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  1. Transformer - Wikipedia › wiki › Trafo
    • Principles
    • Construction
    • Classification Parameters
    • Applications
    • History
    • Bibliography

    Ideal transformer

    An ideal transformer is a theoretical linear transformer that is lossless and perfectly coupled. Perfect coupling implies infinitely high core magnetic permeability and winding inductances and zero net magnetomotive force (i.e. ipnp - isns = 0).[c] A varying current in the transformer's primary winding attempts to create a varying magnetic flux in the transformer core, which is also encircled by the secondary winding. This varying flux at the secondary winding induces a varying electromotive...

    Transformer EMF equation

    If the flux in the core is purely sinusoidal, the relationship for either winding between its rms voltage Erms of the winding, and the supply frequency f, number of turns N, core cross-sectional area a in m2 and peak magnetic flux density Bpeak in Wb/m2or T (tesla) is given by the universal EMF equation: 1. E rms = 2 π f N a B peak 2 ≈ 4.44 f N a B peak {\\displaystyle E_{\\text{rms}}={\\frac {2\\pi fNaB_{\\text{peak}}}{\\sqrt {2}}}\\approx 4.44fNaB_{\\text{peak}}}


    A dot convention is often used in transformer circuit diagrams, nameplates or terminal markings to define the relative polarity of transformer windings. Positively increasing instantaneous current entering the primary winding's ‘dot’ end induces positive polarity voltage exiting the secondary winding's ‘dot’ end. Three-phase transformers used in electric power systems will have a nameplate that indicate the phase relationships between their terminals. This may be in the form of a phasordiagra...


    Core form = core type; shell form = shell type Closed-core transformers are constructed in 'core form' or 'shell form'. When windings surround the core, the transformer is core form; when windings are surrounded by the core, the transformer is shell form. Shell form design may be more prevalent than core form design for distribution transformer applications due to the relative ease in stacking the core around winding coils. Core form design tends to, as a general rule, be more economical, and...


    The electrical conductor used for the windings depends upon the application, but in all cases the individual turns must be electrically insulated from each other to ensure that the current travels throughout every turn. For small transformers, in which currents are low and the potential difference between adjacent turns is small, the coils are often wound from enamelled magnet wire. Larger power transformers may be wound with copper rectangular strip conductors insulated by oil-impregnated pa...


    It is a rule of thumb that the life expectancy of electrical insulation is halved for about every 7 °C to 10 °C increase in operating temperature (an instance of the application of the Arrhenius equation). Small dry-type and liquid-immersed transformers are often self-cooled by natural convection and radiation heat dissipation. As power ratings increase, transformers are often cooled by forced-air cooling, forced-oil cooling, water-cooling, or combinations of these. Large transformers are fil...

    Transformers can be classified in many ways, such as the following: 1. Power rating: From a fraction of a volt-ampere (VA) to over a thousand MVA. 2. Duty of a transformer: Continuous, short-time, intermittent, periodic, varying. 3. Frequency range: Power-frequency, audio-frequency, or radio-frequency. 4. Voltage class: From a few volts to hundreds of kilovolts. 5. Cooling type: Dry or liquid-immersed; self-cooled, forced air-cooled;forced oil-cooled, water-cooled. 6. Application: power supply, impedance matching, output voltage and current stabilizer, pulse, circuit isolation, power distribution, rectifier, arc furnace, amplifier output, etc.. 7. Basic magnetic form: Core form, shell form, concentric, sandwich. 8. Constant-potential transformer descriptor: Step-up, step-down, isolation. 9. General winding configuration: By IEC vector group, two-winding combinations of the phase designations delta, wye or star, and zigzag; autotransformer, Scott-T 10. Rectifier phase-shift winding c...

    Various specific electrical application designs require a variety of transformer types. Although they all share the basic characteristic transformer principles, they are customized in construction or electrical properties for certain installation requirements or circuit conditions. In electric power transmission, transformers allow transmission of electric power at high voltages, which reduces the loss due to heating of the wires. This allows generating plants to be located economically at a distance from electrical consumers.All but a tiny fraction of the world's electrical power has passed through a series of transformers by the time it reaches the consumer. In many electronic devices, a transformer is used to convert voltage from the distribution wiring to convenient values for the circuit requirements, either directly at the power line frequency or through a switch mode power supply. Signal and audio transformers are used to couple stages of amplifiers and to match devices such...

    Discovery of induction

    Electromagnetic induction, the principle of the operation of the transformer, was discovered independently by Michael Faraday in 1831 and Joseph Henry in 1832. Only Faraday furthered his experiments to the point of working out the equation describing the relationship between EMF and magnetic flux now known as Faraday's law of induction: 1. | E | = | d Φ B d t | , {\\displaystyle |{\\mathcal {E}}|=\\left|{{\\mathrm {d} \\Phi _{\\text{B}}} \\over \\mathrm {d} t}\\right|,} where | E | {\\displaystyle |{\\m...

    Induction coils

    The first type of transformer to see wide use was the induction coil, invented by Rev. Nicholas Callan of Maynooth College, Ireland in 1836. He was one of the first researchers to realize the more turns the secondary winding has in relation to the primary winding, the larger the induced secondary EMF will be. Induction coils evolved from scientists' and inventors' efforts to get higher voltages from batteries. Since batteries produce direct current (DC) rather than AC, induction coils relied...

    First alternating current transformers

    By the 1870s, efficient generators producing alternating current (AC) were available, and it was found AC could power an induction coil directly, without an interrupter. In 1876, Russian engineer Pavel Yablochkov invented a lighting system based on a set of induction coils where the primary windings were connected to a source of AC. The secondary windings could be connected to several 'electric candles'(arc lamps) of his own design. The coils Yablochkov employed functioned essentially as tran...

    Beeman, Donald, ed. (1955). Industrial Power Systems Handbook. McGraw-Hill.CS1 maint: ref=harv (link)
    Calvert, James (2001). "Inside Transformers". University of Denver. Archived from the original on May 9, 2007. Retrieved May 19, 2007.
    Coltman, J. W. (Jan 1988). "The Transformer". Scientific American. 258 (1): 86–95. Bibcode:1988SciAm.258a..86C. doi:10.1038/scientificamerican0188-86. OSTI 6851152.CS1 maint: ref=harv (link)
    Coltman, J.W. (Jan–Feb 2002). "The Transformer [Historical Overview]". IEEE Industry Applications Magazine. 8 (1): 8–15. doi:10.1109/2943.974352.CS1 maint: ref=harv (link)
  2. Nikola Tesla - Wikipedia › wiki › Nikola_Tesla

    4 days ago · Nikola Tesla (/ ˈ t ɛ s l ə / TESS-lə; Serbian Cyrillic: Никола Тесла, pronounced [nǐkola têsla]; 10 July [O.S. 28 June] 1856 – 7 January 1943) was a Serbian-American inventor, electrical engineer, mechanical engineer, and futurist best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

  3. Communication Revolution: A History of Radio – Brewminate › communication-revolution-a
    • Invention and Early Growth
    • 19th Century
    • 20th Century
    • Later 20Th-Century Developments
    • Radio Broadcasting
    • Broadcast and Copyright
    • Radio Station Regulation in The United States
    • Licensed Commercial Public Radio Stations
    • Appendix

    The idea of wireless communication predates the discovery of “radio” with experiments in “wireless telegraphy” via inductive and capacitive induction and transmission through the ground, water, and even train tracks from the 1830s on. James Clerk Maxwell showed in theoretical and mathematical form in 1864 that electromagnetic waves could propagate through free space.It is likely that the first intentional transmission of a signal by means of electromagnetic waves was performed in an experiment by David Edward Hughes around 1880, although this was considered to be induction at the time. In 1888 Heinrich Rudolf Hertz was able to conclusively prove transmitted airborne electromagnetic waves in an experiment confirming Maxwell’s theory of electromagnetism. After the discovery of these “Hertzian waves” (it would take almost 20 years for the term “radio” to be universally adopted for this type of electromagnetic radiation) many scientists and inventors experimented with transmitting and d...

    The meaning and usage of the word “radio” has developed in parallel with developments within the field of communications and can be seen to have three distinct phases: electromagnetic waves and experimentation; wireless communication and technical development; and radio broadcasting and commercialization. In an 1864 presentation, published in 1865, James Clerk Maxwell proposed theories of electromagnetism, with mathematical proofs, that showed that light and predicted that radio and x-rays were all types of electromagnetic waves propagating through free space. In 1886–88 Heinrich Rudolf Hertz conducted a series of experiments that proved the existence of Maxwell’s electromagnetic waves, using a frequency in what would later be called the radiospectrum. Many individuals—inventors, engineers, developers and businessmen—constructed systems based on their own understanding of these and other phenomena, some predating Maxwell and Hertz’s discoveries. Thus “wireless telegraphy” and radio...

    Overview In 1900, Brazilian priest Roberto Landell de Moura transmitted the human voice wirelessly. According to the newspaper Jornal do Comercio(June 10, 1900), he conducted his first public experiment on June 3, 1900, in front of journalists and the General Consul of Great Britain, C.P. Lupton, in São Paulo, Brazil, for a distance of approximately 8 kilometres (5.0 mi). The points of transmission and reception were Alto de Santana and Paulista Avenue. One year after that experiment, de Moura received his first patent from the Brazilian government. It was described as “equipment for the purpose of phonetic transmissions through space, land and water elements at a distance with or without the use of wires.” Four months later, knowing that his invention had real value, he left Brazil for the United States with the intent of patenting the machine at the U.S. Patent Office in Washington, D.C. Having few resources, he had to rely on friends to push his project. Despite great difficulty,...

    Following development of transistor technology, bipolar junction transistors led to the development of the transistor radio. In 1954, Regency introduced a pocket transistor radio, the TR-1, powered by a “standard 22.5V Battery”. In 1955, the newly formed Sony company introduced its first transistorized radio, the TR-55. In 1957, Sony introduced the TR-63, the first mass-produced transistor radio, leading to the mass-market penetration of transistor radios.It was small enough to fit in a vest pocket, and able to be powered by a small battery. It was durable, because there were no tubes to burn out. Over the next twenty years, transistors displaced tubes almost completely except for picture tubes and very high power or very high frequency uses. In the early 1960s, VOR systems finally became widespread for aircraft navigation; before that, aircraft used commercial AM radio stations for navigation. (AM stations are still marked on U.S. aviation charts). By the mid-1960s, the Radio Corpo...

    Overview The beginning of radio broadcasting started with different creations of developing the radio receivers and transmitter including the crystal sets and the first vacuum tubes. These help to transmit the radio waves for long distance broadcasting. Crystal Sets The most common type of receiver before vacuum tubes was the crystal set, although some early radios used some type of amplification through electric current or battery. Inventions of the triode amplifier, motor-generator, and detector enabled audio radio. The use of amplitude modulation (AM), by which soundwaves can be transmitted over a continuous-wave radio signal of narrow bandwidth (as opposed to spark-gap radio, which sent rapid strings of damped-wave pulses that consumed much bandwidth and were only suitable for Morse-code telegraphy) was pioneered by Fessenden and Lee de Forest. The art and science of crystal sets is still pursued as a hobby in the form of simple un-amplified radios that ‘runs on nothing, forever...

    When radio was introduced in the early 1920s, many predicted it would kill the phonograph record industry. Radio was a free medium for the public to hear music for which they would normally pay. While some companies saw radio as a new avenue for promotion, others feared it would cut into profits from record sales and live performances. Many record companies would not license their records to be played over the radio, and had their major stars sign agreements that they would not perform on radio broadcasts. Indeed, the music recording industry had a severe drop in profits after the introduction of the radio. For a while, it appeared as though radio was a definite threat to the record industry. Radio ownership grew from two out of five homes in 1931 to four out of five homes in 1938. Meanwhile, record sales fell from $75 million in 1929 to $26 million in 1938 (with a low point of $5 million in 1933), though the economics of the situation were also affected by the Great Depression. The...

    Wireless Ship Act of 1910 Radio technology was first used for ships to communicate at sea. To ensure safety, the Wireless Ship Act of 1910 marks the first time the U.S. government implies regulations on radio systems on ships.This act requires ships to have a radio system with a professional operator if they want to travel more than 200 miles offshore or have more than 50 people on board. However, this act had many flaws including the competition of radio operators including the two majors company (British and American Marconi). They tended to delay communication for ships that used their competitor’s system. This yields the tragic incident of the sink of the Titanic in 1912. Radio Act of 1912 In 1912, the sinking of the Titanic due to delayed emergency signals. This happened due to many uncontrolled waves from different radio stations that interfered with the emergency signal from the ship. After this tragedy, the government passed on the Radio Act of 1912 to prevent the story to r...

    The question of the ‘first’ publicly targeted licensed radio station in the U.S. has more than one answer and depends on semantics. Settlement of this ‘first’ question may hang largely upon what constitutes ‘regular’ programming 1. It is commonly attributed to KDKA in Pittsburgh, Pennsylvania, which in October 1920 received its license and went on the air as the first US licensed commercial broadcasting station on November 2, 1920 with the presidential election results as its inaugural show, but was not broadcasting daily until 1921. (Their engineer Frank Conrad had been broadcasting from on the two call sign signals of 8XK and 8YK since 1916.) Technically, KDKA was the first of several already-extant stations to receive a ‘limited commercial’ license. 2. On February 17, 1919, station 9XM at the University of Wisconsin in Madison broadcast human speech to the public at large. 9XM was first experimentally licensed in 1914, began regular Morse code transmissions in 1916, and its first...

    Endnotes 1. “James Clerk Maxwell (1831-1879)”. ( 2. Ralph Baierlein (1992). Newton to Einstein: The Trail of Light. Cambridge University Press.Retrieved 3 February2018. 3. “Section 22: Word Origins”. 4. W. Bernard Carlson, Tesla: Inventor of the Electrical Age, 2013, pages 125-126 5. Sungook Hong, Wireless: From Marconi’s Black-box to the Audion, MIT Press, 2001, page 2 6. T. K. Sarkar, Robert Mailloux, Arthur A. Oliner, M. Salazar-Palma, Dipak L. Sengupta, History of Wireless, 2006, page 271 7. Brian Regal (2005). Radio: The Life Story of a Technology. Greenwood Publishing Group. p. 22.Retrieved 3 February 2018. 8. Carlson (2013) page 132 9. Thomas H. White (1 November 2012). “Nikola Tesla: The Guy Who DIDN’T ‘Invent Radio'”. 10. Hong (2001) pages 5-10 11. John W. Klooster (2009). Icons of Invention: the Makers of the Modern World from Gutenberg to Gates. ABC-CLIO. 12. G. R. M. Garratt, The Early History of Radio: From Fa...

  4. downloadyoutubeguitar 🙅That You Can Build Today‎ › downloadyoutubeguitar › acoustic

    Jul 10, 2021 · downloadyoutubeguitar When raised, there is typically a retaining wall holding up the outside edge and ... It can also be surrounded by full plantings to make it a greener and more ...

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  5. centerrebuildsewing 😣Plans and Projects - › centerrebuildsewing › sewing-center

    Jul 03, 2021 · centerrebuildsewing 😣Plans and Projects. The rule of thumb — and it’s a very good rule — is to wait until nighttime temperatures are reliably in the 50s to put tropical p

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  6. Home – › blog

    Jun 28, 2021 · It is animated by six cams (with one of the end cams side-pinned to serve double duty), all driven by a worm gear speed reducer. The motions include left arm, right arm, head tilt, head pan, eyebrows, eyes, and mouth. The manufacturer was the Character Display Co., 3249 Lakewood Avenue, Chicago 13, Illinois.


    Jun 28, 2021 · It is animated by six cams (with one of the end cams side-pinned to serve double duty), all driven by a worm gear speed reducer. The motions include left arm, right arm, head tilt, head pan, eyebrows, eyes, and mouth. The manufacturer was the Character Display Co., 3249 Lakewood Avenue, Chicago 13, Illinois.

  8. Bipolar Transistor Tutorial, The BJT Transistor › transistor › tran_1
    • Bipolar Transistor Configurations
    • The Common Base (CB) Configuration
    • The Common Emitter (CE) Configuration
    • The Common Collector (Cc) Configuration
    • Bipolar Transistor Summary

    As the Bipolar Transistoris a three terminal device, there are basically three possible ways to connect it within an electronic circuit with one terminal being common to both the input and output. Each method of connection responding differently to its input signal within a circuit as the static characteristics of the transistor vary with each circuit arrangement. 1. Common Base Configuration– has Voltage Gain but no Current Gain. 2. Common Emitter Configuration– has both Current and Voltage Gain. 3. Common Collector Configuration– has Current Gain but no Voltage Gain.

    As its name suggests, in the Common Base or grounded base configuration, the BASEconnection is common to both the input signal AND the output signal. The input signal is applied between the transistors base and the emitter terminals, while the corresponding output signal is taken from between the base and the collector terminals as shown. The base terminal is grounded or can be connected to some fixed reference voltage point. The input current flowing into the emitter is quite large as its the sum of both the base current and collector current respectively therefore, the collector current output is less than the emitter current input resulting in a current gain for this type of circuit of “1” (unity) or less, in other words the common base configuration “attenuates” the input signal.

    In the Common Emitteror grounded emitter configuration, the input signal is applied between the base and the emitter, while the output is taken from between the collector and the emitter as shown. This type of configuration is the most commonly used circuit for transistor based amplifiers and which represents the “normal” method of bipolar transistor connection. The common emitter amplifier configuration produces the highest current and power gain of all the three bipolar transistor configurations. This is mainly because the input impedance is LOW as it is connected to a forward biased PN-junction, while the output impedance is HIGH as it is taken from a reverse biased PN-junction.

    In the Common Collector or grounded collector configuration, the collector is connected to ground through the supply, thus the collector terminal is common to both the input and the output. The input signal is connected directly to the base terminal, while the output signal is taken from across the emitter load resistor as shown. This type of configuration is commonly known as a Voltage Follower or Emitter Followercircuit. The common collector, or emitter follower configuration is very useful for impedance matching applications because of its very high input impedance, in the region of hundreds of thousands of Ohms while having a relatively low output impedance.

    Then to summarise, the behaviour of the bipolar transistor in each one of the above circuit configurations is very different and produces different circuit characteristics with regards to input impedance, output impedance and gain whether this is voltage gain, current gain or power gain and this is summarised in the table below.

  9. Capacitor Types - Types of Capacitor » Electronics Notes › articles › electronic
    • Polar & non-polar
    • Leaded and Surface Mount Capacitors
    • Variable & Fixed Capacitors
    • Fixed Capacitor Types
    • Capacitor Types Overview

    One of the main distinctions between various types of capacitor is whether they are polarised. Essentially a polarised capacitor is one that must be run with the voltage across it in a certain polarity. Some of the more popular types of polarised capacitor include the aluminium electrolytic and tantalums. These are marked to indicate the positive or negative terminal and they should only be operated with a voltage bias int his direction - reverse bias can damage or destroy them. As capacitors perform many tasks like coupling and decoupling, there will be a permanent DC voltage across them, and they will pass only any AC components. The other form of capacitor is a non-polarised or non-polar capacitor. This type of capacitor has no polarity requirement and it can be connected either way in a circuit. Ceramic, plastic film, silver mica and a number of other capacitors are non-polar or non-polarised capacitors.

    Capacitors are available as leaded varieties and surface mount capacitors. Virtually all types of capacitor are available as leaded versions: electrolytic, ceramic, supercapacitors, plastic film, silver mica, glass and other specialist types. SMD capacitors are a little more limited. The SMD capacitors must be able to withstand the temperatures used in the soldering process. As the capacitor has no leads and also as a result of the soldering processes used, SMD components including capacitors are exposed tot he full temperature rise of the solder itself. As a result, not all varieties are available as SMD capacitors. The main surface mount capacitor types include: ceramic, tantalum, and electrolytic. All of these have been developed to withstand the very high temperatures of soldering.

    Another type distinction for capacitors is whether they are fixed or variable. The greatest majority of capacitors by far are fixed capacitors, i.e. they do not have any adjustment. However in some instances it may be necessary to have an adjustable or variable capacitor where the value of the capacitor may need to be varied. Typically these capacitors are relatively low in value, sometimes having maximum values up to 1000pF. Variable capacitors may also be classified as variable and preset. The main variable ones may be adjusted by a control knob and may be used for tuning a radio, etc. Preset variable capacitors normally have a screw adjustment and are intended to be adjusted during setup, calibration and test, etc. They are not intended to be adjusted in normal use.

    There are very many different fixed value capacitor types that can be bought and used in electronics circuits. These capacitors are generally categorised by the dielectric that is used within the capacitor as this governs the major properties: electrolytic, ceramic, silver mica, metallised plastic film and a number of others. While the list below gives some of the major capacitor types, not all can be listed and described and there are some less well used or less common types that can be seen. However it does include most of the major capacitor types. 1. Ceramic capacitor: As the name indicates, this type of capacitor gains its name from the fact that it uses a ceramic dielectric. This gives the many properties including a low loss factor, and a reasonable level of stability, but this depends upon the exact type of ceramic used. Ceramic dielectrics do not give as high a level of capacitance per unit volume as some types of capacitor and as a result ceramic capacitors typically range...

    It can be seen from even the selection of the most commonly used types of capacitor, that many forms are available. Each has its own advantages and disadvantages, and if the right one is chosen for each job, then it can perform very well in a circuit. It is for this reason when building circuits that it is important to use the right type of capacitor. If the wrong sort is used, then its performance many not be to the standard needed for the circuit. More Electronic Components: Resistors Capacitors Inductors Quartz crystals Diodes Transistor Phototransistor FET Memory types Thyristor Connectors RF connectors Valves / Tubes Batteries Switches Relays Return to Components menu . . .

  10. Review Sneak Peek: The Audio Note (UK) Io I MC Phono ... › review-sneak

    Jul 21, 2021 · Audio Note (UK) AN-S4L Level Four Step-Up Transformer ($7,542.72 USD) The Audio Note (UK) Io I moving-coil phonograph cartridge has a very low output of 0.04mV, so it requires the use of a step-up transformer for matching it to an Audio Note (UK) phono preamplifier to achieve adequate volume levels.

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