The first transistor is made of semiconductor material, germanium in 1950s. In the fabrication of amplifying crystals semiconductor material plays a major role. This effective rise of transistor technology is mainly due to donation and encouragement of many companies including Bell Labs, Motorola, Philco, Raytheon, RCA, Sylvania and Texas Instruments. In 1953 transistor is used in deaf aid, a medical device. The trading of transistors started from 1950’s and first commercial transistor was used in telephonic equipment and military computers in 1952. Image Resource Link: Later the limitations of point contact device, made Shockley alone, to invent junction transistor which dominated the point contact device and is easy to manufacture. Thus the first transistor technology developed was known as point contact device and this technology was regulated by higher performance types. In December, 1947 their experiment with two gold contacts applied to the germanium crystal produced an output signal power greater than the input signal. This breakthrough leads to the discovery of first transistor. But later John Bardeen, Walter Brattain researched and discovered that electrons form a barrier on the surface which is unknown until then. William Shockley experimented on field – effect amplifier but failed. John Bardeen, Walter Brattain conducted experiments under the guidance of Shockley. A Brief History of Transistorsįed up with the large power consumption and low reliability of vacuum tubes director of research, Kelly, at bell laboratories assigned William Shockley to investigate on semiconductors to replace these tubes. Transistors do not require any filament current. So, these restrictions of vacuum tubes are overcome by the transistors. But later these vacuum tubes are replaced by Transistors and Diodes.īecause the vacuum tubes are large in size, a bit expensive and consumes more power when compared with transistors. Later these are used for military applications and tube based audio amplifiers. In early days these vacuum tubes are used in the manufacture of first generation Computers, Radios and Televisions. This construction makes circuit bulky and increase cost. To direct these electrons flow evenly towards anode external electrodes are used which are commonly called as grids. The filament must be continuously charged with constant power in order to heat the cathode. This creates the potential difference between an anode and the cathode thus develops an electric current in the circuit. The produced electrons will flow towards the anode. Later external filament which heats the cathode indirectly is introduced. In early cases, directly the cathode acts as filament, thus when this cathode is heated then electrons will emit from its surface. The cathode is heated by a filament which helps the cathode to emit the electrons. These anode and cathode are placed in a tightly closed glass tube in which vacuum is filled. Vacuum tube consists of an anode and the cathode. Vacuum tubes are also called as electronic tubes or valves. Before the invention of transistors vacuum tubes played a main role in electronics.
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