Transistor Working

Transistor Basics

A human brain contains 100 billion cells that let us think and remember things. Likewise, a computer contains billions of miniature cells known as transistors. It is a semiconductor device made of silicon, a chemical compound commonly found in sand. Transistors have revolutionised the electronic industries since they were first invented. It was invented by William Shockley in 1947.


A transistor is a semiconductor device that is used to switch or amplify electronic signals and electric power. It consists of semiconductor material mostly with at least three terminals for connection to an external circuit.

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Transistor Working Principle

Transistors are made up of three parts namely:

  • Base
  • Collector
  • Emitter

The base serves as a gate controller device for larger electric supply. The collector is a larger electrical supply and outlet of that supply is the emitter. The current flowing through the gate from the collector can be regulated by sending varying levels of current from the base. In this manner, a very small amount of current can be used to control a large amount of current like in amplifiers. Transistor works as a switch or as an amplifier.

Transistor as an Amplifier

Transistor as an amplifier serves as an energy booster. It comes in useful things like hearing aids, which is one of the prior gadgets people use for a transistor. Hearing aids consist of a tiny microphone that picks up sounds for your world and converts them into varying electric currents. Microphones are also fed into a transistor that boosts a tiny loudspeaker, and you hear a much louder version of sound around you.

Transistor as a Switch

Transistors also work as switches. A small electric current flowing through one part of a transistor can make much larger current flow through the other part. This is how all computer chips work. For instance, a memory chip includes hundreds of transistors, each of which can be switched on or off individually. Since every transistor can be in two separate states, it can store two numbers zero and one separately. A chip can store billions of zeros and ones with billions of transistors and as many letters and numbers.

Learn more about this concept by visiting the link: Transistor as a device – Switch and Amplifier

Applications of Transistor

Semi-conducting materials make the working of transistor possible. Most of you must be familiar with electrically conductive and nonconductive materials. Metals are typically considered to be conductive. Things like plastics, wood, ceramics and glass are insulators, or non-conductive. A team of scientists discovered how to test certain types of crystals and utilize them as electronic control devices by exploiting their semi-conductive properties.

Heat-operated switch

  • A thermistor is one of the most important components in the circuit of a heat-operated switch. It is a kind of resistor that responds to the surrounding temperature. Its resistance decreases when the temperature is high and vice versa.
  • The thermistor resistance drops and a higher share of the supply voltage are dropped across R when the heat is applied to the thermistor. The base current rises followed by an increase in collector current. As a result, the bulb glows and siren sounds.
  • These particular circuits are mainly used in the fire alarm system.

Integrated Circuits

  • Integrated circuits consist of resistors, transistors, diodes and capacitors combined with a silicon wafer-thin chip, known as the microchip.
  • Integrated circuits consume less electrical energy, occupies a small space that reduces the circuit’s size and can be built at low cost.

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