Technical articles on Electronics and Electrical Engineering topics focused on Basics of EE, Electronic components, power systems and equipment used for generation, transmission, operation, and controls of electricity.
The bipolar junction transistor (BJT) was named because its operation involves conduction by two carriers: electrons and holes in the same crystal. The first bipolar transistor was invented at Bell Labs by William Shockley, Walter Brattain, and John Bardeen so late in 1947 that it was not published until 1948. Thus, many texts differ as to the … Read more
There were some historic crude, but usable semiconductor rectifiers before high purity materials were available. Ferdinand Braun invented a lead sulfide, PbS, based point contact rectifier in 1874. Cuprous oxide rectifiers were used as power rectifiers in 1924. The forward voltage drop is 0.2 V. The linear characteristic curve perhaps is why Cu2O was used … Read more
If a block of P-type semiconductor is placed in contact with a block of N-type semiconductor in Figure below(a), the result is of no value. We have two conductive blocks in contact with each other, showing no unique properties. The problem is two separate and distinct crystal bodies. The number of electrons is balanced by the … Read more
Pure semiconductors are relatively good insulators as compared with metals, though not nearly as good as a true insulator like glass. To be useful in semiconductor applications, the intrinsic semiconductor (pure undoped semiconductor) must have no more than one impurity atom in 10 billion semiconductor atoms. This is analogous to a grain of salt impurity in a … Read more
Quantum physics describes the states of electrons in an atom according to the four-fold scheme of quantum numbers. The quantum numbers describe the allowable states electrons may assume in an atom. To use the analogy of an amphitheater, quantum numbers describe how many rows and seats are available. Individual electrons may be described by the combination of quantum … Read more
Valence: The electrons in the outer most shell, or valence shell, are known as valence electrons. These valence electrons are responsible for the chemical properties of the chemical elements. It is these electrons which participate in chemical reactions with other elements. An over simplified chemistry rule applicable to simple reactions is that atoms try to form a complete … Read more
“I think it is safe to say that no one understands quantum mechanics.” Physicist Richard P. Feynman To say that the invention of semiconductor devices was a revolution would not be an exaggeration. Not only was this an impressive technological accomplishment, but it paved the way for developments that would indelibly alter modern society. Semiconductor … Read more
Energy is defined as the capacity of a body to do work. The energy around us exists in many different forms, however, the most important forms of energy are mechanical energy, electrical energy, and thermal energy. Mechanical energy is expressed as newton meters or joules, while electrical energy can be expressed as watt-sec or kilowatt-hour. … Read more
Brown Black Red Silver Resistor Value is 1k Ohms 10% (1000 ohms or 1 kilo-ohms with a tolerance of plus-minus 5 percent) 10 * 100Ω ± 5% = 1000 Ω ± 5% = 1000 Ω ± 5% OR 1 kilo-ohms ± 5% Also see color coding for 4 Band – 1 ohm resistor And: BROWN … Read more
The internal resistance of a voltmeter connects in parallel to the resistor and impacts overall resistance, which in turn impacts the voltage. Technically this impact is referred to as the loading effect (which we have studied earlier). In this post, you’ll learn a brief explanation of the impact of a voltmeter connected to the circuit … Read more