Radio receiver crude triode, was invented in 1906 by Lee De Forest as a more sensitive detector for radio receivers, by adding a third electrode to the thermionic diode detector, the Fleming valve. It was not widely used until its amplifying ability was recognized around 1912. The first tube receivers, invented by De Forest and built by hobbyists until the mid 1920s, used a single Audion which functioned as a grid-leak detector which both rectified and amplified the radio signal. There was uncertainty about the operating principle of the Audion until Edwin Armstrong explained both its amplifying and demodulating functions in a
Electrohydraulic servo valve Electrohydraulic servo valve An electrohydraulic servo valve (EHSV) is an electrically operated valve that controls how hydraulic fluid is sent to an actuator. Servo valves are often used to control powerful hydraulic cylinders with a very small electrical signal. Servo valves can provide precise control of position, velocity, pressure, and force with good post movement damping characteristics. A servo valve receives pressurized hydraulic fluid from a source, typically a hydraulic pump. It then transfers the fluid to a hydraulic cylinder at a pressure that is proportional to an electrical signal that it receives. Most hydraulic control valves are binary, they