Simple Audio Amplifier

In most cases first project in electronics for beginners is building simple audio amplifier. That is because it requires small number of elements and not a lot of knowledge to build one.

For low power amplifiers we could use integrated circuits like TDA family. But I will show how to make amplifier using operational amplifier. This amplifier is only to proof the concept. It real use can be as preamp for guitar or something like that.

I am not hold responsible for any damage that occurred during reproduction.

Step 1: Parts and Materials

Parts:
- TL071
- two 47 kΩ resistors, 1 kΩ resistor, 100 kΩ trimmer and 10 kΩ trimmer
- three 10 μF capacitors and 100 μF capacitor
- 9 V battery with wires or PSU with 9V output
- cable with 3,5 mm audio jack
- small speaker

Tools:
- breadboard and wires
- pliers and tweezers

For testing you can use MP3 player, computer, mobile phone or any other device with audio output.

Step 2: Schematics

Picture above shows schematic for this project. Schematic isn’t my work. I just modified values.

Trimmer P1 is for adjusting input power. P1 is not necessary. Capacitor C1 is for filtering DC current out from audio signal. With resistors R1 and R2 we set voltage divider. With voltage divider we set working point of amplifier to half of the supplied voltage (4,5 V in this case). Resistor R3 and trimmer P2 are there to set amplifiers gain. Capacitor C3 is output capacitor and it is for filtering output frequency (low cut).

Step 3: Assembly on Breadboard

We assembled amplifier’s circuit on to breadboard. Here you can find how to work with breadboard.

Step 4: Testing

For testing I used MP3 player. Here is video from testing:

Step 5: Conclusion

As I said before, I made this amplifier only to proof the concept. Concept was, that you can make audio amplifier using op amp and some other elements.

Have fun building and using this amplifier!