71552 VACUUM TUBE ELECTRONICS AT WORK 1940s WESTINGHOUSE PROMOTIONAL FILM
Produced by Westinghouse during WWII, this film explains how electronic vacuum tubes work from the simple diode (single pole switch) to the complex Cathode Ray tube. As the film shows, tubes with grids can be used as electronic amplifiers, rectifiers, electronically controlled switches, oscillators, and for other purposes. Some of the innovations shown in the film include tubes used as rectifiers (for AC/DC conversion and production of metal such as aluminum), an early kind of tube based electrostatic air purifier called a Precipitron, tubes used in radio transmitters and radio telephones (as seen around the 00:08:10:00 mark), for remote control, analysis and testing, for television, X-rays and more. Manufacture of tin plate (00:11:32:00) is also shown, with tubes generating high frequency current to make the process possible. Dialetric heating is shown being used to laminate plywood and test plastic, and increasing the load carrying capacity of transmission lines. <p><p>At 00:10:20:00, a recreation is shown of the first radio broadcast made at the Westinghouse Studios of the election of Warren G. Harding.<p><p>Electronic control of various systems in manufacturing is detailed starting around the 13 minute mark. These systems provided an enormous edge for American manufacturing during the war by increasing efficiency. Photo cells and tubes -- "electronic eyes" -- are shown operating relays, transforming light into current and transforming current into light. (An early TV tube appears at the 16 minute mark). Fluorescent tubes are also shown, and a discussion of sterile lamp rays is shown at about 18 minutes. And one of the great developments of the war -- radar -- is shown at the 18:30 mark.<p><p>In electronics, vacuum tube, electron tube (in North America), tube, or valve (in British English) is a device that controls electric current through a vacuum in a sealed container. Vacuum tubes mostly rely on thermionic emission of electrons from a hot filament or a cathode heated by the filament. This type is called a thermionic tube or thermionic valve. A phototube, however, achieves electron emission through the photoelectric effect. Not all electron tubes contain vacuum: gas-filled tubes are devices that rely on the properties of a discharge through an ionized gas.<p><p>The simplest vacuum tube, the diode, contains only an electron emitting cathode and an electron collecting plate. Current can only flow in one direction through the device between the two electrodes, as electrons emitted by the hot cathode travel through the tube and are collected by the anode. Adding control grids within the tube allows control of the current between the two electrodes. <p><p>Invented in about 1910, vacuum tubes were a basic component for electronics throughout the first half of the twentieth century, which saw the diffusion of radio, television, radar, sound reinforcement, sound recording and reproduction, large telephone networks, analog and digital computers, and industrial process control. Although some applications had counterparts using earlier technologies such as the spark gap transmitter or mechanical computers, it was the invention of the vacuum tubes that made these technologies widespread and practical. In the forties the invention of semiconductor devices made it possible to produce solid-state devices, which are smaller, more efficient, more reliable, more durable, and cheaper than tubes. Hence, in the '50s and '60s, solid-state devices such as transistors gradually replaced tubes. The cathode-ray tube (CRT) remained the basis for televisions and video monitors until superseded in the 21st century. However there are still a few applications for which tubes are preferred to semiconductors; for example, the magnetron used in microwave ovens, and certain high frequency amplifiers.<p><p>“Electronics at Work” is the title of this black-and-white film produced by Westinghouse, and focuses on the role of electronics during World War II. Mark 00:48 introduces the viewer to a diode (a specialized electronic component with two electrodes — the anode and the cathode — separated by a vacuum). At mark 01:35, the film offers further illustration as to the process. When the cathode is heated, negative electrons fly to the positive anode. This “new kind of switch,” the narrator explains at mark 02:15, is explained in great detail via diagrams, as is its use of a rectifier, which converts alternating current (AC), which periodically reverses direction, to direct current (DC) The applications of rectification are plentiful, it is said at mat 03:13, and include electric railways, electro-plating operations, use in steel mills, and in airpower. Diodes can also be used to amplify, it is said at mark 07:08, via a placement of a grid in the center of the diode, which can enhance communication. Further functions of a diode include generation of alternating current (mark 09:13), control the flow of power to a machine (mark 13:07), the ability to transform light into current (mark 14:50), and the ability to transform current into light (mark 16:23). “The cathode ray tube is an example of this application,” the narrator explains. (A CRT uses one or more electron guns and a phosphorescent screen to view images). A CRT was used in early television, it is noted at mark 16:37, and also as an x-ray tube. “Doctors can now study human internal organs … or photograph them,” it is explained. Each way is explained in detail and illustrated by a variety of graphics. Despite the detail devoted to the topic, the narrator notes at mark 18:25 that there are countless other uses. “So many and so varied are the applications of electronics that a single film like this can only mention one in a thousand. We haven’t even mentioned, for instance, radar, the electronic development that helped save Britain during the decisive weeks of the German aerial blitz … Whenever Hitler’s bombers attacked, at whatever altitude, from whatever direction, British Interceptors were waiting for them.” As an array of tubes fill the screen, the narrator concludes at mark 19:41: “Yes the electronic tube, in essence, is only a switch, but what a switch! It rectifies, amplifies, generates, controls, transforms light into electricity and back into light again. These tubes that look so mysterious are essentially simple … in the world of today they’re helping us win a war. In the world of tomorrow, they bring new levels of achievement, comfort, and security.” <p><p>This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD and 2K. For more information visit http://www.PeriscopeFilm.com