A power supply is an electrical device that supplies electric power to an electrical load. The primary function of a power supply is to convert electric current from a source to the correct voltage and frequency to power the load; as a result, power supplies are sometimes referred to as electric power converters. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. Examples of the latter include power supplies found in desktop computers and consumer electronics devices. Other functions that power supplies may perform include limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, storing energy so it can continue to power the load in the event of a temporary interruption in the source power. All power supplies have a power input connection, which receives energy in the form of electric current from a source, one or more power output connections that deliver current to the load.
The source power may come from the electric power grid, such as an electrical outlet, energy storage devices such as batteries or fuel cells, generators or alternators, solar power converters, or another power supply. The input and output are hardwired circuit connections, though some power supplies employ wireless energy transfer to power their loads without wired connections; some power supplies have other types of inputs and outputs as well, for functions such as external monitoring and control. Power supplies are categorized including by functional features. For example, a regulated power supply is one that maintains constant output voltage or current despite variations in load current or input voltage. Conversely, the output of an unregulated power supply can change when its input voltage or load current changes. Adjustable power supplies allow the output voltage or current to be programmed by mechanical controls, or by means of a control input, or both. An adjustable regulated power supply is one, both adjustable and regulated.
An isolated power supply has a power output, electrically independent of its power input. Power supplies are classified accordingly. A bench power supply is a stand-alone desktop unit used in applications such as circuit test and development. Open frame power supplies have only a partial mechanical enclosure, sometimes consisting of only a mounting base. Rack mount. An integrated power supply is one. An external power supply, AC adapter or power brick, is a power supply located in the load's AC power cord that plugs into a wall outlet; these are popular in consumer electronics because of their safety. Power supplies can be broadly divided into linear and switching types. Linear power converters process the input power directly, with all active power conversion components operating in their linear operating regions. In switching power converters, the input power is converted to AC or to DC pulses before processing, by components that operate predominantly in non-linear modes. Power is "lost" when components operate in their linear regions and switching converters are more efficient than linear converters because their components spend less time in linear operating regions.
A DC power supply is one. Depending on its design, a DC power supply may be powered from a DC source or from an AC source such as the power mains. DC power supplies use AC mains electricity as an energy source; such power supplies will employ a transformer to convert the input voltage to a higher or lower AC voltage. A rectifier is used to convert the transformer output voltage to a varying DC voltage, which in turn is passed through an electronic filter to convert it to an unregulated DC voltage; the filter removes most, but not all of the AC voltage variations. The electric load's tolerance of ripple dictates the minimum amount of filtering that must be provided by a power supply. In some applications, high ripple is tolerated and therefore no filtering is required. For example, in some battery charging applications it is possible to implement a mains-powered DC power supply with nothing more than a transformer and a single rectifier diode, with a resistor in series with the output to limit charging current.
In a switched-mode power supply, the AC mains input is directly rectified and filtered to obtain a DC voltage. The resulting DC voltage is switched on and off at a high frequency by electronic switching circuitry, thus producing an AC current that will pass through a high-frequency transformer or inductor. Switching occurs at a high frequency, thereby enabling the use of transformers and filter capacitors that are much smaller and less expensive than those found in linear power supplies operating at mains frequency. After the inductor or transformer secondary, the high frequency AC is rectified and filtered to pr
Parallel ATA AT Attachment, is an interface standard for the connection of storage devices such as hard disk drives, floppy disk drives, optical disc drives in computers. The standard is maintained by the X3/INCITS committee, it uses the underlying AT AT Attachment Packet Interface standards. The Parallel ATA standard is the result of a long history of incremental technical development, which began with the original AT Attachment interface, developed for use in early PC AT equipment; the ATA interface itself evolved in several stages from Western Digital's original Integrated Drive Electronics interface. As a result, many near-synonyms for ATA/ATAPI and its previous incarnations are still in common informal use, in particular Extended IDE and Ultra ATA. After the introduction of Serial ATA in 2003, the original ATA was renamed to Parallel ATA, or PATA for short. Parallel ATA cables have a maximum allowable length of 18 in; because of this limit, the technology appears as an internal computer storage interface.
For many years, ATA provided the least expensive interface for this application. It has been replaced by SATA in newer systems; the standard was conceived as the "AT Bus Attachment," called "AT Attachment" and abbreviated "ATA" because its primary feature was a direct connection to the 16-bit ISA bus introduced with the IBM PC/AT. The original ATA specifications published by the standards committees use the name "AT Attachment"; the "AT" in the IBM PC/AT referred to "Advanced Technology" so ATA has been referred to as "Advanced Technology Attachment". When a newer Serial ATA was introduced in 2003, the original ATA was renamed to Parallel ATA, or PATA for short; the first version of what is now called the ATA/ATAPI interface was developed by Western Digital under the name Integrated Drive Electronics. Together with Control Data Corporation and Compaq Computer, they developed the connector, the signaling protocols and so on, with the goal of remaining software compatible with the existing ST-506 hard drive interface.
The first such drives appeared in Compaq PCs in 1986. The term Integrated Drive Electronics refers not just to the connector and interface definition, but to the fact that the drive controller is integrated into the drive, as opposed to a separate controller on or connected to the motherboard; the interface cards used to connect a parallel ATA drive to, for example, a PCI slot are not drive controllers: they are bridges between the host bus and the ATA interface. Since the original ATA interface is just a 16-bit ISA bus in disguise, the bridge was simple in case of an ATA connector being located on an ISA interface card; the integrated controller presented the drive to the host computer as an array of 512-byte blocks with a simple command interface. This relieved the mainboard and interface cards in the host computer of the chores of stepping the disk head arm, moving the head arm in and out, so on, as had to be done with earlier ST-506 and ESDI hard drives. All of these low-level details of the mechanical operation of the drive were now handled by the controller on the drive itself.
This eliminated the need to design a single controller that could handle many different types of drives, since the controller could be unique for the drive. The host need only to ask for a particular sector, or block, to be read or written, either accept the data from the drive or send the data to it; the interface used by these drives was standardized in 1994 as ANSI standard X3.221-1994, AT Attachment Interface for Disk Drives. After versions of the standard were developed, this became known as "ATA-1". A short-lived, seldom-used implementation of ATA was created for the IBM XT and similar machines that used the 8-bit version of the ISA bus, it has been referred to as "XT-IDE", "XTA" or "XT Attachment". When PC motherboard makers started to include onboard ATA interfaces in place of the earlier ISA plug-in cards, there was only one ATA connector on the board, which could support up to two hard drives. At the time, in combination with the floppy drive, this was sufficient for most users; when the CD-ROM was developed, many computers would have been unable to accept these drives if they had been ATA devices, due to having two hard drives installed.
Adding the CD-ROM drive would have required removal of one of the drives. SCSI was available as a CD-ROM expansion option at the time, but devices with SCSI were more expensive than ATA devices due to the need for a smart interface, capable of bus arbitration. SCSI added US$100–300 to the cost of a storage device, in addition to the cost of a SCSI host adapter; the less expensive solution was the addition of a dedicated CD-ROM interface, included as an expansion option on a sound card. PC motherboards did not come with support for more than simple beeps from internal speakers. Sound cards included a game port joystick/gamepad port along with interfaces to control a CD-ROM and transmit CD audio to the system; the second drive interface was not well defined. It was first introduced with interfaces specific to certain CD-ROM drives such as Mitsumi, Sony or Panasonic drives, it was common to find early sound cards with two or three separate connectors each designed to match a certain brand of CD-ROM drive.
This evolved into the standard ATA interface for ease of cross-compatibility, though the sound card ATA interface still usual
Nylon is a generic designation for a family of synthetic polymers, based on aliphatic or semi-aromatic polyamides. Nylon is a thermoplastic silky material that can be melt-processed into films, or shapes, it is made of repeating units linked by amide links similar to the peptide bonds in proteins. Nylon polymers can be mixed with a wide variety of additives to achieve many different property variations. Nylon polymers have found significant commercial applications in fabric and fibers, in shapes, in films. Nylon was the first commercially successful synthetic thermoplastic polymer. DuPont began its research project in 1927; the first example of nylon was produced using diamines on February 28, 1935, by Wallace Hume Carothers at DuPont's research facility at the DuPont Experimental Station. In response to Carothers' work, Paul Schlack at IG Farben developed nylon 6, a different molecule based on caprolactam, on January 29, 1938. Nylon was first used commercially in a nylon-bristled toothbrush in 1938, followed more famously in women's stockings or "nylons" which were shown at the 1939 New York World's Fair and first sold commercially in 1940.
During World War II all nylon production was diverted to the military for use in parachutes and parachute cord. Wartime uses of nylon and other plastics increased the market for the new materials. DuPont, founded by Éleuthère Irénée du Pont, first produced gunpowder and cellulose-based paints. Following WWI, DuPont produced other chemicals. DuPont began experimenting with the development of cellulose based fibers producing the synthetic fiber rayon. DuPont's experience with rayon was an important precursor to its marketing of nylon. DuPont's invention of nylon spanned an eleven-year period, ranging from the initial research program in polymers in 1927 to its announcement in 1938, shortly before the opening of the 1939 New York World's Fair; the project grew from a new organizational structure at DuPont, suggested by Charles Stine in 1927, in which the chemical department would be composed of several small research teams that would focus on “pioneering research” in chemistry and would “lead to practical applications”.
Harvard instructor Wallace Hume Carothers was hired to direct the polymer research group. He was allowed to focus on pure research, building on and testing the theories of German chemist Hermann Staudinger, he was successful, as research he undertook improved the knowledge of polymers and contributed to science. In the spring of 1930, Carothers and his team had synthesized two new polymers. One was neoprene, a synthetic rubber used during World War II; the other was a white elastic but strong paste that would become nylon. After these discoveries Carothers’ team was made to shift its research from a more pure research approach investigating general polymerization to a more practically-focused goal of finding “one chemical combination that would lend itself to industrial applications”, it wasn't until the beginning of 1935 that a polymer called "polymer 6-6" was produced. The first example of nylon was produced by Wallace Carothers on February 28, 1935, at DuPont's research facility at the DuPont Experimental Station.
It had all the desired properties of strength. However, it required a complex manufacturing process that would become the basis of industrial production in the future. DuPont obtained a patent for the polymer in September 1938, achieved a monopoly of the fiber. Carothers died 16 months before the announcement of nylon, therefore he was never able to see his success; the production of nylon required interdepartmental collaboration between three departments at DuPont: the Department of Chemical Research, the Ammonia Department, the Department of Rayon. Some of the key ingredients of nylon had to be produced using high pressure chemistry, the main area of expertise of the Ammonia Department. Nylon was considered a “godsend to the Ammonia Department”, in financial difficulties; the reactants of nylon soon constituted half of the Ammonia department's sales and helped them come out of the period of the Great Depression by creating jobs and revenue at DuPont. DuPont's nylon project demonstrated the importance of chemical engineering in industry, helped create jobs, furthered the advancement of chemical engineering techniques.
In fact, it developed a chemical plant that provided 1800 jobs and used the latest technologies of the time, which are still used as a model for chemical plants today. The ability to acquire a large number of chemists and engineers was a huge contribution to the success of DuPont's nylon project; the first nylon plant was located at Seaford, beginning commercial production on December 15, 1939. On October 26, 1995, the Seaford plant was designated a National Historic Chemical Landmark by the American Chemical Society. An important part of nylon's popularity stems from DuPont's marketing strategy. DuPont promoted the fiber to increase demand. Nylon's commercial announcement occurred on October 27, 1938, at the final session of the Herald Tribune's yearly "Forum on Current Problems", on the site of the approaching New York City world's fair; the “first man-made organic textile fiber”, derived from “coal and air” and promised to be “as strong as steel, as fine as the spider’s web” was received enthusiastically by the audience, many of them middle-class women, made the headlines of most newspapers.
Nylon was introduced as part of "The world of tomorrow" at the 1939 New York World's Fa
Berg connector is a brand of electrical connector used in computer hardware. Berg connectors are manufactured by Berg Electronics Corporation of St. Louis, Missouri, a division of Framatome Connectors International. Berg connectors have a 2.54 mm pitch, pins are 0.64 mm square, come as single or double row connectors. Many types of Berg connectors exist; some of the more familiar ones used in IBM PC compatibles are: the four-pin polarized Berg connectors used to connect 3 1⁄2-inch floppy disk drive units to the power supply unit referred to as a "floppy power connector", but also referred to as LP4. This connector has a 2.50 mm pitch. The two-pin Berg connectors used to connect the front panel lights, turbo switch, reset button to the motherboard; the two-pin Berg connectors used as jumpers for motherboard configuration. The power connector on the 3 1⁄2-inch floppy drive, informally known as "the Berg connector", is 2.50 mm pitch. The power cable from the ATX power supply consists of 20 AWG wire to a 4-pin female connector.
The plastic connector housing is TE Connectivity / AMP 171822-4 with female metal contact pins are choice of TE Connectivity / AMP 170204-* or 170262-*, where * is 1 or 2 or 4. The male PCB connector on the 3 1⁄2-inch floppy drive is a polarized right-angle male header, a TE Connectivity / AMP 171826-4, the vertical model is AMP 171825-4. Electrical connector DC connector Insulation-displacement connector JST connector Molex connector Pin header connector FCI, the current owner of Berg
Single Connector Attachment
Single Connector Attachment, or SCA, is a type of connection for the internal cabling of Parallel SCSI systems. There are two versions of this connector: the SCA-1, deprecated, SCA-2, the most recent standard. In addition there are Single-Ended and Low Voltage Differential types of the SCA. SCA is no longer in widespread use, having been superseded by Serial attached SCSI. Since hard disk drives are among the components of a server computer that are the most to fail, there has always been demand for the ability to replace a faulty drive without having to shut down the whole system; this technique is called hot-swapping and is one of the main motivations behind the development of SCA. In connection with RAID, for example, this allows for seamless replacement of failed drives. Hard disk drives make use of two cables: one for data and one for power, they have their specific parameters to be set using jumpers on each drive. Drives employing SCA have only one plug which carries both data and power and allows them to receive their configuration parameters from the SCSI backplane.
The SCA connector for parallel SCSI drives has 80 pins, as opposed to the 68 pin interface found on most modern parallel SCSI drives. Some of the pins in SCA connectors are longer than others, so they are connected first and disconnected last; this ensures the electrical integrity of the whole system. Otherwise, the angle at which the plug is inserted into the drive could be the reason for damage because, for instance, the pin carrying the voltage could get connected before its corresponding ground reference pin; the additional length provides what is known as a pre-charge which provides a means whereby the device is alerted to a pending power surge. That thereby makes the device more stable. To make better use of their hot-plugging capability, SCA drives are installed into drive bays into which they slide with ease. At the far end of these bays is the backplane of the SCSI subsystem located with a connector that plugs into the drive automatically when it is inserted. Full hot-swappable functionality still requires the support of other software and hardware components of the system.
In particular the operating system and RAID layers will need hot-swap support to enable hard drive hot-swapping to be carried out without shutting down the system. SCSI connector, for a description of other SCSI connectors Fibre Channel electrical interface, for details of the SCA-40 connector SAF-TE - active backplanes for sensoring and swap assistance SCSI devices and connectors are specified in SPI-2, SPI-4 and SPI-5 as part of the SCSI-3 Standards Architecture: http://www.t10.org/scsi-3.htm Organization responsible for drafts of the specification documents is the Technical Committee T10: http://www.t10.org/
A video card is an expansion card which generates a feed of output images to a display device. These are advertised as discrete or dedicated graphics cards, emphasizing the distinction between these and integrated graphics. At the core of both is the graphics processing unit, the main part that does the actual computations, but should not be confused as the video card as a whole, although "GPU" is used to refer to video cards. Most video cards are not limited to simple display output, their integrated graphics processor can perform additional processing, removing this task from the central processor of the computer. For example, Nvidia and AMD produced cards render the graphics pipeline OpenGL and DirectX on the hardware level. In the 2010s, there has been a tendency to use the computing capabilities of the graphics processor to solve non-graphic tasks; the graphics card is made in the form of a printed circuit board and inserted into an expansion slot, universal or specialized. Some have been made using dedicated enclosures, which are connected to the computer via a docking station or a cable.
Standards such as MDA, CGA, HGC, Tandy, PGC, EGA, VGA, MCGA, 8514 or XGA were introduced from 1982 to 1990 and supported by a variety of hardware manufacturers. 3dfx Interactive was one of the first companies to develop a GPU with 3D acceleration and the first to develop a graphical chipset dedicated to 3D, but without 2D support. Now the majority of modern video cards are built with either AMD-sourced or Nvidia-sourced graphics chips; until 2000, 3dfx Interactive was an important, groundbreaking, manufacturer. Most video cards offer various functions such as accelerated rendering of 3D scenes and 2D graphics, MPEG-2/MPEG-4 decoding, TV output, or the ability to connect multiple monitors. Video cards have sound card capabilities to output sound – along with the video for connected TVs or monitors with integrated speakers. Within the industry, video cards are sometimes called graphics add-in-boards, abbreviated as AIBs, with the word "graphics" omitted; as an alternative to the use of a video card, video hardware can be integrated into the motherboard, CPU, or a system-on-chip.
Both approaches can be called integrated graphics. Motherboard-based implementations are sometimes called "on-board video". All desktop computer motherboards with integrated graphics allow the disabling of the integrated graphics chip in BIOS, have a PCI, or PCI Express slot for adding a higher-performance graphics card in place of the integrated graphics; the ability to disable the integrated graphics sometimes allows the continued use of a motherboard on which the on-board video has failed. Sometimes both the integrated graphics and a dedicated graphics card can be used to feed separate displays; the main advantages of integrated graphics include cost, compactness and low energy consumption. The performance disadvantage of integrated graphics arises because the graphics processor shares system resources with the CPU. A dedicated graphics card has its own random access memory, its own cooling system, dedicated power regulators, with all components designed for processing video images. Upgrading to a dedicated graphics card offloads work from the CPU and system RAM, so not only will graphics processing be faster, but the computer's overall performance may improve.
Both AMD and Intel have introduced CPUs and motherboard chipsets which support the integration of a GPU into the same die as the CPU. AMD markets CPUs with integrated graphics under the trademark Accelerated Processing Unit, while Intel markets similar technology under the "Intel HD Graphics and Iris" brands. With the 8th Generation Processors, Intel announced the Intel UHD series of Integrated Graphics for better support of 4K Displays. Although they are still not equivalent to the performance of discrete solutions, Intel's HD Graphics platform provides performance approaching discrete mid-range graphics, AMD APU technology has been adopted by both the PlayStation 4 and Xbox One video game consoles; as the processing power of video cards has increased, so has their demand for electrical power. Current high-performance video cards tend to consume a great deal of power. For example, the thermal design power for the GeForce GTX TITAN is 250 watts; when tested while gaming, the GeForce GTX 1080 Ti Founder's Edition averaged 227 watts of power consumption.
While CPU and power supply makers have moved toward higher efficiency, power demands of GPUs have continued to rise, so video cards may have the largest power consumption in a computer. Although power supplies are increasing their power too, the bottleneck is due to the PCI-Express connection, limited to supplying 75 watts. Modern video cards with a power consumption of over 75 watts include a combination of six-pin or eight-pin sockets that connect directly to the power supply. Providing adequate cooling becomes a challenge in such computers. Computers with multiple video cards may need power supplies in the 1000–1500 W range. Heat extraction becomes a major design consideration for computers with two or more high-end video cards. Video cards for desktop computers come in one of two size profiles, which can allow a graphics card to be added to small-sized PCs; some video cards are not of usual size, are thus categorized as being low profile. Video card profiles are based on height only, with low-profile cards taking up less than the height of a
An electrical connector is an electro-mechanical device used to join electrical terminations and create an electrical circuit. Electrical connectors consist of 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. Hundreds of types of electrical connectors are manufactured for power and control applications. Connectors may join two lengths of flexible copper wire or cable, or connect a wire or cable to an electrical terminal. In computing, an electrical connector can be known as a physical interface. Cable glands, known as cable connectors in the US, connect wires to devices mechanically rather than electrically and are distinct from quick-disconnects performing the latter. Electrical connectors are characterised by their pinout and physical construction, contact resistance, insulation between pins and resistance to vibration, resistance to entry of water or other contaminants, resistance to pressure, reliability and ease of connecting and disconnecting.
They may be keyed to prevent insertion in the wrong orientation, connecting the wrong pins to each other, have locking mechanisms to ensure that they are inserted and cannot work loose or fall out. Some connectors are designed such that certain pins make contact before others when inserted, break first on disconnection, it is desirable for a connector to be easy to identify visually, rapid to assemble, require only simple tooling, be inexpensive. In some cases an equipment manufacturer might choose a connector because it is not compatible with those from other sources, allowing control of what may be connected. No single connector has all the ideal properties. Fretting is a common failure mode in electrical connectors that have not been designed to prevent it. Many connectors are keyed, with some mechanical component which prevents mating except with a oriented matching connector; this can be used to prevent incorrect or damaging interconnections, either preventing pins from being damaged by being jammed in at the wrong angle or fitting into imperfectly fitting plugs, or to prevent damaging connections, such as plugging an audio cable into a power outlet.
For instance, XLR connectors have a notch to ensure proper orientation, while Mini-DIN plugs have a plastic projection, which fits into a corresponding hole in the socket and prevent different connectors from being pushed together. 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, toggle or bayonet locking. Depending on application requirements, housings with locking mechanisms may be tested under various environmental simulations that include physical shock and vibration, water spray, etc. to ensure the integrity of the electrical connection and housing seals. 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 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, they are one of the most flexible types of electrical connector available; some disadvantages are that connecting wires is more difficult than plugging in a cable and the terminals are not well protected from contact with persons or foreign conducting materials. 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 spade terminal lugs crimped onto the wires. Printed circuit board mounted terminal blocks allow individual wires to be connected to the circuit board. PCB mounted terminal blocks are soldered to the board, but they are available in a pull-apart version that allows the wire-connecting half of the block to be unplugged from the part, soldered to the PCB.
A general type of connector that screws or clamps bare wire to a post. Many, but not all binding posts will accept a banana connector plug. Crimp-on connectors are a type of solderless connection. 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; these take the form of a fork-shaped opening in the terminal, into which the insulated wire is pressed and which cut through the insulation to contact the conductor within. To make these connections reliably on a production line, special tools are used which control the forces applied during assembly. If properly assembled, the resulting terminations are gas-tight and will last the life of the product. A common example is the multi