Friday, August 21, 2009

Arduino – Amplified Speaker Project

I have been playing around with the Arduino for a couple of months. The Arduino is an inexpensive open-source electronics prototyping platform ( The compilation below represents a very simple project to connect an amplified speaker to the Arduino.

The amplifier I used for this project is an LM386. The LM386 is a power amplifier designed for use in low voltage applications. It ant the other parts needed for this project , capacitors, resistors and a speaker, can be purchased at Radio Shack.

This example makes use of a Sound Hello World sketch by David Fowler to generate tones.

This also represents my first attempt at a circuit schematic using the freeware version of Eagle from CadSoft at

My hope is that someone will find this useful and will be able to follow what I have done as I have done following the examples posted by others.



//Arduino Sound Hello World
//Created by David Fowler of
//Define the I/O pin we will use for our sound output
#define SOUNDOUT_PIN 9

void setup(void){
  //Set the sound out pin to output mode

void loop(void){
  //Generate sound by toggling the I/O pin High and Low
  //Generate a 1KHz tone. set the pin high for 500uS then
  //low for 500uS to make the period 1ms or 1KHz.

  //Set the pin high and delay for 1/2 a cycle of 1KHz, 500uS.

  //Set the pin low and delay for 1/2 a cycle of 1KHz, 500uS.

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