Valve amplifier thermionic valves. The simplest valve was invented by John Ambrose Fleming while working for the Marconi Company in London in 1904 and named the diode, as it had two electrodes. The diode conducted electricity in one direction only and was used as a radio detector and a rectifier. In 1906 Lee De Forest added a third electrode and invented the first electronic amplifying device, the triode, which he named the "Audion". This additional "control grid" modulates the current that flows between cathode and anode. The relationship between current flow and plate and grid voltage is often represented as a series
Owen Williams (engineer) excelled in mathematics. He was apprenticed to the Electrical Tramways Co. in London in 1907 and at the same time did an engineering degree at the University of London. In 1912 Williams assumed a position as engineer and designer with the Trussed Concrete Company. Seven years later, he started his own consulting firm, Williams Concrete Structures. He was then appointed chief consulting civil engineer to the British Empire Exhibition which included the old Wembley Stadium. The commission also included the Palace of Industry building in Brent, the first building in the United Kingdom to use concrete as the exterior. The