Control grid Control grid The control grid is an electrode used in amplifying thermionic valves (vacuum tubes) such as the triode, tetrode and pentode, used to control the flow of electrons from the cathode to the anode (plate) electrode. The control grid usually consists of a cylindrical screen or helix of fine wire surrounding the cathode, and is surrounded in turn by the anode. The control grid was invented by Lee De Forest, who in 1906 added a grid to the Fleming valve (thermionic diode) to create the first amplifying vacuum tube, the Audion (triode). In a valve, the hot cathode emits
Charles Brown (engineer) Charles Brown (engineer) Charles Brown (1827–1905) was a British engineer. He was born at Uxbridge on 30 June 1827 and was apprenticed to Maudslay, Sons and Field. In 1851 he moved to Switzerland to join the Sulzer company. In 1871 he left Sulzer to set up Swiss Locomotive and Machine Works (SLM). While at SLM he invented the Brown valve gear, a radial valve gear for steam engines. He became involved in the development of electric locomotives in the 1880s. In 1885 he became manager of Maschinenfabrik Oerlikon and in 1890 he set up Charles Brown and Company at 91