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
Jim McDonald (electrical engineer) Jim McDonald (electrical engineer) Sir James McDonald FREng FRSE FInstP FIET is a British educator, serving as Principal and Vice-Chancellor of the University of Strathclyde since 2009. He is also a visiting professor at NYU Tandon School of Engineering. After seven years of work within the UK Electricity Supply Industry, McDonald joined Strathclyde University in 1984 and became Professor of Electrical Power Systems in 1993. In 2001 he was invited to deliver the MacMillan Memorial Lecture to the Institution of Engineers and Shipbuilders in Scotland. He chose the subject "Electric Propulsion in Marine Applications: An Electrical Engineer's Viewpoint". In 2006