Transistors are semiconductors that generate, control, and amplify electrical signals. It is an essential component of microchips and integrated circuits. Basically, what transistors do is move weak signals from low to high resistance circuits.
Some transistors are equipped with three terminals known as the collector, base, and emitter. The left side of a transistor is the collector diode. The thin layers in the middle part are the base diode. The right side is the emitter. There are also transistors with three terminals classified as drain, gate, and source.
History of Transistors
On December 23, 1947, New Jersey-based Bell Laboratories demonstrated the first transistor, which was an invention of Walter Brattain, John Bardeen, and William Shockley. However, the principles and concept of field-effect transistor was already introduced back in 1925 by Julius Edgar Lilienfeld. The Bell Labs transistor was a bipolar point-contact transistor.
In 1948, Shockley came out with an improved version of the transistor; this time it was called the bipolar junction transistor or BJT.
There are two types of transistors: BJT and the field-effect transistor or FET.
BJT or Bipolar Junction Transistor
Bipolar transistors consist of two back-to-back positioned PN diode junctions. They are current devices, so their main objective is to amplify current. BJTs operate using holes and electrons, which explains their name.
FETs or field-effect transistors, unlike BJTs, are voltage devices. They are also unipolar and can help amplify weak signals of both digital and analog variety. The two types of field-effect transistors are IGFET or Insulated-Gate Field-Effect Transistor and MOSFET or Metal-Oxide Semiconductor Field-Effect Transistor.
Transistors are found in many devices, including watches, cameras, pacemakers, calculators, and hearing aids.