what is a transistor?

Answer 1

A transistor is a semiconductor device that uses a small amount of voltage or electrical current to control a larger change in voltage or current. Because of its fast response and accuracy, it may be used in a wide variety of applications, including amplification, switching, voltage stabilization, signal modulation, and as an oscillator. The transistor is the fundamental building block of both digital and analog circuits — the circuitry that governs the operation of computers, cellular phones, and all other modern electronics. Transistors may be packaged individually or as part of an integrated circuit chip, which may hold thousands of transistors in a very small area.

Answer 2

A transistor is a solid state electronic device that can be used as a switch or an amplifier. Solid state means it is made in a crystalline material, not in a vacuum tube like in the old days, which were also used as switches and amplifiers. Tramnsistors are smaller, lighter, more shock resistant and use less power than tubes do.

Most transistors are made of either silicon or germanium. Those elements are non-conductors of electricity. When tiny amounts of the right kind of impurities are added to the crystals, they become a little bit conductive and they are called semi-conductors. We can use them to control voltages and currents.

In fact, the word 'transistor' stands for "transfer resistor". A resistor controls current, but for a given voltage, it can only limit the current to one value. A transistor is much more flexible and can be used to control the current over a wide range of voltages.

The two basic kinds of transistors, no matter what they are made of, are the Field Effect Transistor (FET) and the Bipolar Junction Transistor (BJT).

To understand the FET, think of a garden hose with a pair of vise grip pliers squeezing it. The pliers control he flow of the water. The 'hose' is a microscopic strip of silicon or germanium with the right kind of impurities added to make it conductive. (We call it the 'chanel'.) The 'pliers' is a band of the same material with other impurities added. (We call that the 'gate'.) Both pieces are conductive, but they behave so that there is no electrical current flowing between them.

A current can flow through the chanel, from one end to the other. But if we put a voltage on the gate, it encircles the channel with an electric field. (That's the 'field' in Field-Effect Transistor.) the two pieces do not move, but the field is inside the channel now, and the cross-section of the channel that can carry electricity is shrinking. The higher the voltage, the smaller the area that current can pass through inside the channel. By varying the voltage, the current is changed.

This is how we can take a very small signal, like a radio wave and use an amplifer to boost it up to the point where it is strong enough to make a sound in our earphone.

The other kind of transistor, the BJT, is like a grilled cheese sandwich. There are three layers to it, the bread on either side and the cheese in the middle. In the transistor, the three layers are all silicon, or all germanium. And whatever kind of impurities have been given to the bread, the cheese has the opposite kind. All of the layers are conductive, but they will not conduct between opposite kinds.

By shooting a little current into the middle layer, a much larger current can be made to flow from one side of the sandwich to the other. So, the BJT is a current controlled device, where the FET is a voltage controlled device. But they can both be used as switches, to turn current on and off, and they can both be used as amplifiers, to make weak signals stronger.

That is basically what transistors are and how they work. To really understand how they are made and how to make things like radios with them, you would need to take special courses, but if you have any interest in these things, I strongly encourage you to try. You will find it fascinating and it is a good career field to get into.

I have answered similar questions about transistors before. If this wasn't clear enough, go back and look at some of my previous Best Answers. Good Luck!

29 NOV 06, 2041 hrs, GMT.

Answer 3

The modern transistor is a device which consists of a sandwich of positive or negative types of silicon. In the case of a PNP type transistor, the collector & emitter terminals are positive, & the base terminal negative. With the NPN type, the polarity is reversed. But, basically, if a current is applied to the base terminal, then a greater current will flow through the collector to emitter terminals. This is known as "Gain", or Hfe. So, if you apply a current of 10 to the base, & the output is 100, then the the current gain would be 10. If you applied a current of 1/1,000of an amp to the base, & the gain (or Hfe) was 1,000, then you would get 1 Amp

Answer 4

A transistor was the immediate ancestor to the silicon chip.
Many years ago I was sent to buy a valve for a radio (my Dads) when I eventually found one I was amazed. This thing was like a light bulb!
Anyway Valves were replaced in due course by transistors and heralded the 'transistor radio' and now of course we're back to silicon chips. What comes next?

Answer 5

A transistor is a semiconductor device with 3 electrodes which perform the same functions as a thermionic valve , but smaller and stronger and consuming less power. A transistor radio is a portable , set with transistors as against valves.

Answer 6

A transistor is a solid state device that modulates current. By contrast, a vacuum tube modulates voltage. Modulated current or voltage is what allows us to convert electrical energy (like radio and TV waves) into sound and pictures.

In the 50's and 60's transistors were all the rage in radios, TVs, and such. But they were quickly replaced by etched integrated circuits (IC's) capable of doing what hundreds of transistors were once used to do. ICs ushered in the age of miniaturization that made things like cell phones possible.

Answer 7

A transistor is made up of two type of electrons Positive (P) and Negative (n). you can get two type of transistor (npn or pnp) the basic theory is the same. you have a large voltage on a pin called the "Colloector" (c) then if you apply a smaller voltage to the base pin (b) it allows some to all the voltage out of the imitter (i)
The other type works in the opposite way, that when a voltage is applied to the base it stops the voltage coming out the imitter.

Answer 8

A transistor is a Transfer Resistor.
In effect it is a valve where you apply a current to the base and this lets the electricity pass from the collector to the emitter.

MOSFETS are a similar thing but it is the voltage applied to the gate which lets the electricity flow.

Answer 9

it is a semi conductor made up of silicon which has been "doped" with a material to make it less conductive. They are used as switches and amplifiers.

Answer 10

It depends