Minggu, 06 September 2009

playstation 3

PlayStation 3

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PlayStation 3
PlayStation 3 logo


(Counter-clockwise from top) Original logo, new logo, original model, controller, newer slim model design.
Manufacturer Sony EMCS, Foxconn, ASUSTeK and Logitech for SCEI[1]
Product family PlayStation
Type Video game console
Generation Seventh generation era
Retail availability November 11, 2006
Units sold 24.6 million (as of August 5, 2009)[2] (see below)
Media Blu-ray Disc, DVD, CD (all models)
Super Audio CD (20 GB, 60 GB, 80 GB [CECHExx models]), Digital distribution
Operating system XrossMediaBar
system software version 3.00[3]
CPU 3.2 GHz Cell Broadband Engine with 1 PPE & 7 SPEs
Storage capacity 2.5" SATA hard drive
(20 GB, 40 GB, 60 GB, 80 GB, 120 GB, or 160 GB included) (upgradeable)
Graphics 550 MHz NVIDIA/SCEI RSX 'Reality Synthesizer'
Controller input Sixaxis, DualShock 3
Connectivity
Online services PlayStation Network
Backward
compatibility
PlayStation (all models)
PlayStation 2 (20 GB, 60 GB, and CECHExx 80 GB models)
Predecessor PlayStation 2

The PlayStation 3 (marketed as PLAYSTATION 3[4] until September 2009[5] and officially abbreviated to PS3) is the third home video game console produced by Sony Computer Entertainment, and the successor to the PlayStation 2 as part of the PlayStation series. The PlayStation 3 competes with Microsoft's Xbox 360 and Nintendo's Wii as part of the seventh generation of video game consoles.

A major feature that distinguishes the PlayStation 3 from its predecessors is its unified online gaming service, the PlayStation Network,[6] which contrasts with Sony's former policy of relying on video game developers for online play.[7] Other major features of the console include its robust multimedia capabilities,[8] connectivity with the PlayStation Portable,[9] and its use of a high-definition optical disc format, Blu-ray Disc, as its primary storage medium.[10] The PS3 was also the first Blu-ray 2.0-compliant Blu-ray player on the market.[11]

The PlayStation 3 was first released on November 11, 2006 in Japan,[12] November 17, 2006 in North America and South America,[13] and March 23, 2007 in Europe and Oceania.[14][15] Two SKUs were available at launch: a basic model with a 20 GB hard drive (HDD), and a premium model with a 60 GB hard drive and several additional features[16] (the 20 GB model was not released in Europe or Oceania).[17] Since then, several revisions have been made to the console's available models.[18]

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History

Sony officially unveiled the PlayStation 3 to the public on May 16, 2005, during the E3 2005 conference.[19] A functional version of the system was not present there,[20] nor at the Tokyo Game Show in September 2005,[21] although demonstrations (such as Metal Gear Solid 4: Guns of the Patriots[20]) were held at both events on devkits and comparable PC hardware.[20][21] Video footage based on the predicted PlayStation 3 specifications was also shown (notably a Final Fantasy VII tech demo).[22] The initial prototype shown in May 2005 featured two HDMI ports, three Ethernet ports and six USB ports;[23] however, when the system was shown again a year later at E3 2006, these were reduced to one HDMI port, one ethernet port and four USB ports, presumably to cut costs.[16][24] Two hardware configurations were also announced for the console: a 20 GB model and a 60 GB model, priced at $499 (€499) and $599 (€599), respectively.[16] The 60 GB model would be the only configuration to feature an HDMI port, Wi-Fi internet, flash card readers and a chrome trim with the logo in silver.[16] Both models were announced for a simultaneous worldwide release: November 11 for Japan, and November 17 for North America and Europe.[25]

Silver PlayStation 3 prototype (E3 2005 specs). Note the two additional USB ports, three gigabit ethernet ports and two HDMI ports.

On September 6, 2006, Sony announced that the PAL region (Europe and Oceania) PlayStation 3 launch would be delayed until March 2007, due to a shortage of materials used in the Blu-ray Disc drive.[26]

At the Tokyo Game Show on September 22, 2006, Sony announced that it would include an HDMI port on the 20 GB system, but a chrome trim, flash card readers, silver logo, and Wi-Fi would not be included.[27] Also, the launch price of the Japanese 20 GB model was reduced by over 20%,[28] and the 60 GB model was announced for an open pricing scheme in Japan.[28] During the event, Sony showed 27 playable PS3 games running on final hardware.[29]

Launch

The PlayStation 3 was first released in Japan on November 11, 2006 at 07:00.[12] According to Media Create, 81,639 PS3 systems were sold within 24 hours of its introduction in Japan.[30]

Soon after its release in Japan, the PS3 was released in North America on November 17, 2006.[13] Reports of violence surrounding the release of the PS3 include a customer shot,[31] campers robbed at gunpoint,[32] customers shot in a drive-by shooting with BB guns,[33] and 60 campers fighting over 10 systems.[34]

The console was originally planned for a global release through November, but the European and rest-of-the-world's release was delayed "until March" at the start of September.[35] With it being a somewhat last-minute delay, some companies had taken deposit-based pre-orders, to which Sony informed customers that they were eligible for full refunds or could continue the pre-order.[36] On January 24, 2007, Sony announced that the PlayStation 3 would go on sale on March 23, 2007 in Europe, Australia, the Middle East, Africa and New Zealand.[14][15] The system sold about 600,000 units in its first two days.[37] On March 7, 2007, the 60 GB PlayStation 3 launched in Singapore with a price of S$799.[38] The console was launched in South Korea on June 16, 2007 in a single version equipped with an 80 GB hard drive and IPTV.[39]

Models

Original model

The original PlayStation 3.

There are five PlayStation 3 hardware models, which are commonly referred to by the size of their included hard disk drive: "20", "40", "60", "80" and "160" GB. [16][40] The only difference in the appearance of the first five models was the color of the trim. All retail packages include one or two Sixaxis controllers and/or a DualShock 3 controller (beginning June 12, 2008[41][42]), one miniUSB to USB cable (for connecting the controller to the system), one composite video/stereo audio output cable, one ethernet cable (20, 60, and CECHExx 80 GB only) and one power cable.[40][43][44] All models support software emulation of the original PlayStation,[45][46] but support for PlayStation 2 backwards compatibility has continually diminished with later models.[47] Compatibility issues with games for both systems are detailed in a public database hosted by the manufacturer.[48] All models, excluding the 20GB model, include 802.11 b/g Wi-Fi. In addition to all of the features of the 20 GB model, the 60 GB model has internal IEEE 802.11 b/g Wi-Fi, multiple flash card readers (SD/MultiMedia Card, CompactFlash Type I/Type II, Microdrive,[49] Memory Stick/PRO/Duo), and a chrome colored trim.[50] In terms of hardware, the 80 GB model released in South Korea is identical to the 60 GB model released in the PAL regions, except for the difference in hard drive size.[51]

Like the South Korean and European models, the North American 80 GB model also excludes the PlayStation 2 "Emotion Engine" CPU chip.[47] However, it still keeps the "Graphics Synthesizer" GPU.[52] Due to the elimination of the "Emotion Engine", the level of compatibility was reduced.[47] The 40 GB, 80 GB (2008), and 160 GB models have two USB ports instead of the four USB ports on other models, and do not include multiple flash card readers, SACD support [53], or any backwards compatibility with PlayStation 2 games.[18][47] This was due to the removal of "Graphics Synthesizer" GPU, which stripped the units of all PlayStation 2 based hardware.[54][55]

No official Wi-Fi or flash memory card readers have yet been released by Sony for the 20 GB system, although plans for such add-ons are in place.[56] As of September 2009 Sony have placed no further emphasis on these proposed add-ons.[citation needed] Nevertheless, as the model features four USB 2.0 ports, wireless networking and flash memory card support can already be obtained through the use of widely available external USB adapters.[47]

It was rumored that the Cell processors in the third-generation PS3s (40 GB) would move from a 90 nm process to the newer 65 nm process,[57] which SCEI CEO Kaz Hirai later confirmed,[58] and later to 45 nm. This change lowers the power consumption of the console and makes it less expensive to produce.[59]

Slim model

The redesigned slim PlayStation 3.

Following speculation that a 'slim' model was in the pipeline Sony officially announced the PS3 CECH-2000 on August 18, 2009 at the Sony Gamescom press conference.[60][61] The PS3 slim (officially called the PS3 CECH-2000) features an upgradeable 120GB hard drive and is 33% smaller, 36% lighter, and consumes 34% less power than previous models.[60][62][63] The cooling system has been redesigned and Cell processor has moved to a 45nm manufacturing process.[64]

The PS3 slim also includes support for BRAVIA Sync allowing control of the console over HDMI and runs quieter than previous models but no longer has the ability to install third party operating systems such as Linux.[60][62] The PS3 slim is priced at $299 United States/€299 European Union/£249 United Kingdom/AU$499 Australia/NZ$629 New Zealand/MXN$3,999 Mexico/ P 10,000 Russia/¥29980 Japan and was officially released on September 1, 2009 in North America and Europe and on September 3, 2009 in Japan, Australia and New Zealand.[65][60][62][66] However, some retailers such as Amazon.com, Best Buy, and GameStop started to sell the PS3 slim on August 25, 2009.[67][68] FCC filings also reveal a second slim model, the 250GB CECH-2000B.[69]

Senin, 31 Agustus 2009

fungsi hard disk


Apa Sich Fungsi Hard Disk??


Ketika Anda menyimpan data pada komputer, pasti salah satu media penyimpanan yang paling populer adalah di hardisk. Hardisk sendiri juga memiliki singkatan yaitu HDD. Hardisk disini mempunyai peranan yang cukup penting dalam komputer. Karena merupakan media penyimpanan dari Operating System dari komputer. Seperti Windows maupun Linux. Cobalah Anda bayangkan kalau seandainya tidak ada Hardisk??? Pasti komputer Anda tidak dapat bekerja bukan...
Fungsi utamanya sebagai media penyimpanan atau storage data secara permanen.
Hard disk menyimpan bermacam-macam informasi, salah satunya informasi mengenai hardware yang ada di dalam PC tersebut, lalu OS itu sendiri. Hard disk merupakan salah satu komponen yang menentukan kinerja PC. Semakin cepat hard disk bekerja, semakin cepat pula transfer yang dihasilkan. Hard disk IDE mempunyai 4 tingkatan kelas, masing-masing Ultra DMA/33, Ultra DMA/66, Ultra/100, dan Ultra DMA/133. DMA singkatan dari Direct Memory Access yang berfungsi untuk meningkatkan transfer data. Maksud Ultra DMA/33 adalah daya transfer rata-ratanya 33 MBps. Jadi,Ultra DMA/133 sama dengan transfer datanya 133 MBps. IDE yang terbaru menggunakan SATA {serial ATA} yang sebelumnya menggunakan paralel ATA. Penggunaan hard disk jenis SATA masih sedikit dan mahal, tetapi kecepatan transfernya lebih cepat daripada paralel ATA.
Hard disk lambat laun mengalami peningkatan dalam hal kapasitas penyimpanan data. Pada masa Windows 3.1, penggunaan hard disk dengan ukuran 300 MB sudah cukup. Pada Windows 98,hard disk dengan ukuran 8.3 GB sudah lebih dari cukup. Untuk pemakaian hard disk yang intensif, ukuran tersebut sangat kurang, apalagi menggunakan OS yang baru dan program yang baru pula. Mungkin untuk ukuran standar, hard disk yang dipakai sekarang adalah 20 GB atau lebih tergantung kebutuhan anda.
Kecepatan putar hard disk bermacam-macam, antara lain 5400 RPM, 7200 RPM, atau lebih. Putaran yang dihasilkan hard disk yang memiliki RPM 7200 lebih bising daripada 5400 RPM, akibatnya hard disk menjadi lebih cepat panas. Anda memerlukan kipas pendingin untuk mendinginkan dan menjaga peranti ini dapat hidup bertahan lama.
Demikianlah penjelasan dari saya tentang Hardisk. Semoga menjadi sesuatu yang dapat bermanfaat untuk Anda. Terima kasih.

Fungsi Processor

Penjelasan Tentang Processor

Nah, melanjutkan pembahasan sebelumnya, sekarang akan kita bahas mengenai komponen komputer yang penting banget yaitu PROCESSOR. Tak terasa sudah masuk bagian ke-5 pembahasan mengenai komponen komputer. Penjelasan kali ini mungkin akan sedikit panjang, dan akan disambung pada penjelasan berikutnya, karena membahas processor sama saja dengan membaca buku setebal 500 halaman. Namun saya akan menjelaskan secara simpel dan mudah dimengerti bagi orang awam, tentunya tidak terlalu mendetail penjelasan tentang processor ini.

Processor atau yang lebih dikenal dengan sebutan CPU (Central Processing Unit), merupakan bagian dari komputer yang berfungsi sebagai pusat untuk memproses segala sesuatu yang akan dilakukan oleh komputer. Boleh dikatakan bahwa processor merupakan otak dari sebuah komputer. Bayangkan saja jika manusia tidak memiliki otak, maka tentunya manusia tersebut tidak dapat berbuat apa-apa, dan bisa dikatakan sebagai mayat hidup (kaya zombie donk). Apapun aktivitas yang dilakukan oleh komputer, yang memprosesnya adalah processor.

Silahkan lihat gambar processor dibawah ini !

Merunut sejarah, processor telah banyak mengalami revolusi/perubahan, baik dari segi bentuk/arsitektur, fungsi dan juga kecepatan. Dari jaman processor keluaran Intel yaitu processor Intel 4004 (Generasi awal tapi bukan yang pertama) hingga saat ini yaitu Intel Core 2 Processor. Perbedaannya tentu sangat-sangat jauh baik dari segi bentuk, fungsi dan kecepatan. Intel 4004 memiliki clock speed sebesar 108KHz, jumlah transistor 2300, belum terdapat cache, bus speed 108 KHz, dan berfungsi untuk manipulasi aritmatika dasar. Processor Intel Core 2 Processor memiliki clock speed sebesar 3,2 GHz, jumlah transistor sebanyak 820 juta, cache sebesar 12 MB, bus speed 1600 MHz, dan memiliki fungsi yang sangat kompleks untuk multimedia, komputasi dan sebagainya (fungsi komputer saat ini).

Lihat gambar dibawah ini !

Intel 4004

Intel Core 2 Processor

Fungsi sebuah processor dalam komputer sangatlah penting, karena processor merupakan pusat untuk mengontrol dan memproses kerja sebuah komputer. Sebagai contoh fungsi dari processor adalah ketika Anda hendak menjalankan sebuah aplikasi seperti memutar lagu pada sebuah player seperti Winamp. Pertama-tama tentunya Anda akan mengklik icon Winamp untuk memainkan lagu yang Anda inginkan. Ketika Anda klik Winamp, mouse memberikan sinyal kepada komputer Anda melalui kabel mouse menuju mainboard Anda. Kemudian mainboard melalui jalur khusus, sinyal tersebut diteruskan melalui sebuah jalur BUS yang akan menuju ke Memori Utama, setelah diregister di memori utama, baru kemudian diteruskan menuju Processor untuk diolah sinyal yang dikirimkan tersebut. Setelah processor memproses sinyal tersebut (pengecekan request sinyal tersebut dapat dipenuhi atau tidak), processor akan mengirimkan sinyal kembali kepada komponen-komponen lainnya yang diperlukan untuk menjalankan program Winamp tersebut (seperti harddisk, memory dan sebagainya). Barulah program Winamp akan tampil di monitor Anda.

Perlu Anda ketahui, processor hanya dapat mengenali instruksi dengan notasi bilangan Biner (ex.01010001010). Merupakan notasi untuk perangkat elektronik dimana bilangan NOL (0) menandakan tidak terdapat sinyal listrik, dan bilangan SATU (1) menandakan adanya sinyal listrik. Tentunya urutan proses tersebut tidak dapat dibayangkan hanya sekejap mata saja, karena kecepatan processor yang dapat mencapai 3,2 GHz (3200 Juta getaran perdetik), jadi prosesnya sangat cepat hanya sepersekian mili detik saja.

Pada awalnya, processor hanya difungsikan untuk pengolahan aritmatika saja, seperti halnya kalkulator pada saat ini. Namun sekarang ini processor telah bergeser fungsinya mengarah ke multimedia.

Sabtu, 29 Agustus 2009

tentang kado

hp nokia brand, I had bought for my parents because I won the championship in race two tahfizul. hp nokia that was bought in Jakarta when I was grade 4 to. was bought at a price ranging from nine hundred thousand dollars, although hpnya inexpensive and practical because there is no internet I remain grateful for the use of money by purchasing the hard work my parents, three April two thousand seven date is the first hp that I have from the time the age of eight years, not forgetting my parents who bought the beautiful colors of the color blue like the beautiful sea, after I bought it immediately told to my sister that I have a brand new hp nokia, my sister immediately wanted to borrow it for my sister most like the game I was happily allowed him to play and put on some music hp in hp it, because my brother memakainy too long that I had the battery out immediately took it and immediately hp hp mengecas it, I think the mob was quickly up the batteries I went straight hp menyetopkannya apparently was still not filled my battery went straight back mengecas my hp nokia, for nokia hp is not damaged I still use for my purposes is to call my family or my friends call me and hp it was also able to sms

Senin, 10 Agustus 2009

Processor

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A word processor (more formally known as document preparation system) is a computer application used for the production (including composition, editing, formatting, and possibly printing) of any sort of printable material.

Word processor may also refer to an obsolete type of stand-alone office machine, popular in the 1970s and 80s, combining the keyboard text-entry and printing functions of an electric typewriter with a dedicated computer for the editing of text. Although features and design varied between manufacturers and models, with new features added as technology advanced, word processors for several years usually featured a monochrome display and the ability to save documents on memory cards or diskettes. Later models introduced innovations such as spell-checking programs, increased formatting options, and dot-matrix printing. As the more versatile combination of a personal computer and separate printer became commonplace, the word processor disappeared.

Word processors are descended from early text formatting tools (sometimes called text justification tools, from their only real capability). Word processing was one of the earliest applications for the personal computer in office productivity.

Although early word processors used tag-based markup for document formatting, most modern word processors take advantage of a graphical user interface providing some form of What You See Is What You Get editing. Most are powerful systems consisting of one or more programs that can produce any arbitrary combination of images, graphics and text, the latter handled with type-setting capability.

Microsoft Word is the most widely used computer word processing system; Microsoft estimates over five hundred million people use the Office suite, which includes Word. There are also many other commercial word processing applications, such as WordPerfect, which dominated the market from the mid-1980s to early-1990s, particularly for machines running Microsoft's MS-DOS operating system. Open-source applications such as Abiword, KWord, LyX and OpenOffice.org Writer are rapidly gaining in popularity.[citation needed] Online word processors such as Google Docs are a relatively new category.

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[edit] Characteristics

Word processing typically refers to text manipulation functions such as automatic generation of:

  • batch mailings using a form letter template and an address database (also called mail merging);
  • indices of keywords and their page numbers;
  • tables of contents with section titles and their page numbers;
  • tables of figures with caption titles and their page numbers;
  • cross-referencing with section or page numbers;
  • footnote numbering;
  • new versions of a document using variables (e.g. model numbers, product names, etc.)

Other word processing functions include "spell checking" (actually checks against wordlists), "grammar checking" (checks for what seem to be simple grammar errors), and a "thesaurus" function (finds words with similar or opposite meanings). In most languages grammar is very complex, so grammar checkers tend to be unreliable and also require a large amount of RAM.[citations needed] Other common features include collaborative editing, comments and annotations, support for images and diagrams and internal cross-referencing.

Word processors can be distinguished from several other, related forms of software:

Text editors (modern examples of which include Notepad, BBEdit, Kate, Gedit), were the precursors of word processors. While offering facilities for composing and editing text, they do not format documents. This can be done by batch document processing systems, starting with TJ-2 and RUNOFF and still available in such systems as LaTeX (as well as programs that implement the paged-media extensions to HTML and CSS). Text editors are now used mainly by programmers, website designers, and computer system administrators. They are also useful when fast startup times, small file sizes, editing speed and simplicity of operation are preferred over formatting.

Later desktop publishing programs were specifically designed to allow elaborate layout for publication, but often offered only limited support for editing. Typically, desktop publishing programs allowed users to import text that was written using a text editor or word processor.

Almost all word processors enable users to employ styles, which are used to automate consistent formatting of text body, titles, subtitles, highlighted text, and so on.

Styles greatly simplify managing the formatting of large documents, since changing a style automatically changes all text that the style has been applied to. Even in shorter documents styles can save a lot of time while formatting. However, most help files refer to styles as an 'advanced feature' of the word processor, which often discourages users from using styles regularly.

[edit] Document statistics

A

Power supply

Power supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others.

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[edit] Electrical power supplies

This term covers the power distribution system together with any other primary or secondary sources of energy such as:

Constraints that commonly affect power supplies are the amount of power they can supply, how long they can supply it without needing some kind of refueling or recharging, how stable their output voltage or current is under varying load conditions, and whether they provide continuous power or pulses.

The regulation of power supplies is done by incorporating circuitry to tightly control the output voltage and/or current of the power supply to a specific value. The specific value is closely maintained despite variations in the load presented to the power supply's output, or any reasonable voltage variation at the power supply's input. This kind of regulation is commonly categorized as a Stabilized power supply.

[edit] Power supply types

Power supplies for electronic devices can be broadly divided into linear and switching power supplies. The linear supply is a relatively simple design that becomes increasingly bulky and heavy for high current devices; voltage regulation in a linear supply can result in low efficiency. A switched-mode supply of the same rating as a linear supply will be smaller, is usually more efficient, but will be more complex.

[edit] Battery power supply [1]

A battery is a type of linear power supply that offers benefits that traditional line-operated power supplies lack: mobility, portability, and reliability. A battery consists of multiple electrochemical cells connected to provide the voltage desired.

The most commonly used dry-cell battery is the carbon-zinc dry cell battery.[2] Dry-cell batteries are made by stacking a carbon plate, a layer of electrolyte paste, and a zinc plate alternately until the desired total voltage is achieved. The most common dry-cell batteries have one of the following voltages: 1.5, 3, 6, 9, 22.5, 45, and 90. During the discharge of a carbon-zinc battery, the zinc metal is converted to a zinc salt in the electrolyte, and magnesium dioxide is reduced at the carbon electrode. These actions establish a voltage of approximately 1.5 V.

The lead-acid storage battery may be used. This battery is rechargeable; it consists of lead and lead/dioxide electrodes which are immersed in sulfuric acid. When fully charged, this type of battery has a 2.06-2.14 V potential. During discharge, the lead is converted to lead sulfate and the sulfuric acid is converted to water. When the battery is charging, the lead sulfate is converted back to lead and lead dioxide.

A nickel-cadmium battery has become more popular in recent years. [3]This battery cell is completely sealed and rechargeable. The electrolyte is not involved in the electrode reaction, making the voltage constant over the span of the batteries long service life. During the charging process, nickel oxide is oxidized to its higher oxidation state and cadmium oxide is reduced. The nickel-cadmium batteries have many benefits. They can be stored both charged and uncharged. They have a long service life, high current availabilities, constant voltage, and the ability to be recharged.

[edit] Linear power supply

A home-made linear power supply (used here to power amateur radio equipment)

An AC powered linear power supply usually uses a transformer to convert the voltage from the wall outlet (mains) to a different, usually a lower voltage. If it is used to produce DC, a rectifier is used. A capacitor is used to smooth the pulsating current from the rectifier. Some small periodic deviations from smooth direct current will remain, which is known as ripple. These pulsations occur at a frequency related to the AC power frequency (for example, a multiple of 50 or 60 Hz).

The voltage produced by an unregulated power supply will vary depending on the load and on variations in the AC supply voltage. For critical electronics applications a linear regulator will be used to stabilize and adjust the voltage. This regulator will also greatly reduce the ripple and noise in the output direct current. Linear regulators often provide current limiting, protecting the power supply and attached circuit from overcurrent.

Adjustable linear power supplies are common laboratory and service shop test equipment, allowing the output voltage to be set over a wide range. For example, a bench power supply used by circuit designers may be adjustable up to 30 volts and up to 5 amperes output. Some can be driven by an external signal, for example, for applications requiring a pulsed output.

The simplest DC power supply circuit consists of a single diode and resistor in series with the AC supply. This circuit is common in rechargeable flashlights.

[edit] AC/ DC supply

In the past, mains electricity was supplied as DC in some regions, AC in others. A simple, cheap linear power supply would run directly from either AC or DC mains, often without using a transformer. The power supply consisted of a rectifier and a capacitor filter. The rectifier was essentially a conductor, having no sudden effect when operating from DC.

[edit] Switched-mode power supply

A computer's switched mode power supply unit.

A switched-mode power supply (SMPS) works on a different principle. AC mains input is directly rectified without the use of a transformer, to obtain a DC voltage. This voltage is then sliced into small pieces by a high-speed electronic switch. The size of these slices grows larger as power output requirements increase.

The input power slicing occurs at a very high speed (typically 10 kHz — 1 MHz). High frequency and high voltages in this first stage permit much smaller step down transformers than are in a linear power supply. After the transformer secondary, the AC is again rectified to DC. To keep output voltage constant, the power supply needs a sophisticated feedback controller to monitor current draw by the load.

Modern switched-mode power supplies often include additional safety features such as the crowbar circuit to help protect the device and the user from harm.[4] In the event that an abnormal high current power draw is detected, the switched-mode supply can assume this is a direct short and will shut itself down before damage is done. For decades PC computer power supplies have also provided a power good signal to the motherboard which prevents operation when abnormal supply voltages are present.

Switched mode power supplies have an absolute limit on their minimum current output. [5] They are only able to output above a certain power level and cannot function below that point. In a no-load condition the frequency of the power slicing circuit increases to great speed, causing the isolation transformer to act as a tesla coil, causing damage due to the resulting very high voltage power spikes. Switched-mode supplies with protection circuits may briefly turn on but then shut down when no load has been detected. A very small low-power dummy load such as a ceramic power resistor or 10 watt light bulb can be attached to the supply to allow it to run with no primary load attached.

Power factor has become a recent issue of concern for computer manufacturers. Switched mode power supplies have traditionally been a source of power line harmonics and have a very poor power factor. Many computer power supplies built in the last few years now include power factor correction built right into the switched-mode supply, and may advertise the fact that they offer 1.0 power factor.

By slicing up the sinusoidal AC wave into very small discrete pieces, the portion of the alternating current not used stays in the power line as very small spikes of power that cannot be utilized by AC motors and results in waste heating of power line transformers. Hundreds of switched mode power supplies in a building can result in poor power quality for other customers surrounding that building, and high electric bills for the company if they are billed according to their power factor in addition to the actual power used. Filtering capacitor banks may be needed on the building power mains to suppress and absorb these negative power factor effects.

[edit] Programmable power supply

Programmable power supplies are those in which the output voltage can be varied remotely. One possible option is digital control by a computer interface. Variable properties include voltage, current, and frequency. This type of supply is composed of a processor, voltage/current programming circuits, current shunt, and voltage/current read-back circuits.

Programmable power supplies can furnish DC, AC, or both types of output. The AC output can be either single-phase or three-phase. Single-phase is generally used for low-voltage, while three-phase is more common for high-voltage power supplies.

When choosing a programmable power supply, several specifications should be considered. For AC supplies, output voltage, voltage accuracy, output frequency, and output current are important attributes. For DC supplies, output voltage, voltage accuracy, current, and power are important characteristics. Many special features are also available, including computer interface, overcurrent protection, overvoltage protection, short circuit protection, and temperature compensation. Programmable power supplies also come in a variety of forms. Some of those are modular, board-mounted, wall-mounted, floor-mounted or bench top.

Programmable power supplies are now used in many applications. Some examples include automated equipment testing, crystal growth monitoring, and differential thermal analysis [6].

[edit] Uninterruptible power supply

An Uninterruptible Power Supply (UPS) takes its power from two or more sources simultaneously. It is usually powered directly from the AC mains, while simultaneously charging a storage battery. Should there be a dropout or failure of the mains, the battery instantly takes over so that the load never experiences an interruption. Such a scheme can supply power as long as the battery charge suffices, e.g., in a computer installation, giving the operator sufficient time to effect an orderly system shutdown without loss of data. Other UPS schemes may use an internal combustion engine or turbine to continuously supply power to a system in parallel with power coming from the AC mains. The engine-driven generators would normally be idling, but could come to full power in a matter of a few seconds in order to keep vital equipment running without interruption. Such a scheme might be found in hospitals or telephone central offices.

[edit] High-voltage power supply

High voltage refers to an output on the order of hundreds or thousands of volts. High-voltage power supplies use a linear setup to produce an output voltage in this range.

When choosing a high-voltage power supply, there are several options to consider. Some of these are maximum current, maximum power, maximum voltage, output polarity, user interface, and style. The first four of these characteristics of course depend upon the supply's intended application. There are many available types of user interfaces. For example, the interface may be local in the form of a digital meter, or analog meter. Also, the interface can be remote, as in a computer connection. Numerous styles of high-voltage power supplies are also manufactured. Available models come in printed circuit board mount, open frame (as designed to be incorporated into an instrument), and rack mount. Models with multiple outputs can also be found [7].

[edit] Voltage multipliers

Voltage multipliers, as the name implies, are circuits designed to multiply the input voltage. The input voltage may be doubled (voltage doubler), tripled (voltage tripler), quadrupled (voltage quadrupler), etc. Voltage multipliers are also power converters. An AC input is converted to a higher DC output. These circuits allow high voltages to be obtained using a much lower voltage AC source.

Typically, voltage multipliers are composed of half-wave rectifiers, capacitors, and diodes. For example, a voltage tripler consists of three half-wave rectifiers, three capacitors, and three diodes. Full-wave rectifiers may be used in a different configuration to achieve even higher voltages. Also, both parallel and series configurations are available. For parallel multipliers, a higher voltage rating is required at each consecutive multiplication stage, but less capacitance is required. The voltage capability of the capacitor limits the maximum output voltage.

Voltage multipliers have many applications. For example, voltage multipliers can be found in everyday items like televisions and photocopiers. Even more applications can be found in the laboratory, such as cathode ray tubes, oscilloscopes, and photomultiplier tubes.[8][9]

[edit] Power supply applications

[edit] Computer power supply

A modern computer power supply is a switched-mode supply designed to convert 110-240 V AC power from the mains supply, to several output both positive (and historically negative) DC voltages in the range + 12V,-12V,+5V,+5VBs and +3.3V. The first generation of computers power supplies were linear devices, but as cost became a driving factor, and weight became important, switched mode supplies are almost universal.

The diverse collection of output voltages also have widely varying current draw requirements, which are difficult to all be supplied from the same switched-mode source. Consequently most modern computer power supplies actually consist of several different switched mode supplies, each producing just one voltage component and each able to vary its output based on component power requirements, and all are linked together to shut down as a group in the event of a fault condition.

The most common modern computer power supplies are built to conform to the ATX form factor. The power rating of a PC power supply is not officially certified and is self-claimed by each manufacturer.[10]A common way to reach the power figure for PC PSUs is by adding the power available on each rail, which will not give a true power figure. The more reputable makers advertise "True Wattage Rated" to give consumers the idea that they can trust the power advertised.

[edit] Welding power supply