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# Electronics

## NPN Transistor Working Principle

The scientists John Bardeen and Walter Brattain invented the point-contact transistor. It had two wires carefully fused on a crystal of germanium. William Shockley followed these inventions by creating the bipolar, or junction, transistor. These inventions were the beginning of microelectronics. The transistor provided instant circuit operation and eliminated the …

## Half-Wave & Full-Wave Voltage Doubler: Working & Circuit Diagram

It assumed that the source of power is 117-volt ac found in homes and schools. The transformer is used to step up or step down the voltages required for the electronic circuits. Because transformers are heavy and costly, voltage multiplying circuits (voltage doublers) have been devised to raise voltages without …

## Power Supply: Definition, Functions & Components

Definition: A power supply is an electronic circuit designed to provide various ac and dc voltages for equipment operation. Proper operation of electronic equipment requires a number of source voltages. Low dc voltages are needed to operate ICs and transistors. High voltages are needed to operate CRTs and other devices. …

## PN Junction: Formation & Structure

In this section, the PN junction, which forms the basis of photovoltaic devices, is introduced. Silicon (Si) is the most common element used in the construction of photovoltaic solar cells. Recall that the addition of impurities to pure silicon (or other semiconductors) can change the conduction properties and form p …

## PN Junction Diodes and BJT Transistors: an Introduction

This article provides a brief introduction to PN junction diodes and BJT transistors. Doping Silicon: N-Type and P-Type Semiconductors PN junctions play an important role in semiconductor fabrication for integrated circuits. An undoped silicon with a valence of four has an intrinsic concentration of ${{n}_{i}}=1.1\times {{10}^{16}}\text{ }carriers/{{m}^{3}}$ at room temperature. …