DIY LM386 Mini Amplifier

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DIY LM386 Mini Amplifier


If you’ve ever wanted a tiny amplifier for your guitar, a retro console, or just to boost the sound from your phone, the LM386 audio amplifier IC is a perfect choice. It’s cheap, easy to wire, and surprisingly powerful for its size.

In this post we’ll build a simple amplifier, then add a few extras to make it more versatile. I've used my guitar pedal prototyping board just for ease of building with a guitar input.

How the LM386 Works

The LM386 is a low-voltage power amplifier IC. At its heart, it takes a small audio signal and boosts it enough to drive a speaker.

  • Runs on 5–12 V DC (a 9 V battery works great).

  • Drives an 8 Ω speaker at a comfortable volume.

  • Default gain is 20×, but you can boost it to 200× with a capacitor between pins 1 and 8.

Parts You’ll Need

  • 1 × LM386 IC

  • 1 × 10 µF capacitor (for optional gain boost, non-polarized if possible)

  • 1 × 220 µF electrolytic capacitor (output coupling)

  • 1 × 100 nF capacitor (power decoupling)

  • 1 × 10 kΩ potentiometer (for volume)

  • 1 × 8 Ω speaker

  • 1 × 9 V battery + clip

  • 1 × input jack (for guitar, console, or phone, or use previously build guitar pedal prototype board)

  • Breadboard or protoboard + wires

Circuit diagram

Wiring It Up (Basic Amp)

Here’s the step-by-step wiring:

Power

  • Pin 6 → +9 V (battery +).

  • Pin 4 → Ground (battery –).

Input Jack and Potentiometer

  • Input jack tip (signal) → Potentiometer side lug A. (Yellow wire in the photo)

  • Input jack sleeve (ground) → Ground.

  • Pot side lug B → Ground.

  • Pot wiper (middle lug) → Pin 3 of LM386.


This way the pot works as a volume control, dividing the input signal before it reaches the amp.

Output

  • Pin 5 → + side of 220 µF electrolytic capacitor.

  • – side of that capacitor → Speaker (+).

  • Speaker (–) → Ground.

Bypass (for stability)

  • Pin 7 → Ground through 100 nF capacitor. (Photo shows it before the speaker is attached)

Optional Gain Boost

Place a 10 µF capacitor between pins 1 and 8.

Unused Pin

  • Pin 2 → Not connected.

Extras to Try

  • Tone Control: Add a simple RC filter before the input.

  • On/Off Switch: Use your 3PDT stomp switch for a pedal version.

  • Enclosure: Mount everything on a bit of acrylic and 3D-print a speaker grille or box.

  • Guitar Pedal Mode: Wire it with your pedal jacks and stomp switch to use as a boost pedal.

What You’ll Hear

This will output a gritty crackly sound. Which does add to the charm, but some is unnecessary and will need cleaning up by adding different components. This is something that you can play around with to get your own amplifier sound.

Why This Project Rocks

  • Quick win: A working circuit in under an hour.

  • Expandable: Add features and turn it into your own custom pedal or mini speaker box.





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