1.
Wire
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A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads or electricity and telecommunications signals, Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Wire gauges come in standard sizes, as expressed in terms of a gauge number. The term wire is used more loosely to refer to a bundle of such strands, as in multistranded wire. Wire comes in solid core, stranded, or braided forms, edge-wound coil springs, such as the Slinky toy, are made of special flattened wire. In some cases, strips cut from metal sheet were made into wire by pulling them through perforations in stone beads and this causes the strips to fold round on themselves to form thin tubes. This strip drawing technique was in use in Egypt by the 2nd Dynasty, from the middle of the 2nd millennium BCE most of the gold wires in jewellery are characterised by seam lines that follow a spiral path along the wire. Such twisted strips can be converted into solid round wires by rolling them between flat surfaces or the wire drawing method. The strip twist wire manufacturing method was superseded by drawing in the ancient Old World sometime between about the 8th and 10th centuries AD, there is some evidence for the use of drawing further East prior to this period. Square and hexagonal wires were made using a swaging technique. In this method a metal rod was struck between grooved metal blocks, or between a punch and a grooved metal anvil. Swaging is of great antiquity, possibly dating to the beginning of the 2nd millennium BCE in Egypt and in the Bronze and Iron Ages in Europe for torcs, twisted square-section wires are a very common filigree decoration in early Etruscan jewelry. In about the middle of the 2nd millennium BCE, a new category of decorative tube was introduced which imitated a line of granules. True beaded wire, produced by mechanically distorting a round-section wire, appeared in the Eastern Mediterranean and Italy in the seventh century BCE, a forerunner to beaded wire may be the notched strips and wires which first occur from around 2000 BCE in Anatolia. Wire was drawn in England from the medieval period, the wire was used to make wool cards and pins, manufactured goods whose import was prohibited by Edward IV in 1463. The first wire mill in Great Britain was established at Tintern in about 1568 by the founders of the Company of Mineral and Battery Works, apart from their second wire mill at nearby Whitebrook, there were no other wire mills before the second half of the 17th century. Despite the existence of mills, the drawing of wire down to fine sizes continued to be done manually. Wire is usually drawn of cylindrical form, but it may be made of any desired section by varying the outline of the holes in the draw-plate through which it is passed in the process of manufacture
2.
Electrical connector
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An electrical connector, is an electro-mechanical device used to join electrical terminations and create an electrical circuit. Electrical connectors consist of plugs and jacks, the connection may be temporary, as for portable equipment, require a tool for assembly and removal, or serve as a permanent electrical joint between two wires or devices. An adapter can be used to bring together dissimilar connectors. There are hundreds of types of electrical connectors, connectors may join two lengths of flexible copper wire or cable, or connect a wire or cable to an electrical terminal. In computing, a connector can also be known as a physical interface. Cable glands, known as cable connectors in the US, connect wires to devices rather than electrically and are distinct from quick-disconnects performing the latter. It is usually desirable for a connector to be easy to visually, rapid to assemble, require only simple tooling. In some cases an equipment manufacturer might choose a connector specifically because it is not compatible with those other sources. No single connector has all the properties, the proliferation of types is a reflection of differing requirements. Fretting is a failure mode in electrical connectors that have not been specifically designed to prevent it. Many connectors are keyed, with some mechanical component which prevents mating except with a correctly oriented matching connector, some connector housings are designed with locking mechanisms to prevent inadvertent disconnection or poor environmental sealing. Locking mechanism designs include locking levers of various sorts, screw locking, a terminal is a simple type of electrical connector that connects two or more wires to a single connection point. Wire nuts are another type of single point connector, terminal blocks provide a convenient means of connecting individual electrical wires without a splice or physically joining the ends. They are usually used to connect wiring among various items of equipment within an enclosure or to make connections among individually enclosed items. Since terminal blocks are available for a wide range of wire sizes and terminal quantity. One type of terminal block accepts wires that are prepared only by removing a short length of insulation from the end, another type accepts wires that have ring or spade terminal lugs crimped onto the wires. Printed circuit board mounted terminal blocks allow individual wires to be connected to the circuit board, a general type of connector that simply screws or clamps bare wire to a post, such connectors are frequently used in electronic test equipment and audio. Many, but not all binding posts will also accept a banana connector plug, since stripping the insulation from wires is time-consuming, many connectors intended for rapid assembly use insulation-displacement connectors so that insulation need not be removed from the wire
3.
Electronic test equipment
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Electronic test equipment is used to create signals and capture responses from electronic devices under test. In this way, the operation of the DUT can be proven or faults in the device can be traced. Use of electronic test equipment is essential to any work on electronics systems. ATE often includes many of instruments in real and simulated forms. Generally, more advanced test gear is necessary when developing circuits, designing a test system’s switching configuration requires an understanding of the signals to be switched and the tests to be performed, as well as the switching hardware form factors available. The following items are used for measurement of voltages, currents. Voltmeter Ohmmeter Ammeter, e. g. Galvanometer or Milliameter Multimeter e. g. VOM or DMM RLC Meter e. g and these systems are widely employed for incoming inspection, quality assurance, and production testing of electronic devices and subassemblies. The General Purpose Interface Bus is an IEEE-488 standard parallel interface used for attaching sensors, GPIB is a digital 8-bit parallel communications interface capable of achieving data transfers of more than 8 Mbytes/s. It allows daisy-chaining up to 14 instruments to a system using a 24-pin connector. It is one of the most common I/O interfaces present in instruments and is designed specifically for instrument control applications, the IEEE-488 specifications standardized this bus and defined its electrical, mechanical, and functional specifications, while also defining its basic software communication rules. GPIB works best for applications in industrial settings that require a connection for instrument control. The original GPIB standard was developed in the late 1960s by Hewlett-Packard to connect, the introduction of digital controllers and programmable test equipment created a need for a standard, high-speed interface for communication between instruments and controllers from various vendors. This standard was revised in 1978 and 1990. The IEEE488.2 specification includes the Standard Commands for Programmable Instrumentation, SCPI ensures compatibility and configurability among these instruments. The IEEE-488 bus has long been popular because it is simple to use and takes advantage of a selection of programmable instruments. Large systems, however, have the limitations, Driver fanout capacity limits the system to 14 devices plus a controller. Cable length limits the distance to two meters per device or 20 meters total, whichever is less. This imposes transmission problems on systems spread out in a room or on systems that require remote measurements, primary addresses limit the system to 30 devices with primary addresses
4.
Multimeter
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A multimeter or a multitester, also known as a VOM, is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter can measure voltage, current, and resistance, analog multimeters use a microammeter with a moving pointer to display readings. Digital multimeters have a display, and may also show a graphical bar representing the measured value. Digital multimeters are now far more due to their cost and precision. A multimeter can be a device useful for basic fault finding and field service work. Multimeters are available in a range of features and prices. Cheap multimeters can cost less than US$10, while models with certified calibration can cost more than US$5,000. The first moving-pointer current-detecting device was the galvanometer in 1820 and these were used to measure resistance and voltage by using a Wheatstone bridge, and comparing the unknown quantity to a reference voltage or resistance. While useful in the lab, the devices were very slow and these galvanometers were bulky and delicate. The DArsonval/Weston meter movement uses a coil which carries a pointer. The coil rotates in a permanent magnetic field and is restrained by fine spiral springs which also serve to carry current into the moving coil and it gives proportional measurement rather than just detection, and deflection is independent of the orientation of the meter. Instead of balancing a bridge, values could be read off the instruments scale. The basic moving coil meter is only for direct current measurements. It is easily adapted to read heavier currents by using shunts or to voltage using series resistances known as multipliers. To read alternating currents or voltages, a rectifier is needed, multimeters were invented in the early 1920s as radio receivers and other vacuum tube electronic devices became more common. Macadie invented an instrument which could measure amperes, volts and ohms, the meter comprised a moving coil meter, voltage and precision resistors, and switches and sockets to select the range. The Automatic Coil Winder and Electrical Equipment Company was set up to manufacture the Avometer, although a shareholder of ACWEECO, Mr MacAdie continued to work for the Post Office until his retirement in 1933. His son, Hugh S. MacAdie, joined ACWEECO in 1927, Automatic Coil Winder and Electrical Equipment Company
5.
Spring (device)
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A spring is an elastic object used to store mechanical energy. Springs are usually out of spring steel. There are a number of spring designs, in everyday usage the term often refers to coil springs. When a spring is compressed or stretched from its resting position, the rate or spring constant of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve, an extension or compression springs rate is expressed in units of force divided by distance, for example lbf/in or N/m. A torsion spring is a spring that works by twisting, when it is twisted about its axis by an angle, a torsion springs rate is in units of torque divided by angle, such as N·m/rad or ft·lbf/degree. The inverse of spring rate is compliance, that is, if a spring has a rate of 10 N/mm, the stiffness of springs in parallel is additive, as is the compliance of springs in series. Springs are made from a variety of materials, the most common being spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel, some non-ferrous metals are also used including phosphor bronze and titanium for parts requiring corrosion resistance and beryllium copper for springs carrying electrical current. Simple non-coiled springs were used throughout history, e. g. the bow. In the Bronze Age more sophisticated spring devices were used, as shown by the spread of tweezers in many cultures, coiled springs appeared early in the 15th century, in door locks. The first spring powered-clocks appeared in that century and evolved into the first large watches by the 16th century, in 1676 British physicist Robert Hooke discovered Hookes law which states that the force a spring exerts is proportional to its extension. Compression spring – is designed to operate with a compression load, flat spring – this type is made of a flat spring steel. Machined spring – this type of spring is manufactured by machining bar stock with a lathe and/or milling operation rather than a coiling operation, since it is machined, the spring may incorporate features in addition to the elastic element. Machined springs can be made in the load cases of compression/extension, torsion. Serpentine spring - a zig-zag of thick wire - often used in modern upholstery/furniture, the most common types of spring are, Cantilever spring – a spring which is fixed only at one end. Coil spring or helical spring – a spring is of two types, Tension or extension springs are designed to become longer under load and their turns are normally touching in the unloaded position, and they have a hook, eye or some other means of attachment at each end. Compression springs are designed to become shorter when loaded and their turns are not touching in the unloaded position, and they need no attachment points
6.
Banana
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The banana is an edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus Musa. In some countries, bananas used for cooking may be called plantains, in contrast to dessert bananas. The fruit is variable in size, color and firmness, but is elongated and curved, with soft flesh rich in starch covered with a rind which may be green, yellow, red, purple. The fruits grow in clusters hanging from the top of the plant, almost all modern edible parthenocarpic bananas come from two wild species – Musa acuminata and Musa balbisiana. The scientific names of most cultivated bananas are Musa acuminata, Musa balbisiana, the old scientific name Musa sapientum is no longer used. Musa species are native to tropical Indomalaya and Australia, and are likely to have been first domesticated in Papua New Guinea. They are grown in 135 countries, primarily for their fruit, worldwide, there is no sharp distinction between bananas and plantains. Especially in the Americas and Europe, banana usually refers to soft, sweet, dessert bananas, particularly those of the Cavendish group, by contrast, Musa cultivars with firmer, starchier fruit are called plantains. In other regions, such as Southeast Asia, many kinds of banana are grown and eaten. The term banana is used as the common name for the plants which produce the fruit. This can extend to members of the genus Musa like the scarlet banana, pink banana. It can also refer to members of the genus Ensete, like the snow banana, both genera are classified under the banana family, Musaceae. The banana plant is the largest herbaceous flowering plant, all the above-ground parts of a banana plant grow from a structure usually called a corm. Plants are normally tall and fairly sturdy, and are mistaken for trees. Bananas grow in a variety of soils, as long as the soil is at least 60 cm deep, has good drainage and is not compacted. The leaves of plants are composed of a stalk and a blade. The base of the petiole widens to form a sheath, the tightly packed sheaths make up the pseudostem, the edges of the sheath meet when it is first produced, making it tubular. As new growth occurs in the centre of the pseudostem the edges are forced apart, cultivated banana plants vary in height depending on the variety and growing conditions
7.
Screw
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A screw is a type of fastener, sometimes similar to a bolt, typically made of metal, and characterized by a helical ridge, known as a male thread or just thread. A screw is an inclined plane wrapped around a nail, some screw threads are designed to mate with a complementary thread, known as a female thread, often in the form of a nut or an object that has the internal thread formed into it. Other screw threads are designed to cut a groove in a softer material as the screw is inserted. The most common uses of screws are to hold objects together, a screw will usually have a head on one end that contains a specially formed shape that allows it to be turned, or driven, with a tool. Common tools for driving screws include screwdrivers and wrenches, the head is usually larger than the body of the screw, which keeps the screw from being driven deeper than the length of the screw and to provide a bearing surface. The cylindrical portion of the screw from the underside of the head to the tip is known as the shank, the distance between each thread is called the pitch. Another rule is this, curl the fingers of right hand around the screw with your thumb pointing is the direction you want the screw to go. If the screw is right-handed and you turn the screw in the direction of your fingers the screw will move in the direction of your thumb, Screws with left-hand threads are used in exceptional cases. For example, when the screw will be subject to counterclockwise torque, the right side pedal of a bicycle has a left-hand thread. More generally, screw may mean any helical device, such as a clamp, a micrometer, there is no universally accepted distinction between a screw and a bolt. So, as a rule, when buying a packet of screws you would not expect nuts to be included. Part of the confusion over this is due to regional or dialectical differences. An externally threaded fastener which is prevented from being turned during assembly, an externally threaded fastener that has thread form which prohibits assembly with a nut having a straight thread of multiple pitch length is a screw. This distinction is consistent with ASME B18.2.1 and some dictionary definitions for screw, some of these issues are discussed below, ASME standards specify a variety of Machine Screws in diameters ranging up to 0.75 in. These fasteners are used with nuts but also often driven into tapped holes. They might be considered a screw or a bolt based on the Machinerys Handbook distinction, ASME standard B18.2. 1-1996 specifies Hex Cap Screws that range in size from 0. 25–3 in in diameter. These fasteners are very similar to hex bolts and they differ mostly in that they are manufactured to tighter tolerances than the corresponding bolts. Machinerys Handbook refers parenthetically to these fasteners as Finished Hex Bolts, in 1991 responding to an influx of counterfeit fasteners Congress passed PL 101-592 Fastener Quality Act This resulted in the rewriting of specifications by the ASME B18 committee
8.
Solder
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Solder is a fusible metal alloy used to create a permanent bond between metal workpieces. The word solder comes from the Middle English word soudur, via Old French solduree and soulder, from the Latin solidare, meaning to make solid. In fact, solder must be melted in order to adhere to and connect the pieces together, whenever possible, the solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder that is intended for use in making connections between electronic components also usually has favorable electrical characteristics. Soft solder typically has a melting point range of 90 to 450 °C, and is used in electronics, plumbing. Manual soldering uses an iron or soldering gun. Alloys that melt between 180 and 190 °C are the most commonly used, soldering performed using alloys with a melting point above 450 °C is called hard soldering, silver soldering, or brazing. In specific proportions, some alloys can become eutectic — that is, non-eutectic alloys have markedly different solidus and liquidus temperatures, and within that range they exist as a paste of solid particles in a melt of the lower-melting phase. In electrical work, if the joint is disturbed in the pasty state before it has solidified totally, for electrical and electronics work, solder wire is available in a range of thicknesses for hand-soldering, and with cores containing flux. It is also available as a paste or as a preformed foil shaped to match the workpiece, alloys of lead and tin were commonly used in the past, and are still available, they are particularly convenient for hand-soldering. Lead-free solders have been increasing in use due to regulatory requirements plus the health and they are almost exclusively used today in consumer electronics. Plumbers often use bars of solder, much thicker than the used for electrical applications. Jewelers often use solder in thin sheets, which cut into snippets. In the US, manufacturers may receive tax benefits by reducing the use of lead-based solder, lead-free solders in commercial use may contain tin, copper, silver, bismuth, indium, zinc, antimony, and traces of other metals. Most lead-free replacements for conventional 60/40 and 63/37 Sn-Pb solder have melting points from 5 to 20 °C higher and it may be desirable to use minor modification of the solder pots used in wave-soldering, to reduce maintenance cost due to increased tin-scavenging of high-tin solder. Lead-free solder may be desirable for critical applications, such as aerospace and medical projects. Tin-Silver-Copper solders are used by two-thirds of Japanese manufacturers for reflow and wave soldering, tin-based solders readily dissolve gold, forming brittle intermetallics, for Sn-Pb alloys the critical concentration of gold to embrittle the joint is about 4%. Indium-rich solders are more suitable for soldering thicker gold layer as the rate of gold in indium is much slower
9.
Insulator (electricity)
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An electrical insulator is a material whose internal electric charges do not flow freely, very little electric current will flow through it under the influence of an electric field. This contrasts with other materials, semiconductors and conductors, which conduct electric current more easily, the property that distinguishes an insulator is its resistivity, insulators have higher resistivity than semiconductors or conductors. A perfect insulator does not exist, because even insulators contain small numbers of mobile charges which can carry current, in addition, all insulators become electrically conductive when a sufficiently large voltage is applied that the electric field tears electrons away from the atoms. This is known as the voltage of an insulator. Some materials such as glass, paper and Teflon, which have high resistivity, are good electrical insulators. Examples include rubber-like polymers and most plastics which can be thermoset or thermoplastic in nature, insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves. An insulating material used in bulk to wrap electrical cables or other equipment is called insulation, the term insulator is also used more specifically to refer to insulating supports used to attach electric power distribution or transmission lines to utility poles and transmission towers. They support the weight of the suspended wires without allowing the current to flow through the tower to ground, electrical insulation is the absence of electrical conduction. Electronic band theory says that a charge flows if states are available into which electrons can be excited and this allows electrons to gain energy and thereby move through a conductor such as a metal. If no such states are available, the material is an insulator, most insulators have a large band gap. This occurs because the valence band containing the highest energy electrons is full, there is always some voltage that gives electrons enough energy to be excited into this band. Once this voltage is exceeded the material ceases being an insulator, however, it is usually accompanied by physical or chemical changes that permanently degrade the materials insulating properties. Materials that lack electron conduction are insulators if they lack other mobile charges as well, for example, if a liquid or gas contains ions, then the ions can be made to flow as an electric current, and the material is a conductor. Electrolytes and plasmas contain ions and act as conductors whether or not electron flow is involved, when subjected to a high enough voltage, insulators suffer from the phenomenon of electrical breakdown. These freed electrons and ions are in turn accelerated and strike other atoms, creating more charge carriers, rapidly the insulator becomes filled with mobile charge carriers, and its resistance drops to a low level. In a solid, the voltage is proportional to the band gap energy. The air in a region around a conductor can break down and ionise without a catastrophic increase in current. Even a vacuum can suffer a sort of breakdown, but in case the breakdown or vacuum arc involves charges ejected from the surface of metal electrodes rather than produced by the vacuum itself
