The circuit aims to imitate a chirping canary made of electronic circuit components such as the Hartley Oscillator. Hartley Oscillator – a variable frequency oscillator circuit where a center tapped ...

For almost a century, between the late 1890s until 1986, coal miners relied on canary birds rather than fellow miners to detect increasing levels of colorless, odorless carbon monoxide and other toxic ...

The miners of yore kept caged canaries to warn of dangerous gas build up as they worked below ground. The birds would chirp away while the air was good, but would fall silent & sicken if conditions ...