# Alternating Current (AC)

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## Alternating Current (AC) Tutorials

## What is a radian? – Angular frequency (video)

What is a radian?

The radian is the angle that cover the portion of the circumference which is equal to the length of the radius of the circle

## The Decibel – Voltage Gain & Power Gain

Voltage gain and Power Gain on an Amplifier – Explanation and formulas. The decibel expresses a ratio of quantities, not a quantity itself.

## Power in AC Circuit

Electric power. Electrical power on a circuit with reactive load (reactance). How to obtain the current in a circuit having resistance and reactance.

## Series RC circuit connected to an AC voltage

In a series RC circuit, the current through the resistor and the capacitor is the same. The voltage VS is equal to the phasor addition of the voltage drop across the resistor (Vr) and the voltage drop across the capacitor (Vc).

## Resonance in an RLC Circuit

Resonance in RLC Circuits is a special condition for parallel and series RLC circuits, when capacitive reactance and inductive reactance have the same magnitude and cancel each other. This only happens at frequency fo.

## Impedance (Z) = (Resistance + Reactance)

Impedance (Z) shows the opposition to the flow of direct or alternating current. Impedance is the vector addition of resistance (R) and reactance (X).

## Power Factor Definition (PF) – Power Factor Formulas

Power factor is the ratio between the energy that is converted into work and the electrical energy consumed in a circuit or device

## Properties of the Alternating Current (AC)

What is Alternating Current?

The difference between an alternating current and a continuous current is that the continuous current flows only on one direction. The alternating current circulates first in one direction and then on the opposite one, repeating this process continuously.

## Nonlinear Amplitude Control of a Sinusoidal Oscillator

Nonlinear Amplitude Control of a Sinusoidal Oscillator In any practical oscillator, the loop gain (ßA) must be slightly greater than unity to prevent that the tolerance parameters of components, aging, temperature…

## Half Wave Rectifier – Half-wave Rectifier. Circuit diagram

The half-wave rectifier rectification process.

Polarization of semiconductor diode in the forward and in the reverse direction. Input and output waveforms

## Push – Pull Amplifier – Push – Pull Amplifier Operation

Push – Pull Amplifier

A Push – Pull amplifier is called that way, because it uses 2 groups of transistors and only one works at a time. One group pushes in one direction while the other pulls in another direction. Each group is responsible for amplifying a single phase of the input wave.

## Parallel RC circuit

Parallel RC circuit

Voltage, Currents, Phasor diagram & Impedance. Voltage is the same on the capacitor and resistor. Current is ahead of the voltage in the capacitor

## Sinusoidal oscillator (basic structure)

Basic structure of the sinusoidal oscillator

The sinusoidal oscillator basic structure consists of an amplifier (A) and a selective frequency network (ß) connected in a positive feedback loop

## Crystal Oscillators – Piezoelectric Oscillator. Equivalente circuit

The Crystal Oscillators (Piezoelectric Oscillator) A quartz crystal has a property called: piezoelectric effect. This effect causes, by applying a mechanical pressure on the surface of the crystal, that a voltage is developed…

## Wien-bridge Oscillator with Op Amp

Wien-bridge Oscillator using Op-Amp The Wien-bridge oscillator, as shown on the basic outline of the diagram below, consists of an Operational Amplifier (OA) in a non-inverting configuration with gain 1+R2/R1 and a RC…

## Phase Shift Oscillator

The Phase Shift Oscillator The phase shift oscillator, whose basic structure is described in the picture 1.a has a a negative gain amplifier (-K) and a feedback network consisting of a third order…

## Sinusoidal oscillators – Basic principles

Sinusoidal Oscillators Sinusoidal oscillators play an important role in electronic systems that use harmonic signals. Despite that, in many instances are known as linear oscillators, it is necessary to use some non-linear…

## LC Oscillator – Inductance – Capacitance Oscillator

LC oscillator: Inductance – Capacitance Oscillator A simple oscillator can be built with an amplifier stage and an inductive-capacitive network (LC) to provide an offset of -180° The oscillation frequency can be freely adjusted…