A Brief History Of The Valve or Vacuum Tube. The late 19th and early 20th centuries were a golden age of science and technological research, laying the foundations of the modern world and the electronic age. The list of scientists involved with research into evacuated tubes reads like a whos who of the great innovators of the time - Guthrie, Edison, Tesla, Flemming. Thermionic emission was first reported in 1873 by Thomas Guthrie, but it wasnt until 10 years later in research by Thomas Edison into the Edison Effect that this was really noted - Edison patented the effect, never being backwards in considering the commercial potential of any of his work. Apart from giving us the light bulb these researchers paved the way for John Ambrose Flemming to develop what he called the oscillation valve in 1904 whilst working for the Marconi company. This became known as the Flemming valve or later, the diode. With this seemingly simple innovation, John Ambrose Flemming gave birth to the electronics age and ushered in the modern world. This simple valve was used initially as a rectifier and a radio detector. In 1907, Lee De Forest added a screen to the valve and the triode was born, the first valve signal amplifying device - he named it the Audion. Valve amplification was first used in amplifying telephone signals for long distance use and later in the burgeoning wireless market after the first world war. This triode design was revised subsequently by Eric Tigerstedt in 1914, Irving Langmuir in 1915 (the Pilotron) and closely followed by the French type R valve in 1916 which was extensively used in radio communications during WW1. These last two were probably the first proper valves with hard vacuums and laid the foundations for everything that came after. The inter-war years were the time when electronics first really invaded the home, with the growing popularity of the wireless and in the late 1930s the development of television - the valve being integral to these first mass market electronics. The second world war again drove technological advances, with radar and the first computer - the Colossus code breaking machine at Bletchly Park in England. This machine used hundreds of vacuum tubes and was vital to the war effort in cracking German military codes. The post war consumer boom of the 1950s and 1960s brought further advances in valve design, with the tetrode, pentode, miniature tubes, specialised tubes, rugged tubes and many more being developed - frequently with development being driven by military requirements. The rise of the gramophone and the rapid spread of TV kept the tube manufacturers busy. This period saw the birth of the first real Hi-Fi amplifiers capable of full range reproduction. The 1947 Williamson audio power amplifier typified this new breed with an advanced circuit topology incorporating negative feedback to reduce distortion (Negative feed back having first been proposed by Harold Stephen Black in 1927). Designs continued to evolve, leading to classics like the Quad II series in the UK. By the late 1960s and early 1970s, time was running out for the valve due to the rise of solid state electronics with the transistor and latterly ICs (Integrated Circuits) taking over. Valves became limited to more specialist applications including high power radio transmission and specialised military communications (especially in the Soviet Bloc) due to their inherent resistance to the effects of EMP (electromagnetic pulse) from a nuclear detonation. Tubes were continually popular in guitar amplifiers and began to enjoy a renaissance in the Hi-Fi world in the late 20th century with the development of many new valve amplifiers catering to the high end hi-fi world and appealing to a whole new generation of audiophiles (myself included!). With the advent of the iPod generation, valves have got in on the act again with tube powered amplification in the iTube docking station. Valves have even left the solar system on board the Pioneer series of spacecraft in nuvistor format. Today, this is largely where the vacuum tube is - in a few niche markets, where it does very well. Tubes are still manufactured around the world, especially in China (Shuguang), Russia (Svetlana and others), Slovakia (JJ-Electronic) and even the USA (Westrex Inc.) - they will be around for many years to come. the time when electronics,