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Tesla Coil
A Tesla coil is an electrical resonant transformer circuit designed by inventor Nikola Tesla in 1891. It is used to produce high-voltage, low- current, high-frequency alternating-current electricity. Tesla experimented with a number of different configurations consisting of two, or sometimes three, coupled resonant electric circuits. Tesla used these circuits to conduct innovative experiments in electrical lighting, phosphorescence, X-ray generation, high-frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires. Tesla coil circuits were used commercially in spark-gap radio transmitters for wireless telegraphy until the 1920s, and in medical equipment such as electrotherapy and violet ray devices. Today, their main usage is for entertainment and educational displays, although small coils are still used as leak detectors for high-vacuum systems. Originally, Tesla coils used fixed spark gaps or rotary spark gaps to provi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Questacon
Questacon – The National Science and Technology Centre is an interactive science communication facility in Canberra, Australia. It is a museum with more than 200 interactive exhibits relating to science and technology. It has many science programs that are intended to inspire the children of Australia to love science. Complementing the main museum, Questacon Science Circus is an extensive science outreach program. Each year, the Science Circus engages with more than 100,000 people, travels 25,000 kilometers, runs professional development courses for 600 teachers, and visits about 30 remote aboriginal communities as well as hospitals, nursing homes, and special schools. History Questacon is an interactive science centre that began as a project of the Australian National University (ANU), in spare space at the Ainslie Public School in Canberra. It opened with 15 exhibits and was staffed entirely by volunteers and by ANU physics lecturer Professor Mike Gore AM, it inspire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Frequency
High frequency (HF) is the ITU designation for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one hundred meters). Frequencies immediately below HF are denoted medium frequency (MF), while the next band of higher frequencies is known as the very high frequency (VHF) band. The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or " skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances and for mountainous terrains which prevent line-of-sight communications. The band is used by international shortwave broadcasting station ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vacuum Tube
A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplification and current rectification. Non-thermionic types such as a vacuum phototube, however, achieve electron emission through the photoelectric effect, and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve), invented in 1904 by John Ambrose Fleming, contains only a heated electron-emitting cathode and an anode. Electrons can only flow in one direction through the device—from the cathode to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyristor
A thyristor () is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts exclusively as a bistable switch (or a latch), conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reversed biased, or until the voltage is removed (by some other means). There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its Gate lead controls the larger current of the Anode to Cathode path. In a two-lead thyristor, conduction begins when the potential difference between the Anode and Cathode themselves is sufficiently large (breakdown voltage). Some sources define silicon-controlled rectifier (SCR) and thyristor as synonymous. Other sources define thyristors as more complex devices that incorporate at least four layers of alternating N-type and P-type substrate. The first thyristor devices were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transistor
upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electrical power, power. The transistor is one of the basic building blocks of modern electronics. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more are found embedded in integrated circuits. Austro-Hungarian physicist Julius Edgar Lilienfeld proposed the concept of a field-effect transistor in 1926, but it was not possible to actually cons ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spark Gap
A spark gap consists of an arrangement of two conducting electrodes separated by a gap usually filled with a gas such as air, designed to allow an electric spark to pass between the conductors. When the potential difference between the conductors exceeds the breakdown voltage of the gas within the gap, a spark forms, ionizing the gas and drastically reducing its electrical resistance. An electric current then flows until the path of ionized gas is broken or the current reduces below a minimum value called the "holding current". This usually happens when the voltage drops, but in some cases occurs when the heated gas rises, stretching out and then breaking the filament of ionized gas. Usually, the action of ionizing the gas is violent and disruptive, often leading to sound (ranging from a ''snap'' for a spark plug to thunder for a lightning discharge), light and heat. Spark gaps were used historically in early electrical equipment, such as spark gap radio transmitters, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Resonant Inductive Coupling
Resonant inductive coupling or magnetic phase synchronous coupling is a phenomenon with inductive coupling where the coupling becomes stronger when the "secondary" (load-bearing) side of the loosely coupled coil resonates. A resonant transformer of this type is often used in analog circuitry as a bandpass filter. Resonant inductive coupling is also used in wireless power systems for portable computers, phones, and vehicles. Applications Various resonant coupling systems in use or are under development for short range (up to 2 meters) wireless electricity systems to power laptops, tablets, smartphones, robot vacuums, implanted medical devices, and vehicles like electric cars, SCMaglev trains and automated guided vehicles.10 kW) of resonant inductive energy transfer. High power levels are required for rapid recharging and high energy transfer efficiency is required both for operational economy and to avoid negative environmental impact of the system. An experimental e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronic Oscillator
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave or a triangle wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal. They are widely used in many electronic devices ranging from simplest clock generators to digital instruments (like calculators) and complex computers and peripherals etc. Common examples of signals generated by oscillators include signals broadcast by radio and television transmitters, clock signals that regulate computers and quartz clocks, and the sounds produced by electronic beepers and video games. Oscillators are often characterized by the frequency of their output signal: *A low-frequency oscillator (LFO) is an electronic oscillator that generates a frequency below approximately 20 Hz. This term is typically used in the field of audio synthesizers, to distinguish it from an audio frequency oscillator ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radio Frequency
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range. Electric current Electric currents that oscillate at radio frequencies (RF currents) have special properties not shared by direct current or lower audio frequency alternating current, such as the 50 or 60 Hz current used in electrical power distribution. * Energy from RF currents in conductors can radiate into space as electromagnetic waves ( radio waves). This is the basis of radio technology. * RF current does not penetrate deeply into electri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Violet Ray
A violet ray is an antique medical appliance used during the early 20th century to discharge in electrotherapy. Their construction usually featured a disruptive discharge coil with an interrupter to apply a high voltage, high frequency, low current to the human body for therapeutic purposes. Overview Nikola Tesla introduced his first prototype violet ray at the World's Columbian Exposition in 1893. Most of the antique violet rays in the US were produced before the Depression era, and some of the larger US manufacturers of violet rays were Renulife, Fitzgerald, and Fisher. Companies who manufactured violet ray devices made many other types of electrical appliances as well, e.g. Star Electric, which also manufactured stock ticker machines. Many of the companies who were able to continue manufacturing violet rays after the Depression stopped making them due to World War II, when they began manufacturing radio coils and other electrical components for the war instead. A typical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wireless Telegraphy
Wireless telegraphy or radiotelegraphy is transmission of text messages by radio waves, analogous to electrical telegraphy using cables. Before about 1910, the term ''wireless telegraphy'' was also used for other experimental technologies for transmitting telegraph signals without wires. In radiotelegraphy, information is transmitted by pulses of radio waves of two different lengths called "dots" and "dashes", which spell out text messages, usually in Morse code. In a manual system, the sending operator taps on a switch called a telegraph key which turns the transmitter on and off, producing the pulses of radio waves. At the receiver the pulses are audible in the receiver's speaker as beeps, which are translated back to text by an operator who knows Morse code. Radiotelegraphy was the first means of radio communication. The first practical radio transmitters and receivers invented in 1894–1895 by Guglielmo Marconi used radiotelegraphy. It continued to be the only type ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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