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Project Notes

#469 LM386 Audio Amp

A basic LM386 audio amplifier with volume and gain control on a breadboard-compatbile mounting.



Often I’ll want to monitor an audio signal as part of a breadboard circuit. One could plug into an external amplifier, or build an amplifier circuit on the breadboard.

Since I do this quite often, I decided to put a standard LM386 audio circuit on to some perfboard, with pins arranged so that it can be plugged directly into a breadboard.

Circuit Design

The circuit is based on examples that are documented in the “Typcial Applications” section of the datasheet.

Specifically, I have chosen to include:

  • a volume control pot
  • variable gain (20x to 200x) configuration of capacitor and variable resistor
  • 3.5mm socket for speaker or line out

I decided not include capacitive coupling on the audio input - assuming this and any impedance matching would be taken care of by the audio source.


First tested the circuit directly on a breadboard, with a 1kHz sine wave from a function generator:



Protoboard Layout and Final Build

Some notes on the protoboard layout I used. NB: an important decision to make is which way around you prefer to orient a breadboard and it’s power rails. I prefer as illustrated:



Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.