Film: 3486

Media | 1950 | Sound | B/W

Synopsis:

The development of radio and television. Transistors compared to valves.
Crystal set, man uses set with cat's whisker. Thermionic valves. Early radios and televisions. Five valve receiver. Valve in television. The computer of the National Physical Laboratory which uses 5000 valves. Radar dishes. Diagram is used to explain differences between radio waves and radar. Crystal detector used in radar. Early computer. Crystal diode research. Semi-conductor. Principles of the atom in relation to conductivity of metals explained in detail in diagram form. Examples are provided of Antimony and Indium. Germanium diode principles, batteries. The emittor, the base and collector explained. Transistors. Portable value radios compared to transistors radios which are far smaller due to the use of transistors. Ventilation systems required for cooling purposes where large volume of valves are used. Such cooling isn't required when transistors are used as they don't generate heat. A panel with many transistors mounted close to each other. A hair grip hearing aid, one of the first uses of transistors.


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