Revolutionary invention of transistor


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We are living in an incredible time of development, one that has already started to change the way we live our lives. With 40% of our world’s population currently in the age of Internet-connected information, mankind is more intertwined than before. And all this is possible due to the invention of the transistor. Transistor is a basic and very important component in smartphones and computers

Before the invention of the transistor

Before transistors came into existence, vacuum tubes were used in place of transistors. They looked like heavy glass bulbs. The triode vacuum tube consisted of 3 parts, cathode, grid, and anode. When a current was passed through the cathode, it started heating up. Due to heat, the cathode released electrons. Since gases have been removed from the gases, electrons had very little resistance to their movement. And thus they are easily attracted towards positively charged anodes. In this way the circuit is completed and the current flows. But the use of grids can manipulate the flow of electrons in many useful ways. For example, it could be used as a switch if a light bulb was placed here. And if there is any positive voltage in the grid, the bulb will light up. If a negative voltage was applied, the negatively charged electrons would pass through.

And this is the foundation of binary coding i.e. 0s and 1s, on which most modern technology depends. Here 1 is the positive voltage and 0 is the negative voltage. Turns the light on and 0 turns off the light.

Vacuum tube


The ENIAC was the world’s first general-purpose electronic computer. It was designed by John Mauchly and J.Presper Eckert. It consisted of 18000 vacuum tubes. It was built in 1945. It was built during World War I to calculate the trajectory for artillery. It can perform complex calculations in 30 minutes, which takes the average human 24 hours to calculate. But it weighed 30 tons and required a full room. More power is required to operate it as a cathode in vacuum tubes required for heating to work. Thus the vacuum tube burned regularly and needed to be replaced.


Now, this computing power can be contained in a silicon chip. And the size of the transistor used for smartphones or computers is similar to sand grains. A modern phone has about 2 billion transistors, which perform the same exact function as a vacuum tube, but at a nanoscale. The transistors in the CPU are micro and are manufactured with incredible precision with machines on thin wafers of silicon crystal. These are cut from silicon ingots.


N-type and P-type semiconductors are connected together to form different types of transistors. The most common transistor among all transistors is the NPN transistor. The transistor operates at n-type and p-type junctions due to free electrons and holes. Free electrons in the N-type will migrate to fill the p-type pores. This creates a boundary layer called a depletion layer. The layer prevents more electrons from passing through, repeating each other due to negative charges. However, when a positive voltage is applied to the base, it negates that reducing layer and allows current to flow and thus completes the circuit. And for these purposes, various logic gates have been built. The AND, OR, and NOR gates are used to construct transistor circuits. The simplest circuits that can easily perform various calculations are half-additive circuits. But more complex circuits are used to carry out various calculations in one phase. Modern computers can perform millions of calculations in just a few seconds and it is still accelerating.

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