Prototypes of all-transistor AM radio receivers were demonstrated, but were really only laboratory curiosities.
Technical feats previously requiring relatively large, mechanically fragile, power-hungry vacuum tubes were suddenly achievable with tiny, mechanically rugged, power-thrifty specks of crystalline silicon.
This revolution made possible the design and manufacture of lightweight, inexpensive electronic devices that we now take for granted. Understanding how transistors function is of paramount importance to anyone interested in understanding modern electronics.
My intent here is to focus as exclusively as possible on the practical function and application of bipolar transistors, rather than to explore the quantum world of semiconductor theory. Discussions of holes and electrons are better left to another chapter in my opinion.
Here I want to explore how to use these components, not analyze their intimate internal details. In taking this approach, however, I assume that the reader possesses a certain minimum knowledge of semiconductors: A bipolar transistor consists of a three-layer "sandwich" of doped extrinsic semiconductor materials, either P-N-P in Figure below b or N-P-N at d.
Each layer forming the transistor has a specific name, and each layer is provided with a wire contact for connection to a circuit. The schematic symbols are shown in Figure below a and d. For any given state of operation, the current directions and voltage polarities for each kind of transistor are exactly opposite each other.
Bipolar transistors work as current-controlled current regulators.
In other words, transistors restrict the amount of current passed according to a smaller, controlling current. The main current that is controlled goes from collector to emitter, or from emitter to collector, depending on the type of transistor it is PNP or NPN, respectively.
The small current that controls the main current goes from base to emitter, or from emitter to base, once again depending on the kind of transistor it is PNP or NPN, respectively.
According to the standards of semiconductor symbology, the arrow always points against the direction of electron flow. P and N, as the main current goes from emitter to collector or vice versa.
In other words, two types of charge carriers -- electrons and holes -- comprise this main current through the transistor. This is the first and foremost rule in the use of transistors: The small, controlling current is usually referred to simply as the base current because it is the only current that goes through the base wire of the transistor.
Conversely, the large, controlled current is referred to as the collector current because it is the only current that goes through the collector wire. No current through the base of the transistor, shuts it off like an open switch and prevents current through the collector.
A base current, turns the transistor on like a closed switch and allows a proportional amount of current through the collector. Collector current is primarily limited by the base current, regardless of the amount of voltage available to push it.
The next section will explore in more detail the use of bipolar transistors as switching elements. Bipolar transistors are so named because the controlled current must go through two types of semiconductor material: The current consists of both electron and hole flow, in different parts of the transistor.
The three leads of a bipolar transistor are called the Emitter, Base, and Collector. Transistors function as current regulators by allowing a small current to control a larger current.
The amount of current allowed between collector and emitter is primarily determined by the amount of current moving between base and emitter.Introduction The bipolar junction transistor consists of three regions.
Germanium transistors will have a forward base/emitter bias voltage of 0. The transistor identified in the above data sheet is a very early device, with the low serial number “43”. S. 3,1,- and I,, represent the dc base currents used to bias the transistors (typically.
This article gives the information about what is a bipolar junction transistor, Types of BJT, advantages, applications and characteristics of the bipolar junction transistors.
I hope the given information in the article is helpful to give some good information and understanding the . Aug 13, · The invention of the bipolar transistor in ushered in a revolution in electronics.
Technical feats previously requiring relatively large, mechanically fragile, power-hungry vacuum tubes were suddenly achievable with tiny, mechanically rugged, power-thrifty specks of crystalline silicon. The Bipolar Junction Transistor (BJT) is a three layer device constructed form two semiconductor diode junctions joined together, one forward biased and one reverse biased.
There are two main types of bipolar junction transistors, (BJT) the NPN and the PNP transistor. Introduction to Bipolar Junction Transistors (BJT) Chapter 4 - Bipolar Junction Transistors The invention of the bipolar transistor in ushered in a revolution in electronics.
Introduction To Bipolar Transistors The Bipolar Junction Transistor 6 of 19 The Designer’s Guide Community mtb15.com 4 The Bipolar Junction Transistor A transistor combines two junctions and has three terminals as shown in Figure 7.