De Forest Files Audion Patent
The Audion was an electronic detecting or amplifying vacuum tube invented in 1906 by Lee de Forest. It was the first widely used electronic device which could amplify current. De Forest was granted a patent for his early two-electrode version in 1906, and the triode (three-electrode) version in 1908. There were patent disputes over the device, partially because de Forest underestimated how wide the use cases would be for his device, such as a telephone receiver amplifier.