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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.

Build

Notes

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.

Schematic

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

Breadboard

LM386AudioAmp_bb_build

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:

LM386AudioAmp_protoboard_layout

LM386AudioAmp_build

Credits and References

About LEAP#469 Breadboard BlingAudioOpAmp
Project Source on GitHub Return to the LEAP Catalog

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

LEAP is my personal collection of electronics projects, 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 (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.