The second was the all clear - a single, continuous note. After it was confirmed the skies were clear of enemy aircraft the 'all clear' would sound. It brought relief to countless thousands as ...

This clip offers a specially-created montage of air-raid sounds, including an air-raid siren sounding the warning, the sound of aircraft and bombing, and ending with the 'all clear' siren.

which is a unique motor-generator device used during the second world war to generate high plate-voltage from the 28 VDC aircraft bus. These radios make for a great first-WW2 radio restoration ...