Signedon sticker: AUDION AMPLIFIER / 3 1/2 Volts / TANTALUM FILAMENT / For FIRST Step Only / Pat Feb 18, 1908
FunctionThis is a modification one of the earliest amplifier vacuum tubes or triodes by Lee De Forest where the anode and grid have been doubled.
It consists of a cathode of whisker-like wires, two plates that acts as an anode, and curved wires between the anodes and the cathode, which were called grids. For some time it remained unclear how exactly the device worked, but the fact was that it enhanced the detection of radio signals. It was shown later that it worked by amplifying the radio signal detected by the circuit: If one connects the cathode and anodes to a voltage source, a current is established, maintained by the electrons produced at the cathode that fly towards the anodes. When one connects the grids to a negative voltage, it will prevent some of the electrons from reaching the anodes, thereby reducing the current. That way one can modify the current by small changes in the grid voltage. If the grids are attached to an antenna, the effect is to amplify the small signal it receives.