Fun project; the sound comes from WAV files stored in EEPROM

PICTURE a pumpkin head, eyes lighting up red and emitting an eerie howl when someone walks past it! Although intended to help generate a bit of fun over Halloween, this project also serves to demonstrate just how easy (and cheap) it can be to output audio in an electronics project. The sound comes from a pre-recorded computer “WAV” file stored in a small non-volatile memory. WAV files can be downloaded from the internet, extracted from music CDs and even recorded by yourself on a PC using software supplied with most operating systems.

The circuit can be configured into one of two modes of operation: Halloween Howler, which includes a light sensor to detect moving objects, and a generic three-input design that allows one of three stored sound samples to be played when an input is asserted. This second setup provides a more general purpose sound generator that can have a number of uses. Only minor component changes are required for the different setups, which are described later.