How transistor works?

A transistor can act as a switch or an amplifier thanks to its unique architecture. This is done by twisting a valve to control a supply of water, or a little amount of electricity to control a gate on a much bigger supply of electricity. The base, collector, and emitter are the three components that make up a transistor. The base serves as the bigger electrical supply's gate controller. The emitter serves as the outlet for the greater electrical supply, which is located in the collector.

The amount of current flowing through the gate from the collector can be controlled by sending different amounts of current from the base.  This allows for the regulation of enormous currents, such as those in amplifiers, with extremely small currents. The identical procedure is used to generate the binary code for digital processors; however, in this instance, a voltage threshold of five volts is required to open the collector gate.

The transistor is being utilized in this fashion as a binary switch with the following states: five volts "ON," less than five volts "OFF." The transistor is made possible thanks to semi-conductive materials. Both electrically conductive and non-conductive materials are known to the majority of people. Typically, metals are considered to be conductive materials. Materials that are non-conductive or insulators include wood, plastics, glass, and ceramics.

A group of researchers at Bell Labs in New Jersey in the late 1940s found how to employ specific crystal kinds as electronic control devices by taking use of their semiconductive qualities. Typically, the majority of non-metallic crystalline formations would be regarded as insulators. But when impurities like boron or phosphorus are forced into the growth of germanium or silicon crystals, the crystals acquire completely different electrical conductivity characteristics.

A transistor is built by sandwiching this substance between two conducting plates (the emitter and the collector). Electrons collect when current is applied to the semi-conductive material (base), creating a strong conduit that allows electricity to pass through. John Bardeen, Walter Brattain, and William Shockley were the researchers who came up with the transistor. Field effect transistors and junction transistors are the two primary types of transistors. Each operates differently. However, a transistor's capacity to manage a powerful current with a low voltage is what makes it useful. Transistors in a public address system, for instance, amplify (increase) the weak voltage generated when someone speaks into a microphone. The transistors' electrical output is potent enough to power a loudspeaker, which generates noises that are significantly louder than the speaker's voice.


A thin portion of one type of semiconductor material sandwiched between two thicker layers of the opposite type makes up a junction transistor. For instance, the outer layers must be n-type if the center layer is p-type. An NPN transistor is one such device. The emitter layer is one of the outer layers, and the collecting layer is the other. The base is the layer in the middle. Junctions are the points at which the emitter links the base and the base joins the collector.

An NPN transistor needs the correct voltage applied across its layers. It is necessary for the base's voltage to be higher than the emitter's. In turn, the voltage at the collector must be higher than at the base. A battery or another direct current source provides the voltages. Electrons are supplied by the emitter. Because the base has a higher positive voltage than the emitter does, it attracts these electrons from the emitter.  Through the transistor, the flow of electricity is caused by the movement of electrons. Through the base, the current travels from the emitter to the collector. By altering the quantity of electrons in the base, variations in the voltage applied to it change how the current flows. In this manner, slight variations in the base voltage can result in significant variations in the current leaving the collector.

PNP junction transistors are also produced by manufacturers. These devices have an n-type base and a p-type emitter and collector made of semiconductors. The operation of an NPN transistor and a PNP junction transistor is identical. However, it is different in one way. Instead of changing the amount of electrons in the base, a PNP transistor's main current flow is regulated by changing the number of holes. Additionally, this sort of transistor can only function properly if the positive and negative connections are the opposite of those of an NPN transistor.


Only two layers of semiconductor material, stacked one on top of the other, make up a field effect transistor. Through the channel, a layer that is one of the layers, electricity flows. Current passing through the channel is hampered by a voltage attached to the gate on the other layer. As a result, the voltage applied to the gate regulates how much current flows through the channel. The junction field effect transistor (JFET) and the metal oxide semiconductor field effect transistor are the two fundamental types of field effect transistors (MOSFET). MOSFETS make up the majority of the transistors found in modern integrated circuits.

Prasun Barua

Prasun Barua is an Engineer (Electrical & Electronic) and Member of the European Energy Centre (EEC). His first published book Green Planet is all about green technologies and science. His other published books are Solar PV System Design and Technology, Electricity from Renewable Energy, Tech Know Solar PV System, C Coding Practice, AI and Robotics Overview, Robotics and Artificial Intelligence, Know How Solar PV System, Know The Product, Solar PV Technology Overview, Home Appliances Overview, Tech Know Solar PV System, C Programming Practice, etc. These books are available at Google Books, Google Play, Amazon and other platforms.


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