Transistors: Explained.

 

Transistors: 

       

While watering the garden you have noticed that the water pressure is low and so you turn the faucet valve to its maximum water gushes out in full strength and you marvel at the power you hold literally at the tip of your fingers, you wonder if only everything else in life is that easy that's probably what the electronics engineers hoped for when they set out to design a device that would allow them to control the flow of current in circuits what they came up with is a semiconductor device called a bipolar Junction transistor transistors are special because they allow you to control how much current goes through all of it some of it or none at all you can do this by controlling the voltage across two of the transistor leads each transistor has three leads emitter-base and collector the collector collects the current and the emitter amidst the current while the base is the region between them depending upon where the three terminals of the transistor are located on the semiconductor we can have either an NPN transistor or a PNP transistor in the transistor symbol an arrow between the emitter and base indicates the direction of current flow, the sequence of doped regions in a PNP transistor is the P region collector n region base P region emitter the sequence of doped regions in an NPN transistor is n region collector P region base in region emitter we can think of a transistor as made of two diodes pointing either towards or away from each other, before we dive into their significance let's take a moment to familiarize ourselves with terminology that is used to describe diodes electrons negatively charged carriers of current holes positively charged carriers of the current result of the flow of changing carriers both holes and electrons doping addition of impurities into a semiconductor to form regions rich and electrons or holes either electron donors like phosphorus or electron acceptors like boron are added into the semiconductor in the region negatively charged area of the semiconductor into which electron donor atoms are added so that there is an extra electron that is free to float away per donor atom P region positively charged area of the semiconductor into which electronic acceptor atoms are added so that there is an extra space or hole created per acceptor atom PN Junction region where the P and n regions meet allowing electrons and holes diffuse across biasing process of adding an outside voltage source to make the diode behave a certain way forward-biased connecting a voltage source such that its positive terminal connects to the P region and negative terminal to the in the region of the diode voltage is greater at the tail-end compared to the pointed end of the diode symbol reverse biased connecting a voltage source such that its positive terminal connects to the in region and negative terminal to the P region of the diode.

 

 

 

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