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To understand how a PNP transistor works, simply flip the polarity or and transistor. A transistor in saturation mode acts like a short circuit between collector and emitter.

Related to transistor: diode, transistor characteristics

transistor,

three-terminal, solid-state electronic device used for amplification and switching. It is the solid-state analog to the triode electron tube

In 1947, Shockley was director of transistor research at Bell Telephone Labs. Brattain was an authority on solid-state physics as well as expert on nature of atomic structure of solids and Bardeen was an electrical engineer and physicist. Within a year, Bardeen and Brittain used the element germanium to create an amplifying circuit, also called.
A Buying Guide for Transistors. Whether youre building, repairing, or maintaining electronics, youll end up needing transistors. Universally useful and adaptable, the transistor is an essential component of electronic circuitry.
Transistor is a science fiction action role-playing video game by Supergiant Games, and the studio's first title since the release of their critically-acclaimed Bastion.The game was released on May 20, 2014 for Windows and PlayStation 4. Later it was also released for Mac & Linux platforms on October 30, 2014, for iOS on June 11, 2015 and Nintendo Switch on November 1, 2018.

electron tube,
device consisting of a sealed enclosure in which electrons flow between electrodes separated either by a vacuum (in a vacuum tube) or by an ionized gas at low pressure (in a gas tube).
...Click the link for more information.; the transistor has replaced the electron tube for virtually all common applications.

Types of Transistors

The transistor is an arrangement of semiconductorsemiconductor,
solid material whose electrical conductivity at room temperature is between that of a conductor and that of an insulator (see conduction; insulation). At high temperatures its conductivity approaches that of a metal, and at low temperatures it acts as an insulator.
...Click the link for more information. materials that share common physical boundaries. Materials most commonly used are silicon, gallium-arsenide, and germanium, into which impurities have been introduced by a process called 'doping.' In n-type semiconductors the impurities or dopants result in an excess of electrons, or negative charges; in p-type semiconductors the dopants lead to a deficiency of electrons and therefore an excess of positive charge carriers or 'holes.'

The Junction Transistor

The n-p-n junction transistor consists of two n-type semiconductors (called the emitter and collector) separated by a thin layer of p-type semiconductor (called the base). The transistor action is such that if the electric potentials on the segments are properly determined, a small current between the base and emitter connections results in a large current between the emitter and collector connections, thus producing current amplification. Some circuits are designed to use the transistor as a switching device; current in the base-emitter junction creates a low-resistance path between the collector and emitter. The p-n-p junction transistor, consisting of a thin layer of n-type semiconductor lying between two p-type semiconductors, works in the same manner, except that all polarities are reversed.

The Field-Effect Transistor

A very important type of transistor developed after the junction transistor is the field-effect transistor (FET). It draws virtually no power from an input signal, overcoming a major disadvantage of the junction transistor. An n-channel FET consists of a bar (channel) of n-type semiconductor material that passes between and makes contact with two small regions of p-type material near its center. The terminals attached to the ends of the channel are called the source and the drain; those attached to the two p-type regions are called gates. A voltage applied to the gates is directed so that no current exists across the junctions between the p- and n-type materials; for this reason it is called a reverse voltage. Variations of the magnitude of the reverse voltage cause variations in the resistance of the channel, enabling the reverse voltage to control the current in the channel. A p-channel device works the same way but with all polarities reversed.

The metal-oxide semiconductor field-effect transistor (MOSFET) is a variant in which a single gate is separated from the channel by a layer of metal oxide, which acts as an insulator, or dielectric. The electric field of the gate extends through the dielectric and controls the resistance of the channel. In this device the input signal, which is applied to the gate, can increase the current through the channel as well as decrease it.

Invention and Uses of the Transistor

The invention of the transistor by American physicists John Bardeen, Walter H. Brattain, and William Shockley, later jointly awarded a Nobel Prize, was announced by the Bell Telephone Laboratories in 1948; it was also independently developed nearly simultaneously by Herbert Mataré and Heinrich Welker, German physicists working at Westinghouse Laboratory in Paris. Since then many types have been designed. Transistors are very durable, are very small, have a high resistance to physical shock, and are very inexpensive. At one time, only discrete devices existed; they were usually sealed in ceramic, with a wire extending from each segment to the outside, where it could be connected to an electric circuit. The vast majority of transistors now are built as parts of integrated circuitsintegrated circuit
(IC), electronic circuit built on a semiconductor substrate, usually one of single-crystal silicon. The circuit, often called a chip, is packaged in a hermetically sealed case or a nonhermetic plastic capsule, with leads extending from it for input, output,
...Click the link for more information.. Transistors are used in virtually all electronic devices, including radio and television receivers, computers, and space vehicles and guided missiles.

See microelectronicsmicroelectronics,
branch of electronic technology devoted to the design and development of extremely small electronic devices that consume very little electric power. Although the term is sometimes used to describe discrete electronic components assembled in an extremely small
...Click the link for more information..

Transistor

A solid-state device involved in amplifying small electrical signals and in processing of digital information. Transistors act as the key element in amplification, detection, and switching of electrical voltages and currents. They are the active electronic component in all electronic systems which convert battery power to signal power. Almost every type of transistor is produced in some form of semiconductor, often single-crystal materials, with silicon being the most prevalent. There are several different types of transistors, classified by how the internal mobile charges (electrons and holes) function. The main categories are bipolar junction transistors (BJTs) and field-effect transistors (FETs).

Single-crystal semiconductors, such as silicon from column 14 of the periodic table of chemical elements, can be produced with two different conduction species, majority and minority carriers. When made with, for example, 1 part per million of phosphorus (from column 15), the silicon is called n-type because it adds conduction electrons (negative charge) to form the majority carrier. When doped with boron (from column 13), it is called p-type because it has added positive mobile carriers called holes. For n-type doping, electrons are the majority carrier while holes become the minority carrier. For p-type doping holes are in larger numbers, hence they are the majority carriers, while electrons are the minority carriers. All transistors are made up of regions of n-type and p-type semiconducting material. SeeSemiconductor, Single crystal

Transistor As A Switch

The bipolar transistor has two conducting species, electrons and holes. Field-effect transistors can be called unipolar because their main conduction is by one carrier type, the majority carrier. Therefore, field-effect transistors are either n-channel (majority electrons) or p-channel (majority holes). For