Antique Radio Design and the Mac - Similarities in design developments in the appearance of vintage radios and Macintosh computers.
Discover Cicuits - More than 6000 electronic circuit schematics. Each has been carefully categorized and cross-referenced. Included are circuits, with descriptions, designed by David A. Johnson and links to other circuits.
How a Vacuum Tube Works - Construction and operation principles, from Svetlana Electron Devices.
Worldwide Vintage Wireless Database - This section of the Martin Francis web site is dedicated to UK and North American Vintage wireless from 1920's to the 1960's. Picture galleries include 2000+ photographs of radios and valves / tubes.