Arduino is a wonderful rapid prototyping platform capable of making a variety of electronic tools, gadgets, and instruments. The fascination with Arduino has grown to the point where makers are creating devices to educate, entertain, and provide new creative tools for individuals interested in science or technology. Some of the electronic devices that can be built with Arduino include DC motor controllers, musical instruments, robots, and smart toys.

In addition to the devices listed, Arduino can be used to create unique sounds as well. There are several programming techniques used to create sounds using Arduino. For example, the Arduino tone library can be used to create a variety of unusual sounds by varying the pitch, frequency, and duration of a pulse width modulated signal. Another approach is to use the recorded sound WAV files stored on an SD card. Arduino can select these files using an SD card software library, thereby allowing the recorded sounds to be heard through a small signal transistor amplifier. In this chapter, we will explore how to build a sound effects machine capable of playing a variety of sounds recorded on an SD card. Also, a discussion on small signal transistor amplifiers and Serial Peripheral Interface (SPI) communication will be reviewed with the project. A modification project allowing the sounds to be played randomly will be discussed in this chapter as well.