Sometimes you want your Arduino-based projects to make a loud noise, much louder than what is possible with a piezo or small speaker. To do this, you need to build a small external circuit based around the popular LM386 speaker amplifier IC. The team at RC Car-Arduino have described a simple circuit to allow you to create loud sounds with your Arduino and said circuit, for example:
Not too bad for a small circuit, that can be easily modified for fun and annoying others. To get started head over to the project page here. And we're on twitter and Google+, so follow us for news and product updates as well.