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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!
<p>Made it, works great (except at loud volumes). I used a TL072 instead of a TL071, and hooked its 2 amps in parallel, which helped to prevent distortion, and I added a 47uf capacitor to the output, in parallel with the 10uf, which gave it a nice boost in bass</p>
Very nice Instructable, thanks! <br><br>If I don't have trimmer pots, can I use regular pot? How would it change the wiring? <br>Thanks :)
Is the op amp TL071 or TL0711?
Since in the the fig given in step2 ,it is shown as TL0711 and in the components requirement it is given TL071.
<p>most of the time the opamps have the same pinout so zou can use both</p>
<p>most of the time the opamps have the same pinout so zou can use both</p>
<p>most of the time the opamps have the same pinout so zou can use both</p>
<p>It is TL071. Thanks for notification!</p>
<p>can i use op amp 741 instead of TL071?</p>
<p>I used an MCP6002 but it works perfectly. Been struggling to get my own circuit working for ages, and now finally I have a working opamp amplifier! Thank you!</p>
<p>Ive made it with a few modifications, didnt have any potentiometers at hand so i used fixed values and three TL072 instead for increased current handeling (sorry about the wire mess :P)</p>
Little gem MUCH SIMPLER
Very nice instrcuctable. You kept it simple, but thought out. Only thing I would do different is talking about how different components (opamps, caps, etc) can change the sound quality and range; maybe throw in some links to amp kits (CMoy, PIMETA, etc).
Thank you! That is a good suggestion. I will look into it. ;)

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Bio: I am an engineer and a maker who loves technology challenges.
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