The reason is during practical working of transistor, heat (wasted power) is generated at collector. You might be wondering about largest size of collector region. The collector region has largest area and base has smallest area. The doping level of emitter is highest and base is lowest. In figure above, you may find outer layers similar, but their operations are much different in terms of electrical and physical properties. In construction of BJT, middle region is named as base and outer 2 regions are emitter and collector. You may visit here to learn more about semiconductor, its types, comparison of silicon and germanium etc. Different electronics devices are made by combination of these impure semiconductors. Depending upon impurities added, we get n-type or p-type semiconductors. Adding an impurity (a chemical substance) to pure silicon improves its properties, this process is known as doping. A pure silicon isn’t very useful for electronics. The conductivity of semiconductor materials lies in between conductor (like copper) and insulator (like plastic). There are two semiconductors Silicon (Si) and germanium (Ge) used to make transistors, out of which silicon is mostly preferred. The layer combination can be either npn or pnp. A transistor has a 3 sandwich layers of doped semiconductors. These 3 terminals are named as collector (C), base (B) and emitter (E). Transistors are conceptually 3 terminal active devices. Now, from here we will learn about BJTs, its types, construction, working etc.’ Transistor Symbols You might be thinking about the name bi-polar, why so called? We will see the reason behind this in transistor working. Hence most of people working with electronics use the word transistor for referring BJT. The most common transistor we use is junction transistor (BJT). In transistor tutorials we will learn each and every variation of both types in detail. The transistors are divided into two main types: bi-polar junction transistors (BJT) and field effect transistors (FET). The prefix trans tells about signal transfer from low resistance to high resistance part and istor means solid physical structure having property of resistance. Why transistor is called transistor?Transistor name meaning lies in its own working. By definition, a transistor is a two pn junction semiconductor device used as a switch or to amplify electronic signals. A transistor is simple active electronic device by its physical structure and little bit complex by its working. Later on William Shockley invented bipolar transistors in 1948. This transistor was named as point-contact transistor. The first transistor is practically implemented in 1947 by physicists John Bardeen, Walter Brattain, and William Shockley. Transistor controls electricity with electrons. What is Transistor?Įlectronics is about using extremely minute particles called electrons to control electricity. That’s why transistor is vital part of electronics. Like other electronic components we have discussed so far, transistors do have various types for variety of applications. With its switching and signal amplifying ability transistor replaced use of mechanical switch and vacuum tube in electronics. With this combo abilities transistors can do a lot. You might be thinking that what does a transistor actually do? So, besides amplification (turning low power signal to similar high power signal) transistors can also act as switch. They are responsible for shrinking electronic circuits. Transistors have many advantages like small size, easy availability, low cost, easy to use. The input-output configuration of such ICs is based on transistors.

There are millions of transistors hidden in an integrated circuit like Microcontroller.

Today, most of the electronic circuits are consists of integrated circuits (ICs). The job of current in electronic circuit doesn’t change with direction of current flow.

It doesn’t matter which direction of current flow is considered, what matters is using the same direction consistently. These concepts seem confusing, but they are very clear and both are acceptable. Hence electron flow is from Negative to Positive. Electron with its negative charge get easily attracted towards positive source. Yes, that looks conceptually wrong but, you may find its proof in diode symbol. Conventional current flows from Positive to Negative. As the name suggest conventional current is traditional, old fashion way of expressing the concept of current. You will see the concept of conventional current v/s electron flow in this tutorial couple of times. The construction and working of transistor is related to diodes, you are suggested to read tutorials on diodes and basic electronics. Before going on journey of transistors, we recommend you to have a look on some basics linked with transistors.

Signal path of a transistor