History[edit]
Main article: History of electrical engineering
Electricity has been a subject of scientific interest since at least the early 17th century. The first electrical engineer was probably William Gilbert who designed the versorium: a device that detected the presence of statically charged objects. He was also the first to draw a clear distinction between magnetism and static electricity and is credited with establishing the term electricity.[1] Then in 1762 Swedish professor Johan Carl Wilcke invented, and in 1775 Alessandro Volta improved, a device (for which Volta coined the name electrophorus) that produced a static electric charge, and by 1800 Volta had developed the voltaic pile, a forerunner of the electric battery.
19th century[edit]
In 19th century, research into the subject started to intensify. Notable developments in this century include the work of Georg Ohm, who in 1827 quantified the relationship between theelectric current and potential difference in a conductor, of Michael Faraday, the discoverer of electromagnetic induction in 1831, and of James Clerk Maxwell, who in 1873 published a unified theory of electricity and magnetism in his treatise Electricity and Magnetism.[2]
Beginning in the 1830s, efforts were made to apply electricity to practical use in thetelegraph. By the end of the 19th century, the world had been forever changed by the rapid communication made possible by the engineering development of land-lines, submarine cables, and, from about 1890, wireless telegraphy.
Practical applications and advances in such fields created an increasing need for standardized units of measure. They led to the international standardization of the units volt,ampere, coulomb, ohm, farad, and henry. This was achieved at an international conference in Chicago in 1893.[3] The publication of these standards formed the basis of future advances in standardisation in various industries, and in many countries the definitions were immediately recognised in relevant legislation.[4]
During these years, the study of electricity was largely considered to be a subfield of physics. That's because early electrical technology was electromechanical in nature. The Technische Universität Darmstadt founded the world's first department of electrical engineering in 1882. The first electrical engineering degree program was started at Massachusetts Institute of Technology (MIT) in the physics department under Professor Charles Cross, [5] though it was Cornell University to produce the world's first electrical engineering graduates in 1885.[6] The first course in electrical engineering was taught in 1883 in Cornell’s Sibley College of Mechanical Engineering and Mechanic Arts.[7] It was not until about 1885 that Cornell PresidentAndrew Dickson White established the first Department of Electrical Engineering in the United States.[8] In the same year,University College London founded the first chair of electrical engineering in Great Britain.[9] Professor Mendell P. Weinbach at University of Missouri soon followed suit by establishing the electrical engineering department in 1886.[10] Afterwards,universities and institutes of technology gradually started to offer electrical engineering programs to their students all over the world.
DEFINITION
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics, and electromagnetism.
This field first became an identifiable occupation in the latter half of the 19th century after commercialization of the electric telegraph, the telephone, and electric power distribution and use. Subsequently, broadcasting and recording media made electronics part of daily life. The invention of the transistor, and later the integrated circuit, brought down the cost of electronics to the point they can be used in almost any household object.
Electrical engineering has now subdivided into a wide range of subfields includingelectronics, digital computers, power engineering, telecommunications, control systems, radio-frequency engineering, signal processing, instrumentation, andmicroelectronics. The subject of electronic engineering is often treated as its own subfield but it intersects with all the other subfields, including the power electronicsof power engineering.
Electrical engineers typically hold a degree in electrical engineering or electronic engineering. Practicing engineers may have professional certification and be members of a professional body. Such bodies include the Institute of Electrical and Electronics Engineers (IEEE) and the Institution of Engineering and Technology (professional society) (IET).
Electrical engineers work in a very wide range of industries and the skills required are likewise variable. These range from basic circuit theory to the management skills required of a project manager. The tools and equipment that an individual engineer may need are similarly variable, ranging from a simple voltmeter to a top end analyzer to sophisticated design and manufacturing software.
PRACTICAL WORK BOOK FOR ELECTRICAL ENGINEERING
http://www.neduet.edu.pk/electronics/Telecommunication/Telecom%20Data/Lab%20Mannuals/FE/BEE.
Synthetic Inductor Based High Pass
Audio Filter
The inductor coil is one of the fundamental electronic components however it is very less used in theelectronic circuits as compared to the other components. The reasons are mainly due to its physical size, sensitivity to the presence of electromagnetic field, unavailability of wide range of inductance values etc. The inductors cannot be included in the Integrated Circuit Chips due to its three dimensional geometry and size. Hence most of the circuit designers try to avoid inductor coils from their circuits and prefer ‘Synthetic Inductor Circuits’ which simulates an inductor using other electronic components.
This article discusses on the design of a Synthetic Inductor circuit and demonstrates its working on a sample application circuit. The Synthetic Inductor can be easily made using a capacitor, Op-amp, a resistor and a variable resistor using which the inductance value can be varied by a large range. When using SMD components the entire circuit will take less space than the actual inductor.
Here the Synthetic Inductor is used to realize a simple high pass filter which can remove the low frequency sounds from a normal audio input. The high frequencies are separated from the low frequency bass-treble before it is fed to normal loudspeakers since they cannot effectively reproduce bass-treble like the woofers does.
Synthetic Inductor Based High Pass Audio Filter
Circuit Design: MFB Bandpass Filter Audio Sub-Woofer
The loudspeakers are devices which are designed to reproduce the actual voice according to the voice frequency signals fed into it. The audible voice spectrum stretches from around 20Hz to 20 KHz and the interesting thing is that there is not loudspeaker design which can reproduce all these frequencies with the same effect. Hence there are different kinds of loudspeakers like Tweeters, Mid-range Speakers, Sub-Woofers and Woofers which can reproduce the voice in their own particular frequency bands only.
In an audio play back device, the entire audio signals are separated into different bands and applied to the corresponding type of loudspeaker. The Tweeters are normally fed with frequencies above 5 kHz, Mid-range speakers are fed with frequencies in the range of 300 Hz to 5 kHz, and Sub-Woofers with 300 Hz to 40 Hz and Woofers are fed with frequencies below 40 Hz.
Since the musical sound normally falls around the maximum frequency of 5 to 8 KHz, Tweeters are not so common in audio devices. For driving the Mid-range Speakers a high pass filter of cut-in frequency around 300 Hz is enough and for Woofers a Low pass filter with cut-off frequency around 40 Hz will suffice. Bass-beats of the songs appear in the Sub-Woofer range and a Band-pass filter can be used to separate out these frequencies from the entire audio signals. This project discusses the design and implementation of a Multiple Feed Back (MFB) Band pass filter for Sub-Woofer frequencies.
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