## Types of DC Motors

The different types of dc motors share the common names of dc generators such as shunt, series, and com- pound. The construction of the motors is similar to the generator counter parts. Shunt DC Motor In the shunt motor, the field windings shunt across, or in parallel to, the armature, …

## Setting up Your Apple Watch

Why do you need an iPhone? The Apple Watch has many capabilities, but it can’t do everything on its own. It works in tandem with your iPhone to perform many functions. Having an iPhone is not optional; you must have one to use your Apple Watch. You need an iPhone …

## Getting to Know Apple Watch | How to Use the Apple Watch

Anatomy of the Apple Watch The sleek, streamlined design of Apple Watch is designed for easy, intuitive use and has few external parts and pieces. Apple Watch Models Apple Watch comes in three different models, with options that can be mixed and matched to create 38 different variations. When it …

## Ideal Operational Amplifier

Amplifiers are an essential aspect of many electronic applications. Perhaps the most familiar use of an amplifier is to convert the low-voltage, low-power signal from a digital audio player (e.g., iPhone or MP3 player) to a level suitable for driving a pair of earbuds or headphones, as shown in Figure 1. …

## Zener Diode as Voltage Regulator

For many applications, it is desirable that a DC supply be steady and ripple-free. Voltage regulators are used to ensure that the output of a DC supply is steady and relatively independent of load. The most common device employed in voltage regulation schemes is the Zener diode. Zener diodes are …

## PN Junction Theory for Semiconductor Diodes

A simple section of n- or p-type material is not particularly useful for the construction of electronic circuits. However, when sections of n- and p-type material are brought in contact to form a PN junction, a diode is formed. Diodes have a number of interesting and useful properties that are due entirely to the nature of the PN …

## Physical Limitations of Operational Amplifier

Practical op-amps are not ideal but exhibit limitations that should be considered in the design of instrumentation. In particular, in dealing with relatively large voltages and currents, and in the presence of high-frequency signals, it is important to be aware of the non-ideal properties of the op-amp. Figure a: Operational …

## Inverting & Non-Inverting Operational Amplifier Basics

An operational amplifier (op-amp) is an integrated circuit (IC) that contains a large number of microscopic electrical and electronic components integrated on a single silicon wafer. An op-amp can be used in conjunction with other common components to create circuits that perform amplification and filtering, as well as mathematical operations, such as addition, subtraction, …

## Enhancement Mode MOSFET

Figure 1 depicts the circuit symbol and the construction of a typical n-channel enhancement-mode MOSFET. The device has four regions: the gate, the drain, the source, and the bulk. Each of these regions has its own conducting terminal. The bulk and source terminals are often electrically connected, in which case the bulk terminal is not shown in the …

## Bipolar Junction Transistor (BJT) Theory

A Bipolar Junction Transistor (BJT) is formed by joining three sections of alternating p- and n-type material. An NPN transistor is a BJT with a thin, lightly doped p-type base region sandwiched between a heavily doped n-type emitter region and a large, lightly doped n-type collector region. The Bipolar Junction Transistor (BJT) counterpart to the NPN is the PNP transistor, which utilizes the same doping scheme …

## Voltage and Currents in Star (Wye) and Delta Connected Loads

Most of the AC power used today is generated and distributed as three-phase power, which implies three sinusoidal sources, each out of phase with the other. The primary benefit is efficiency: The weight of the conductors and other components in a three-phase system is much lower than that in a single-phase …

## Instantaneous and Average Power Formula

When a linear electric circuit is excited by a sinusoidal source, all voltages and currents in the circuit are also sinusoids of the same frequency as the source. Figure 1 depicts the general form of a linear AC circuit. Figure 1 Time and frequency domain representations of an AC circuit. …

## Low Pass and High Pass Filter Bode Plot

Frequency response plots of linear systems are often displayed in the form of logarithmic plots, called Bode plots after the mathematician Hendrik W. Bode, where the horizontal axis represents frequency on a logarithmic scale (base 10) and the vertical axis represents either the amplitude or phase of the frequency response …

## Band Pass Filter Frequency Response

Using the same principles and procedures in the case of low and high pass filters, it is possible to derive a band pass filter frequency response for particular types of circuits. Such a filter passes the input to the output at frequencies within a certain range. The analysis of a …

## Low Pass and High Pass Filter Frequency Response

There are many practical applications that involve filters of one kind or another. Modern sunglasses filter out eye-damaging ultraviolet radiation and reduce the intensity of sunlight reaching the eyes. The suspension system of an automobile filters out road noise and reduces the impact of potholes on passengers. An analogous concept …

## Fourier Series

The aim of this article is to introduce the concept of frequency domain analysis of signals, and specifically the Fourier series. Later in this article, we explain how it is possible to represent periodic signals by means of the superposition of various sinusoidal signals of different amplitude, phase, and frequency. …

## Second Order System Transient Response

In general, a second-order circuit has two irreducible storage elements: two capacitors, two inductors, or one capacitor and one inductor. The latter case is the most important in terms of new fundamentals; however, the important aspects of all second-order system responses are discussed in this section. Since second-order circuits have …

## First Order System Transient Response

First-order systems are important in all engineering disciplines and occur frequently in nature. Such systems are characterized by a single state variable, where the system energy is proportional to the square of the state variable. That energy is dissipated by the system such that the rate of change of the …

The i -v relationships of resistors, capacitors, and inductors can be expressed in phasor notation. As phasors, each i-v relationship takes the form of a generalized Ohm’s law: $\text{V=IZ}$ where the phasor quantity Z is known as impedance. For a resistor, inductor, and capacitor, the impedances are, respectively: \$\begin{matrix}{{Z}_{R}}=R & …