#469 LM386 Audio Amp
A basic LM386 audio amplifier with volume and gain control on a breadboard-compatbile mounting.
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.
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:
