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Transistors: Definition, types, composition


The work to be performed aims to make a summary about some of the types of transistors, in terms of its characteristics, its operating principle (basic principles), its most common modes of connection and applications such as the case of bipolar transistors and Transistor field effect (FET) .9


The transistor is an electronic device semiconductor acts as amplifier, oscillator, switch or rectifier. The term “transistor” ( “transfer resistance”). They are now found in virtually all the household goods of daily use: radios, televisions, tape recorders, audio and video players, microwave ovens, washing machines, MP3 players, cell phones, etc.
The transistor comprises a substrate (usually silicon) and three parts artificially doped (contaminated with specific materials in specific amounts) forming two bipolar junctions, the emitter emitting carriers, the collector which receives or collects and third, which is interposed between the first two, modulates the passage of said carrier (base). The transistor is a current controlled and that amplified current device is obtained.

Transister image

Transistor types

Point-contact transistor:
First transistor, comprises a base germanium semiconductor on which they rest, close together, two metallic points constituting the emitter and collector. The base current is able to modulate the resistance that “ve” in the collector.It is difficult to manufacture (the tips fit by hand), fragile (a blow could move the ends) and noisy, now gone.

transistor image

Bipolar junction transistor:

The junction transistor, is manufactured basically on a single crystal of germanium or silicon, which have qualities of semiconductors, intermediate state between conductors such as metals and insulators as diamond. On the glass substrate, are contaminated in very controlled three zones, two of which are of the same type, NPN or PNP, being formed two unions NP.
The N zone with electron donors (negative charges) and P zone acceptors (positive charges). Elements normally used as acceptors P to indium (In), aluminum (Al) or gallium (Ga) and donors N arsenic (As) or phosphorus (P).Configuration PN junctions, given as transistors result PNP or NPN, wherein the intermediate point always corresponds to the characteristic of the base, and two emitter and collector, although they are the same type and of opposite sign to the base, have different contamination (intentionally spiked impurities) between them (usually the emitter is much more polluted than the collector)


Field effect transistor:
The field effect transistor is a family of transistors based on the electric field to control the conductivity of a “channel” in a semiconductor material. The FET may arise as controlled resistors potential difference.Most FET are made using techniques standard semiconductor processing using the monocrystalline semiconductor wafer as the active region or channel.
The effect transistors are best known field JFET, MOSFET and MISFET.
Sensitive to light, usually infrared. Light is incident on the base region, carriers generated in it. This base carries load transistor into conduction. The phototransistor is more sensitive than the photodiode itself by the effect of transistor gain.
A phototransistor is equal to a common transistor, with the difference that the former can work in 2 ways:
1. As a normal transistor with the base current Ib (common mode).
2. As a phototransistor, when the light incident on this element serves as the base current. IP (lighting mode).
They have been used in tape drives and punch cards, styli, etc. Fiber optic communications is preferred to use photodiode detectors with p-i-n. They can also be used in the detection of nearby objects when they are part of a proximity sensor.
encapsulated widely they used in conjunction with an LED, forming optical switches (opto-switch), which detect interruption of the light beam by an object. There are two versions: transmission and reflection.

Transistor image

A sink is a metallic aluminum component generally used to prevent bipolar transistors heated and damaged.Therefore a way to increase the power of a transistor is to get rid of internal heat of the package.


Power transistor:
They are similar to common transistors, with the difference that withstand high voltages and currents that support, but because it also has to dissipate high power and overheating is prolonged; to avoid sobrerecalentamiento sinks used.
Types of power transistors:
– Bipolar.
– Unipolar or Field Effect Transistor.
– IGBT (Insulated Gate Bipolar Transistor).


Smd Tranistor

As the above we see that the transistors are in the vast majority of electronic products such as Smartphone, Mobile Phones, Laptops, Tablets, etc.
Therefore its use is essential in all kinds of electronic devices because of its variety in types such as bipolar transistors.For the above, we conclude that the transistors in current use are essential for the development of technology devices that require some type of transfer, which is provided by a transistor.

I give my regards to my colleagues who helped make some of this work was completed and both of us we got to finish this work without complications.

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