack male with the other side of the 0.01 capacitor and join the GND of the male jack with the GND of the IC.
Step 10: Testing
Congratulation !!! you have made your own simple audio amplifier.
Now the time to check it out.Join the male jack with your mp3 player or musical instrument and female with the speakers.Now adjust the Volume and Gain to get the best and loudest possible sound.I should notify you that with this amplifier only one speaker will work.And do the adjustment from low to high.Do the adjustment carefully or it can damage your speakers.
You can change the input jacks as your requirement.You can add a 220 micro farad variable capacitor instead of simple 220 micro farad capacitor to change the bass.