1.
International Electrotechnical Commission
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The IEC also manages three global conformity assessment systems that certify whether equipment, system or components conform to its International Standards. The first International Electrical Congress took place in 1881 at the International Exposition of Electricity, at that time the International System of Electrical and Magnetic Units was agreed to. The IEC was instrumental in developing and distributing standards for units of measurement, particularly Gauss, Hertz and it also first proposed a system of standards, the Giorgi System, which ultimately became the SI, or Système International d’unités. In 1938, it published a multilingual international vocabulary to unify terminology relating to electrical, electronic and this effort continues, and the International Electrotechnical Vocabulary remains an important work in the electrical and electronic industries. The CISPR – in English, the International Special Committee on Radio Interference – is one of the groups founded by the IEC, originally located in London, the commission moved to its current headquarters in Geneva in 1948. It has regional centres in Asia-Pacific, Latin America and North America, today, the IEC is the worlds leading international organization in its field, and its standards are adopted as national standards by its members. The work is done by some 10,000 electrical and electronics experts from industry, government, academia, test labs, IEC standards have numbers in the range 60000–79999 and their titles take a form such as IEC60417, Graphical symbols for use on equipment. Following the Dresden Agreement with CENELEC the numbers of older IEC standards were converted in 1997 by adding 60000, for example IEC27 became IEC60027. Standards of the 60000 series are also preceded by EN to indicate that the IEC standard is also adopted by CENELEC as a European standard. The IEC cooperates closely with the International Organization for Standardization and the International Telecommunication Union, Standards developed jointly with ISO such as ISO/IEC26300, ISO/IEC27001, and CASCO ISO/IEC17000 series, carry the acronym of both organizations. The use of the ISO/IEC prefix covers publications from ISO/IEC Joint Technical Committee 1 - Information Technology, as well as conformity assessment standards developed by ISO CASCO, other standards developed in cooperation between IEC and ISO are assigned numbers in the 80000 series, such as IEC 82045-1. IEC standards are also being adopted by other certifying bodies such as BSI, CSA, UL & ANSI/INCITS, SABS, SAI, SPC/GB, IEC standards adopted by other certifying bodies may have some noted differences from the original IEC standard. The IEC is made up of members, called national committees, national committees are constituted in different ways. Some NCs are public sector only, some are a combination of public and private sector, about 90% of those who prepare IEC standards work in industry
2.
Battery (electricity)
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An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, smartphones, and electric cars. When a battery is supplying power, its positive terminal is the cathode. The terminal marked negative is the source of electrons that when connected to a circuit will flow. It is the movement of ions within the battery which allows current to flow out of the battery to perform work. Historically the term specifically referred to a device composed of multiple cells. Primary batteries are used once and discarded, the materials are irreversibly changed during discharge. Common examples are the battery used for flashlights and a multitude of portable electronic devices. Secondary batteries can be discharged and recharged multiple times using mains power from a wall socket, examples include the lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as laptops and smartphones. According to a 2005 estimate, the battery industry generates US$48 billion in sales each year. Batteries have much lower energy than common fuels such as gasoline. This is somewhat offset by the efficiency of electric motors in producing mechanical work. The usage of battery to describe a group of electrical devices dates to Benjamin Franklin, alessandro Volta built and described the first electrochemical battery, the voltaic pile, in 1800. This was a stack of copper and zinc plates, separated by brine-soaked paper disks, Volta did not understand that the voltage was due to chemical reactions. Although early batteries were of value for experimental purposes, in practice their voltages fluctuated. It consisted of a pot filled with a copper sulfate solution, in which was immersed an unglazed earthenware container filled with sulfuric acid. These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly, many used glass jars to hold their components, which made them fragile and potentially dangerous. These characteristics made wet cells unsuitable for portable appliances, near the end of the nineteenth century, the invention of dry cell batteries, which replaced the liquid electrolyte with a paste, made portable electrical devices practical. Batteries convert chemical energy directly to electrical energy, a battery consists of some number of voltaic cells
3.
Flashlight
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A flashlight or a torch, is a portable hand-held electric light. The source of the light is usually an incandescent light bulb or light-emitting diode, a typical flashlight consists of a light bulb mounted in a reflector, a transparent cover to protect the light source and reflector, a battery, and a switch. These are supported and protected by a case, the invention of the dry cell and miniature incandescent electric light bulbs made the first battery-powered flashlights possible around 1899. Today flashlights use mostly incandescent lamps or light-emitting diodes and run on disposable or rechargeable batteries, some are powered by the user turning a crank or shaking the lamp, and some have solar panels to recharge a battery. In addition to the general-purpose hand-held flashlight, many forms have been adapted for special uses, head or helmet-mounted flashlights designed for miners and campers leave the hands free. Some flashlights can be used underwater or in flammable atmospheres, flashlights are used as a light source when in a place with no power. Early flashlights ran on batteries, which could not provide a steady electric current. Because these early flashlights also used energy-inefficient carbon-filament bulbs, resting occurred at short intervals, consequently, they could be used only in brief flashes, hence the common North American name flashlight. The first dry cell battery was invented in 1887, unlike previous batteries, it used a paste electrolyte instead of a liquid. This was the first battery suitable for electrical devices, as it did not spill or break easily. The first mass-produced dry cell batteries came in 1896, and the invention of electric lights soon followed. Portable hand-held electric lights offered advantages in convenience and safety over torches, candles, the electric lamp was odorless, smokeless, and emitted less heat than combustion-powered lighting. It could be turned on and off, and avoided fire risk. On January 10,1899, British inventor David Misell obtained U. S,617,592, assigned to American Electrical Novelty and Manufacturing Company. This electric device designed by Misell was powered by D batteries laid front to back in a tube with the light bulb. The company donated some of these devices to the New York City police, carbon-filament bulbs and fairly crude dry cells made early flashlights an expensive novelty with low sales and low manufacturer interest. Development of the tungsten-filament lamp in 1904, with three times the efficacy of carbon filament types, and improved batteries, made flashlights more useful and popular. The advantage of instant control, and the absence of flame, flashlights became very popular in China, by the end of the 1930s,60 companies made flashlights, some selling for as little as one-third the cost of equivalent imported models
4.
Radio receiver
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In radio communications, a radio receiver is an electronic device that receives radio waves and converts the information carried by them to a usable form. It is used with an antenna, the antenna intercepts radio waves and converts them to tiny alternating currents which are applied to the receiver, and the receiver extracts the desired information. The information produced by the receiver may be in the form of sound, a radio receiver may be a separate piece of electronic equipment, or an electronic circuit within another device. The most familiar form of radio receiver is a broadcast receiver, often just called a radio, the sound is produced either by a loudspeaker in the radio or an earphone which plugs into a jack on the radio. The radio requires electric power, provided either by batteries inside the radio or a cord which plugs into an electric outlet. All radios have a control to adjust the loudness of the audio. The frequency of radio stations is usually listed prominently in their advertising, in order to select a particular station to receive, the radio is adjusted to the frequency of the desired transmitter. In some radios this is done by the user turning a tuning knob until the station is heard in the radios loudspeaker. In most countries radio broadcasting is permitted using two different methods of modulation, that is, methods of adding the signal to the radio wave, AM and FM. In amplitude modulation the strength of the signal is varied by the audio signal. AM broadcasting is permitted on AM broadcast bands between 148 and 283 kHz in the low range and 526 and 1706 kHz in the medium frequency range of the radio spectrum. In frequency modulation the frequency of the signal is varied slightly by the audio signal. FM broadcasting is permitted in the FM broadcast bands between about 65 and 108 MHz in the high frequency range. The exact frequency ranges vary somewhat in different countries, radios sold in each receive the correct frequency range for that country. Most broadcast radios, called AM/FM radios, can receive both AM and FM bands, and have a switch to select which band to receive. Limited AM broadcasting is permitted in parts of the high frequency band called the shortwave band. Shortwave listening requires a receiver that can receive these bands, called a shortwave receiver, at these frequencies, radio waves transmitted into the sky can reflect from a layer in the atmosphere called the ionosphere, returning to earth at transcontinental distances. So shortwaves are used for long distance international broadcasting, often by governmental public service broadcasting organizations like the BBC, due to their lower frequency, AM radio stations can often be received at longer distances than FM stations, at hundreds of miles
5.
Transmitter
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In electronics and telecommunications a transmitter or radio transmitter is an electronic device which generates a radio frequency alternating current. When a connected antenna is excited by this current, the antenna emits radio waves. The term transmitter is usually limited to equipment that generates radio waves for communication purposes, or radiolocation, such as radar and navigational transmitters. Generators of radio waves for heating or industrial purposes, such as ovens or diathermy equipment, are not usually called transmitters even though they often have similar circuits. The term is used more specifically to refer to a broadcast transmitter. This usage typically includes both the proper, the antenna, and often the building it is housed in. A transmitter can be a piece of electronic equipment, or an electrical circuit within another electronic device. A transmitter and a receiver combined in one unit is called a transceiver, the term transmitter is often abbreviated XMTR or TX in technical documents. The purpose of most transmitters is radio communication of information over a distance, the transmitter combines the information signal to be carried with the radio frequency signal which generates the radio waves, which is called the carrier signal. The information can be added to the carrier in several different ways, in an amplitude modulation transmitter, the information is added to the radio signal by varying its amplitude. In a frequency modulation transmitter, it is added by varying the signals frequency slightly. Many other types of modulation are used, the radio signal from the transmitter is applied to the antenna, which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as phones, walkie-talkies. In more powerful transmitters, the antenna may be located on top of a building or on a tower, and connected to the transmitter by a feed line. The first primitive radio transmitters were built by German physicist Heinrich Hertz in 1887 during his investigations of radio waves. These generated radio waves by a high voltage spark between two conductors, beginning in 1895 Guglielmo Marconi developed the first practical radio communication systems using spark transmitters. These spark-gap transmitters were used during the first three decades of radio, called the wireless telegraphy or spark era, vacuum tube transmitters took over because they were inexpensive and produced continuous waves, which could be modulated to transmit audio using amplitude modulation. This made possible commercial AM radio broadcasting, which began in about 1920, experimental television transmission had been conducted by radio stations since the late 1920s, but practical television broadcasting didnt begin until the 1940s
6.
Boombox
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Boombox is a common term for a portable transistorized cassette tape recorder/player and AM/FM radio with an amplifier, two or more loudspeakers and a carrying handle. A boombox is a device capable of receiving radio stations. Many models are capable of recording onto cassette tapes from radio. Designed for portability, boomboxes can be powered by batteries as well as by line current, the boombox was introduced to the American market during the mid-1970s. The desire for louder and heavier bass led to bigger and heavier boxes, by the 1980s, most boomboxes were battery-operated, leading to extremely heavy, bulky boxes. The boombox quickly became associated with society in the United States, particularly African American. Cities petitioned for the banning of boomboxes from public places, the boombox became closely linked to American hip hop culture and was instrumental in the rise of hip hop music. The first boombox was developed by the inventor of the compact cassette. Their first Radiorecorder was released in 1966, the Philips innovation was the first time that radio broadcasts could be recorded onto cassette tapes without the cables or microphones that previous stand-alone cassette tape recorders required. Although sound quality of tape recordings was poor, improvements in technology and the introduction of stereo recording, chromium tapes. Several European electronics brands, such as Grundig, also introduced similar devices, boomboxes were soon also developed in Japan in the early 1970s and became popular there due to their compact size and impressive sound quality. The Japanese brands soon took over a portion of the European boombox market and were often the first Japanese consumer electronics brands that a European household might purchase. The Japanese innovated by creating different sizes, form factors, and technology, introducing such advances as stereo boomboxes, removable speakers, in-built TV receivers, and inbuilt CD players. The boombox was introduced to the American market during the mid-1970s, with the bulk of production being carried out by Panasonic, Sony, Marantz, and General Electric. It was immediately noticed by the urban adolescent community and soon had a market, especially in metropolitan centers such as New York, Los Angeles. The development of audio jacks brought the boombox to the height of its popularity, consumers enjoyed the portability and sound quality of boomboxes, but one of the most important features, especially to the youth market, was the bass. The desire for louder and heavier bass led to bigger and heavier boxes, most units can be powered by AC or DC cables in addition to batteries. As boomboxes grew in popularity, they became more complex in design
7.
Electric motor
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An electric motor is an electrical machine that converts electrical energy into mechanical energy. The reverse of this is the conversion of energy into electrical energy and is done by an electric generator. In normal motoring mode, most electric motors operate through the interaction between an electric motors magnetic field and winding currents to generate force within the motor, small motors may be found in electric watches. General-purpose motors with highly standardized dimensions and characteristics provide convenient mechanical power for industrial use, the largest of electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors may be classified by electric power source type, internal construction, application, type of motion output, perhaps the first electric motors were simple electrostatic devices created by the Scottish monk Andrew Gordon in the 1740s. The theoretical principle behind production of force by the interactions of an electric current. The conversion of energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821. A free-hanging wire was dipped into a pool of mercury, on which a permanent magnet was placed, when a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a close circular magnetic field around the wire. This motor is often demonstrated in experiments, brine substituting for toxic mercury. Though Barlows wheel was a refinement to this Faraday demonstration. In 1827, Hungarian physicist Ányos Jedlik started experimenting with electromagnetic coils, after Jedlik solved the technical problems of the continuous rotation with the invention of the commutator, he called his early devices electromagnetic self-rotors. Although they were used only for instructional purposes, in 1828 Jedlik demonstrated the first device to contain the three components of practical DC motors, the stator, rotor and commutator. The device employed no permanent magnets, as the fields of both the stationary and revolving components were produced solely by the currents flowing through their windings. His motor set a record which was improved only four years later in September 1838 by Jacobi himself. His second motor was powerful enough to drive a boat with 14 people across a wide river and it was not until 1839/40 that other developers worldwide managed to build motors of similar and later also of higher performance. The first commutator DC electric motor capable of turning machinery was invented by the British scientist William Sturgeon in 1832, following Sturgeons work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American inventor Thomas Davenport, which he patented in 1837. The motors ran at up to 600 revolutions per minute, and powered machine tools, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same battery power cost issues, no electricity distribution had been developed at the time
8.
Geiger counter
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It detects ionizing radiation such as alpha particles, beta particles and gamma rays using the ionization effect produced in a Geiger–Müller tube, which gives its name to the instrument. In wide and prominent use as a radiation survey instrument. Since then it has very popular due to its robust sensing element. However, there are limitations in measuring high radiation rates and the energy of incident radiation, a Geiger counter consists of a Geiger-Müller tube, the sensing element which detects the radiation, and the processing electronics, which displays the result. The Geiger-Müller tube is filled with a gas such as helium, neon, or argon at low pressure. The tube briefly conducts electrical charge when a particle or photon of incident radiation makes the gas conductive by ionization, the ionization is considerably amplified within the tube by the Townsend discharge effect to produce an easily measured detection pulse, which is fed to the processing and display electronics. This large pulse from the tube makes the G-M counter relatively cheap to manufacture, the electronics also generates the high voltage, typically 400–600 volts, that has to be applied to the Geiger-Müller tube to enable its operation. There are two types of radiation readout, counts or radiation dose, the counts display is the simplest and is the number of ionizing events displayed either as a count rate, commonly counts per second, or as a total over a set time period. The counts readout is normally used when alpha or beta particles are being detected, more complex to achieve is a display of radiation dose rate, displayed in a unit such as the sievert which is normally used for measuring gamma or X-ray dose rates. A G-M tube can detect the presence of radiation, but not its energy influences the radiations ionising effect. Consequently, instruments measuring dose rate require the use of an energy compensated G-M tube, the electronics will apply known factors to make this conversion, which is specific to each instrument and is determined by design and calibration. The readout can be analog or digital, and increasingly, modern instruments are offering serial communications with a host computer or network, there is usually an option to produce audible clicks representing the number of ionization events detected. This is the distinctive sound associated with hand held or portable Geiger counters. The purpose of this is to allow the user to concentrate on manipulation of the instrument whilst retaining auditory feedback on the radiation rate, there are two main limitations of the Geiger counter. Because the output pulse from a Geiger-Müller tube is always the same regardless of the energy of the incident radiation. A further limitation is the inability to measure radiation rates due to the dead time of the tube. This is a period after each ionization of the gas during which any further incident radiation will not result in a count. Typically the dead time will reduce indicated count rates above about 104 to 105 counts per second depending on the characteristic of the tube being used, whilst some counters have circuitry which can compensate for this, for accurate measurements ion chamber instruments are preferred for high radiation rates
9.
Megaphone
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A megaphone, speaking-trumpet, bullhorn, or loud hailer is a portable, usually hand-held, cone-shaped acoustic horn used to amplify a person’s voice or other sounds and direct it in a given direction. The sound is introduced into the end of the megaphone, by holding it up to the face and speaking into it. The megaphone increases the volume of sound by increasing the acoustic impedance seen by the cords, matching the impedance of the vocal cords to the air. It also serves to direct the waves in the direction the horn is pointing. It somewhat distorts the sound of the voice because the response of the megaphone is greater at higher sound frequencies. Since the 1960s the voice-powered acoustic megaphone described above has been replaced by the electric megaphone, the initial inventor of the speaking trumpet is a subject of historical controversy, both Samuel Morland and Athanasius Kircher invented megaphones around the same time in the 17th century. Morland, in a work published in 1655, wrote about his experimentation with different horns and his largest megaphone consisted of over 20 feet of copper tube and could reportedly project a persons voice a mile and a half. Twenty years earlier, Kircher described a device that could be used as both a megaphone and for overhearing people speaking outside a house. His coiled horn would be mounted into the side of a building, with a narrow end inside that could be spoken into or listened to. Morland favored a straight, tube-shaped speaking device, kircher’s horn, on the other hand, utilized a “cochleate” design, where the horn was twisted and coiled to make it more compact. A later, papier-mache trumpet of special design was the Sengerphone, additionally, in ruins of Tiwanaku are stones around the central place with holes shaped in megaphones profile. Their purpose is unknown, but as local guards can show. The term ‘megaphone’ was first associated with Thomas Edison’s instrument 200 years later, in 1878, Edison developed a device similar to the speaking trumpet in hopes of benefiting the deaf and hard of hearing. His variation included three separate funnels lined up in a row, the two outer funnels, which were six feet and eight inches long, were made of paper and connected to a tube inserted in each ear. The middle funnel was similar to Morland’s speaking trumpet, but had a slot to insert a user’s mouth. With Edison’s megaphone, a low whisper could be heard a thousand feet away, on the listening end, the receiver could hear a low whisper at a thousand feet away. However the apparatus was much too large to be portable, limiting its use, george Prescott wrote, “The principal drawback at present is the large size of the apparatus. An electric megaphone is a public address system, an electronic device that amplifies the human voice like an acoustic megaphone
10.
Rechargeable battery
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It is composed of one or more electrochemical cells. The term accumulator is used as it accumulates and stores energy through an electrochemical reaction. Rechargeable batteries are produced in different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of materials and electrolytes are used, including lead–acid, nickel cadmium, nickel metal hydride, lithium ion. Some rechargeable battery types are available in the sizes and voltages as disposable types. Devices which use rechargeable batteries include automobile starters, portable devices, light vehicles, tools, uninterruptible power supplies. Emerging applications in hybrid internal combustion-battery and electric vehicles drive the technology to reduce cost, weight, and size, Battery storage power stations use rechargeable batteries for load-leveling and for renewable energy uses. Load-leveling reduces the power which a plant must be able to generate, reducing capital cost. The US National Electrical Manufacturers Association estimated in 2006 that US demand for batteries was growing twice as fast as demand for disposables. Small rechargeable batteries can power portable devices, power tools, appliances. Heavy-duty batteries power electric vehicles, ranging from scooters to locomotives and they are used in distributed electricity generation and in stand-alone power systems. During charging, the active material is oxidized, producing electrons. These electrons constitute the current flow in the external circuit, the energy used to charge rechargeable batteries usually comes from a battery charger using AC mains electricity, although some are equipped to use a vehicles 12-volt DC power outlet. Regardless, to energy in a secondary cell, it has to be connected to a DC voltage source. The negative terminal of the cell has to be connected to the terminal of the voltage source. Chargers take from a few minutes to several hours to charge a battery, slow dumb chargers without voltage or temperature-sensing capabilities will charge at a low rate, typically taking 14 hours or more to reach a full charge. Rapid chargers can typically charge cells in two to five hours, depending on the model, with the fastest taking as little as fifteen minutes, fast chargers must have multiple ways of detecting when a cell reaches full charge to stop charging before harmful overcharging or overheating occurs. The fastest chargers often incorporate cooling fans to keep the cells from overheating, Battery charging and discharging rates are often discussed by referencing a C rate of current
