2011 ~ Basic Electronics

The Hidden Cameras for Security

The CCTV digital camera, hidden cam, spy digital camera, secret digital camera or house movie monitoring digital camera is a digital camera that is hidden as another item. These little digital cameras have remarkable quality, yet are little enough to cover up in a radio, smoke detectors, reflection or many other familiar things that would be in a room. Hidden Cameras can be used not only in the property, but over the counter or industrially as video digital cameras.

Today a hidden cameras can record movie for watching later or connected to the world wide web for watching from anywhere in the world at real-time. To get connected to the world wide web you simply need a little system called a USB DVR - Digital Video Recording unit. This system joins directly to your digital camera and your computer to make your movie available online. An IP Camera does not require a USB DVR, but is hard to cover because of its size.

Frequency Domain Curve-Fitting FDCF

Frequency domain curve-fitting is useful technique to fit a TFM very close into the observed FRF data. FDCF is a two-step procedure, which includes the model structure selection and model parameter optimization.

Direct Current Density

Current is known as the flow of charge. By inheritance, the direction of this flow is with the movement of positive charge. The amount of charge δQ flowing through (that is, perpendicular) to a surface, in time δt is given by the formula

Structure and Working Liquid-Filled Transformers

A liquid-immersed transformer is composed of a magnetic core and coil assembly immersed in a fluid, which is normally a mineral oil. The fluid must have firslty good heat transfer characteristics and secondly electrical insulating characteristics.

Power Systems Steady-State Analysis

In steady-state analysis of power systems, any transients from disturbances are considered to have settled down, and the system state is considered as unchanging. Particularly, system loads including transmission system losses, are closely matched with power generation so that the system frequency is becomes constant.

Description and Use of Transformers

A transformer is a static device and it is commonly used all over the world for transforming electric energy from one circuit to another magnetically (that is, by induction rather than by way of conduction). usually, this transformation is accomplished b/w circuits of different voltages but having same frequency

State-Space System Realization SSSR

System realization is a method to find out an internal state-space description for a system given with an external description, normally its TFM or impulse response.

Objectives of Power System and Operation and Control

The main objective of power system operation is providing power to consumers meeting strict tolerances on voltage magnitude and frequency. consequently,

Equivalent distributed Circuit

We can easily symbolized TEM mode in a transmission line by the equivalent circuit, shown in dia4.7 below, for a length Az. Physically, it is said to be distributed circuit because the circuit parts are not lumped at separate locations as in a conventional low-frequency circuit rather they are distributed uniformly along the length of the line. Thus, we can define the elements on per-unit-length basis.

Metal-Oxide-Silicon Capacitor

The metal-oxide-silicon (MOS) capacitor locates in the center of the complementary metal-oxide-silicon (CMOS) technology. MOSFETs place reliance on the very high quality of the interface between SiO2, the standard gate dielectric, and silicon (Si). This tutorials provides the detailed understanding of the MOS capacitor which is helpful in understanding the MOSFETs

Electronic Filters

In electronics the Electrical filters are circuits that are designed to shape the magnitude as well as the phase spectrum of an input signal in order to generate a desired response at the output.

Electron and Hole Velocities and Mobilities

The Electrons and holes performs a chaotic random thermal motion. The average kinetic energy of thermal motion per one electron is given by

3kBT/2

State Variables for Electrical Circuits

As we know that only capacitors and inductors are capable of storing energy in a circuit, and so only the variables related with them are able to place some influence the future condition of the circuit. The voltages from corner to corner of the capacitors and the currents through the inductors may serve as state variables.

Variable Speed Drives

INTRODUCTION

Variable speed drives are very useful in conjunction with supply &return fans & cooling tower fans, In addition to this these are also very helpful in virtually any type of centrifugal pump. In addition, centrifugal chillers are a leading applications. Engineers consider Speed Control and recognize such systems primarily for its energy savings benefits.

Types of Multivibrators

The Multivibrator circuits are classified in 3 general categories.

1- Astable multivibrators.

Astable multivibrators circuits contain no stable state but still keep changing from one state to the other, and so the named as multivibrator. There useful application is as clocks or oscillators. These are also used as a 555 as an astable multivibrator.

The WRIG Phase Coordinate Model

The WRIG is furnished with laminated stator & rotor cores with uniform slots in which 3-phase windings are placed (Fig 2.1 below). Usually, the rotor winding is connected to copper slip-rings.

Brushes on the stator gather (or transmit) the rotor currents from (to) the rotor-side static power converter. For the time being, the slip-ring–brush system resistances are lumped into rotor phase resistances,

Automotive Claw-Pole- Rotor Generator Systems

Enhancing comfort & safety in cars, trucks, & buses driven by combustion engines require more installed electric power on board. As of now, the claw-pole-rotor generator is the only category of automotive generator used in industry, with whole powers per unit up to 5 kW and speeds up to 18,000 rpm

A solid rotor claw-pole structure possessing ring-shaped single direct current (DC) excitation coil, though supplied via slip-rings & brushes from the battery on board, has proven to be simple & reliable, with low cost, low volume and low excitation power loss. In common, the claw-pole-rotor generator is a 3-phase generator with 3 or 6 slots per pole & with 12, 14, 16, 18 poles, & a diode full power rectifier.

Permanent Magnet Synchronous Generator Systems

By the term permanent magnet (PM) synchronous generators (SGs), we imply here radial or axial air gap PM brushless generators with distributed (q greater than 1) or concentrated (q ≤ 1) windings & rectangular or sinusoidal current control having surface PM or interior PM (IPM) rotors.

A PMSG’s output voltage amplitude & frequency both are proportional to speed. In case of constant speed prime mover applications, PMSGs might carry out voltage self-regulation by appropriate design; i.e., inset or interior PM pole rotors. Small speed variation (from ±10 to 15%) may be suitable for diode rectified loads with series capacitors & voltage self-regulation. However, the majority applications require operation at variable speed, and, in this case, constant output voltage vs. load, be it direct current (DC) or alternating current (AC), requires full static power conversion & close-loop control.

Wound Rotor Induction Generators WRIGS

WRIGs have been constructed for powers per unit up to 4 hundred megawatt (MW) in pump-storage power plants & down to 4.0 MW per unit when used in wind power plants. Diesel engine or gas–turbine-driven WRIGs for stand-by or autonomous operation up to twenty to forty MW may also be useful to reduce fuel consumption & pollution for variable load. Under1.5 to 2 MW/unit, WRIGs are not straightforward to justify in terms of cost per performance and benefits against full the power rating converter synchronous or cage-rotor induction generator systems.

Switched Reluctance Generators

This tutorial is on Switched reluctance generators (SRGs). The SRGs are double-saliency electric generators that have non- over-lapping stator multi-phase windings & containing passive rotors. They could also be assimilated with stepper motors with position-controlled pulsed currents. Multiphase configurations are necessary for smooth power delivery & eventual self-starting & for motoring process, if the application requires it. SRGs were studied mainly for the following:

Static Capacitor Exciter Stand-Alone IG for Pumping Systems

Bearing in mind the energy storage capacity or water pumping in a reservoir for later use appears to be the most appropriate ways to employ wind energy, which has a supply that depends on time, by day & season. As variable speed is useful, to tap most of the wind energy from cut-in to cut-off wind speeds, the frequency of the voltage produced by the IG varies noticeably, however the ratio V/f does not vary as that much. For induction-motor-driven pumps, such a situation is satisfactory.

The Machine-Side PWM Converter Control

To make the control system open for motoring & generating, we shall consider that only torque vs speed is performed. In core, a functional generator produces the desired torque versus speed curve desired from the IG (Fig 5.2-a to Fig 5.2-c). For motor starting, the torque vs. speed may decrease notably with speed (Fig 5.2-a)

Variable Speed Generators

The design specifications are made to tie to the application. For a generator-only application (this includes wind generator, auxiliary power generator on aircraft, etc.), the motoring mode is not included from start, at the same time the DC output voltage power bus may be as follows:

Varactor diodes

when a diode is operated inthe reverse biased condition, the width of the depletion region increases as voltage that is applied increases. Varying the width of the depletion region is equivalent to varying the plate separation of a very small capacitor such that the relationship between junction capacitance & applied reverse voltage will look something like that presented in figure below. The typical variation of capacitance supplied by a varactor is from about 50pF to 10pF as the reverse voltage goes up from 2V to 20V. The symbol used for a varactor diode has been shown above.

Transistor operating configurations

There are 3 basic circuit configurations that are used for transistor amplifiers. These 3 circuit configurations depend upon which one connection among the 3 transistor connections is made common to both the input and the output. In the case of bipolar junction transistors, the configurations are referred to as common emitter, common collector or emitter follower, & common base, as shown in diagram below.

Analogue instruments

All analogue electrical indicating instruments need 3 essential devices these devices are briefly discussed below:

1- A deflecting or operating device.

A mechanical force is generated by the current or voltage which causes the pointer to have some deflecition from its 0 position.

2- A controlling device.

The controlling force works in opposition to the deflecting force & ensures that the deflection being shown on the meter is always the same for a given measured quantity. It also pr events the pointer always going to maximum level of deflection. There are 2 main types of controlling devices, which includes spring control & gravity control.

The superposition theorem

This tutorial is superposition theorem. The superposition theorem states:

‘In any network which is made up of linear resistances & containing more than 1 source of e.m.f., the resultantcurrent flowing in any branch is the algebraic sum of the currents that would flow in that branch if eachsource was considered separately, all other sourcesbeing replaced at that time by their respective internal resistances.’

Delta and star connections

The network presented below in Figure 34.1-a) containing 3 impedances Z A, ZB and ZC is said to be π-connected.such network can be redrawn as drawn in Figure 34.1(b),where the arrangement is said to be as delta-connectedor mesh-connected.

The network drawn in Fig 34.2-a, containing of 3 impedances, Z1, Z2 and Z3, is referred to beT-connected. This network can be redrawn as drawn in Figure 34.2(b), where the arrangement is referred to as star-connected.

Current and voltage relationships

Figure 44.3 below presents us a voltage source VS supplied to the input terminals of an infinite line, or a line terminated in its characteristic impedance, so that a current IS flows into the line.At a point, say, one km down the line let the current be I1. The current I1 will not have the same magnitude as IS because of line attenuation; also I1 willlag IS by some angle β. The ratio IS/I1 is therefore aphasor quantity. Let the current a further onekm down theline be I2, & so on, as demonstrated in Figure 44.3 below. Each unit-length of line can be considered as a section of a repetitive network. The attenuationis in the form of a logarithmic decay &

Advanced Electronics formulas

Below is the List of Advanced Electronics formulas:

Comlex numbers formulas
LR-C network formula
LR-CR formulas
Advanced Electronics Determinants
Delta star formula
Star delta formula
Impedance matching formula
Formulas for R-L-C series circuits
Fourier series formulas
Field theory Formulas
Harmonic Analysis Formulas
Formulas for Hysteresis and Eddy current

Shunts and multipliers

An ammeter, which is used for measuring current, offers a low level resistance (ideally 0) & must be connected in series with the circuit.

A voltmeter, which is used for measuring p.d., offers a high level of resistance (ideally I has infinite) & must be connected in parallel with the part of the circuit whose p.d. is required. There is no difference between the basic instrument used to measure current and voltage because both make of use a milliamp meter as their basic part. This is a sensitive instrument which gives f.s.d. for currents of just a few milli amperes. When an ammeter is needed to measure currents of having large magnitudes, a proportion of the current is diverted through a low-value resistance connected in parallel with the meter. Such a diverting type of resistor is referred to as shunt.

Moving-iron instrument

There are two types of moving iron instrument which are discussed below briefly

Attraction type

Figure (a) below demonstrates an attraction type of moving-iron instrument is When current flows in the solenoid, a pivoted soft-iron disc is attracted towards the solenoid & themovement causes a pointer to have some movement across a scale.

Electrical Engineering Formulas (principles and technology)

A.C Theory: all Formulas for a.c circuits

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