Let's start with quick definitions. Electronics involves the design and analysis of electronic circuits. Originally, this subject was referred to as radio engineering. The term "circuit" refers to a collection of components through which electrical current can flow or which use electromagnetic fields in their operation.

Basic circuit design and analysis rests primarily on two Kirchoff's laws, Ohm's law modified for AC circuits, and power relationships (see below). There are also a number of network theorems and methods (such as Thevenin, Norton, Superposition, Y-Delta transform) that are consequences of these three laws.

In order to simplify calculations in AC circuits, sinusoidal voltages and currents are usually represented as complex-valued functions called phasors. With phasors we need to solve algebraic equations instead of differential equations (see below). In general, practical circuit design and analysis requires an understanding of semiconductor devices, integrated circuits, magnetics, DSP, and feedback control.

Here you will find electricity and magnetism reference, basic electrical engineering formulas, calculators, and other related information.

Also see:

Electrical engineering reference: electric network laws and theorems;

Electronic parts datasheet and cross-reference;

Free tech ebooks and white papers;

The guide to accredited online schools, distance learning programs and courses.

**TRANSISTORS AND DIODES: THE BASICS**

** **

The properties of semiconductor devices are studied in college courses. The introduction to the circuits including operation of diodes and transistors and basic formulas can be found in various textbooks or handbooks, such as The Art of Electronics. Below are just some highlights.

The I-V characteristic of a diode is approximated by the Shockley equation:

I=Is×(enVd/Vt-1),

where Is - the reverse bias saturation current (~10−15 to 10−12 A for Silicon); Vd - forward voltage drop in volts; Vt - the thermal voltage (~0.026V at room temperature), n - the "ideality factor" (from 1 to 2). At a fixed current I, voltage drop Vd changes by about -2

mV/oC.

In a bipolar transistor collector current Ic in linear mode is related to the base-emitter voltage by the same Shockley (also called Ebers-Moll) equation, except for n=1. The collector current relates to the base current IB by Ic=IB×h21, where h21 - static current gain (typically 20-1000). However, Ic can't exceed Vin/|Z|, where Vin- the supply voltage, Z- net impedance in the external collector circuit. When Ic reaches the above limit, the transistor is saturated.

Let's start with quick definitions. Electronics involves the design and analysis of electronic circuits. Originally, this subject was referred to as radio engineering. The term "circuit" refers to a collection of components through which electrical current can flow or which use electromagnetic fields in their operation.

Basic circuit design and analysis rests primarily on two Kirchoff's laws, Ohm's law modified for AC circuits, and power relationships (see below). There are also a number of network theorems and methods (such as Thevenin, Norton, Superposition, Y-Delta transform) that are consequences of these three laws.

In order to simplify calculations in AC circuits, sinusoidal voltages and currents are usually represented as complex-valued functions called phasors. With phasors we need to solve algebraic equations instead of differential equations (see below). In general, practical circuit design and analysis requires an understanding of semiconductor devices, integrated circuits, magnetics, DSP, and feedback control.

Here you will find electricity and magnetism reference, basic electrical engineering formulas, calculators, and other related information.

Also see:

Electrical engineering reference: electric network laws and theorems;

Electronic parts datasheet and cross-reference;

Free tech ebooks and white papers;

The guide to accredited online schools, distance learning programs and courses.

**TRANSISTORS AND DIODES: THE BASICS**

** **

The properties of semiconductor devices are studied in college courses. The introduction to the circuits including operation of diodes and transistors and basic formulas can be found in various textbooks or handbooks, such as The Art of Electronics. Below are just some highlights.

The I-V characteristic of a diode is approximated by the Shockley equation:

I=Is×(enVd/Vt-1),

where Is - the reverse bias saturation current (~10−15 to 10−12 A for Silicon); Vd - forward voltage drop in volts; Vt - the thermal voltage (~0.026V at room temperature), n - the "ideality factor" (from 1 to 2). At a fixed current I, voltage drop Vd changes by about -2

mV/oC.

In a bipolar transistor collector current Ic in linear mode is related to the base-emitter voltage by the same Shockley (also called Ebers-Moll) equation, except for n=1. The collector current relates to the base current IB by Ic=IB×h21, where h21 - static current gain (typically 20-1000). However, Ic can't exceed Vin/|Z|, where Vin- the supply voltage, Z- net impedance in the external collector circuit. When Ic reaches the above limit, the transistor is saturated.

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