This instructable will cover all the basics involved in building an electronic canary. This is a excellent weekend project. This circuit recreates accurately the sound produced by a canary. All components for this project should cost under $10 Basic soldering and electronic skills required For a preview for the sound it makes. The file is below the picture.
Electronic Canary.wma167 KB
http://www.instructables.com/id/Electronic-Canary/