SMPS

A switched-mode power supply (also switching-mode power supply, SMPS, or simply switcher) is an electronic power supply unit (PSU) that incorporates a switching regulator in order to provide the required dc output voltage.
Although the term "power supply" has been in use since radios were first powered from the line/mains, that does not mean that it is a source of power, in the sense that a battery provides power. It is simply a device that (usually) accepts commercial AC power and provides one or more DC outputs. It would be more correctly referred to as a power converter, but long usage has established the term.

Whilst a linear regulator maintains the desired output voltage by dissipating excess power in a pass power transistor, the switched-mode power supply switches a power transistor between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. It switches at a much higher frequency (tens to hundreds of kHz) than that of the AC line (mains). This means that the transformer that it feeds can be much smaller than one connected directly to the line/mains. Switching creates a rectangular waveform that typically goes to the primary of the transformer.

Usually several secondaries feed rectifiers, series inductors, and filter capacitors to provide various DC outputs with low ripple.

THe main advantage of this method is greater efficiency because the switching transistor dissipates little power when it is outside of its active region (i.e., when the transistor acts like a switch and either has a negligible voltage drop across it or a negligible current through it). Other advantages include smaller size and lighter weight (from the elimination of low frequency transformers which have a high weight) and lower heat generation due to higher efficiency. Disadvantages include greater complexity, the generation of high-amplitude, high-frequency energy that the low-pass filter must block to avoid electromagnetic interference (EMI), and a ripple voltage at the switching frequency and the harmonic frequencies thereof.

Very low cost SMPS may couple electrical switching noise back onto the mains power line, causing interference with A/V equipment connected to the same phase. Non power-factor-corrected SMPSs also cause harmonic distortion.

If the SMPS has an AC input, then the first stage is to convert the input to DC. This is called rectification. The rectifier circuit can be configured as a voltage doubler by the addition of a switch operated either manually or automatically. This is a feature of larger supplies to permit operation from nominally 120 volt or 240 volt supplies. The rectifier produces an unregulated DC voltage which is then sent to a large filter capacitor. The current drawn from the mains supply by this rectifier circuit occurs in short pulses around the AC voltage peaks. These pulses have significant high frequency energy which reduces the power factor. Special control techniques can be employed by the following SMPS to force the average input current to follow the sinusoidal shape of the AC input voltage thus the designer should try correcting the power factor. An SMPS with a DC input does not require this stage. An SMPS designed for AC input can often be run from a DC supply (for 230V AC this would be 330V DC), as the DC passes through the rectifier stage unchanged. It's however advisable to consult the manual before trying this, though most supplies are quite capable of such operation even though nothing is mentioned in the documentation. However, this type of use may be harmful to the rectifier stage as it will only utilize half of diodes in the rectifier for the full load. This may result in overheating of these components, and cause them to fail prematurely. [3]

If an input range switch is used, the rectifier stage is usually configured to operate as a voltage doubler when operating on the low voltage (~120 VAC) range and as a straight rectifier when operating on the high voltage (~240 VAC) range. If an input range switch is not used, then a full-wave rectifier is usually used and the downstream inverter stage is simply designed to be flexible enough to accept the wide range of dc voltages that will be produced by the rectifier stage. In higher-power SMPSs, some form of automatic range switching may be used.

The inverter stage converts DC, whether directly from the input or from the rectifier stage described above, to AC by running it through a power oscillator, whose output transformer is very small with few windings at a frequency of tens or hundreds of kilohertz (kHz). The frequency is usually chosen to be above 20 kHz, to make it inaudible to humans. The output voltage is optically coupled to the input and thus very tightly controlled. The switching is implemented as a multistage (to achieve high gain) MOSFET amplifier. MOSFETs are a type of transistor with a low on-resistance and a high current-handling capacity. Since only the last stage has a large duty cycle, previous stages can be implemented by bipolar transistors leading to roughly the same efficiency. The second last stage needs to be of a complementary design, where one transistor charges the last MOSFET and another one discharges the MOSFET. A design using a resistor would run idle most of the time and reduce efficiency. All earlier stages do not weight into efficiency because power decreases by a factor of 10 for every stage (going backwards) and thus the earlier stages are responsible for at most 1% of the efficiency. This section refers to the block marked Chopper in the block diagram.

LCD Monitor v/s CRT Monitor

The demand of LCD (Liquid crystal display) monitors is rapidly growing in the market. With the advancement of technology LCD are quite familiar to computer user and we can see most of them are using LCD. It would be a challenge for LCD manufacturing companies to fulfill the growing demand of LCD in the market.

Some comparison between LCD monitor and CRT monitor is given below

1. LCD panels are only an inch thick without including the stand. These consume less power and don’t radiate a lot of heat when used, unlike CRT monitor.

2. Their digital display is sharper and produce good quality picture as compare to CRT monitor.

3. An LCD monitor is slim and comes in a very compact configuration. They can be fit easily into any less vacant part of the room or any where. They are very suitable for small offices or homes

4. But its difficult for everyone to afford LCD display because LCD display screens or monitors are quite expensive as compare to CRT

5. LCD screens or displays are very sensitive and should be handling with care. They are not suitable for minor used.

6. As far as moving images or 3D images are concern, LCD screen are blurry and unclear. Hence, someone prefers CRT over LCD screens. Graphic designers also prefer the CRT over the LCD. Not only that, the color gradations are not clear in the LCD panel, and it causes problems in differentiating between darker shades, creating practical problems for graphic designers.

Promotional Gifts at the World Cup

Unless you've been hiding under a rock for the last few weeks you won't have failed to notice that 2010 Fifa World Cup is well underway. Watching the TV you can hear the constant cacophony of vuvuzelas and other national tradions such as Swiss cow bells, English Brass Bands and native costume from around the world. You can also see the huge range of emphemera on display including scarves, helmets/hats and whistles, not to mention the vast range of promotional gifts including fan hands, promotional t-shirts amongst other things.

All the fans of the participating nations have really got behind their national teams and the English fans are all preparing for today's big match against Algeria. Let's hope they've made the most of all their promotional products so that they can be the '12th man' and help push Engalnd to victory!

Reusable Bags - Eco-Friendly Reusable Bag Promotional Items

Custom Earth Promos specializes in environmentally friendly promotional items such as the duration of the reusable bags, recycled bags, seeds, paper, and recycled plastic bottles BPA free, stainless steel bottles, lanyards promotional recycled and recyclable USB drive.

We have the ability to produce another promotional item of the finest eco-friendly material. Fortunately for our customers, we have a direct source for all your promotional email messages point is! We believe that providing our customers with factory direct pricing allows us to build business relationships estimated for the coming years. Other benefits not only the price includes our ability to completely customize any product from scratch, which is one of the biggest differentiator between Custom Promotions and our country competitive. I can not dream, we can produce!

We offer a variety of environmentally friendly reusable bag, including but not limited to bags recycled water bottle, non-woven polypropylene bags, bamboo bags and jute bags. Our reusable bags are reusable water bottle made from 85% recycled water bottles! We actually break into recycled plastic bottles and turn them into bags. Our non woven bags are manufactured from the finest materials up to 100 GSM national and thicker by using one of our factories abroad! Non-woven polypropylene is 20% recycled material, and has become the norm in most grocery stores. Our reusable bag is made from real bamboo! They are fully recyclable, and most resembles an excellent soft material. Jute is a natural material that is becoming increasingly popular. All our bags are perfect for trade shows and gifts for any event.

We offer two different styles of green bottles, plastic bottles and BPA free water bottles and stainless steel. With our overseas factories, we are able to provide a color print wrapped around the whole bottle. There are no limitations on the personal impression of the Earth Offers! Stainless steel is the most popular bottle we found that aluminum toxins that are unsafe for people to digest. Our ropes are made of recycled corn, recycled water bottles and bamboo. All our equipment is top quality. Our customers have the opportunity to create a cable from the beginning. Ropes and cables offer sublimated color silk imprint on the screen too. You can add a removable clip on the front or a breakaway safety device in the back!

Inverter Advantage

The award-winning range of Fujitsu General which has Nocria inverter air conditioners has been extended with the addition of three new models, as an increasing number of households invest in heating for the colder months ahead.
“With improved air conditioning MEPS (Minimum Energy Performance Standards) introduced by state governments in April 2006 and revised levels expected in October this year, inverter air conditioners will continue to be viewed as the ideal, energy efficient heating appliance this winter,” says Philip Perham, Fujitsu’s general manager – marketing/sales.
The automatic filter cleaning function of the Nocria ceiling wall inverters, a world first, maintains a smooth air flow by preventing the filters from being clogged with dust and other harmful particles.
A titan apatite filter sterilises dirt and dust and can remove 99.99% of cigarette odours and bacteria. The indoor unit’s fan which is driven by an axial gap motor is 1.5 times more compact than a conventional motor yet produces a higher power output. Rotating efficiency is increased by 10% and the electromagnetic field simulation technology incorporated within the design of the new motor enables low vibration and low noise.
Incorporating a new computer designed fan, the Nocria air conditioners increase the maximum air flow by 10 percent over that of conventional models. Strong vertical air flow provides powerful floor level heating and the healthy horizontal air flow prevents cool air from blowing directly at anyone in the room.
The Nocria inverters have an inner drying function designed to prevent the growth of mould and fungus. After operation ends, by pressing the coil dry button a 30 minute speed cleaning operation commences.

Practice Bedroom Decorating Tips

Teenagers have the most unpredictable minds in the world. They changed their outfit, hairdos and outfit in a matter of minutes. They want their room to look cool and fun and they do not want it to look childlike and outdated.
Decorating you bedroom does not need to be as difficult and stressful as you think it is because it can be fun and exciting. You do not need to hire a professional interior designer to beautify their room, you only need to allocate adequate time, creative ability, knowledge in interior design and decoration. You can also read home interior decorating magazines, surf the Internet for additional information or ask ideas from your friends and colleagues. To gain some insights on bedroom decorating, read the article and follow the tips mentioned below.
Due to their active and wild lifestyles that most teenagers have, you are worried on what to place or how to decorate your teen's bedroom. Majority of them love lots of blings and teenage stuffs in their bedroom that parents do not understand or like.
Teenagers' bedrooms are their refuge and sanctuary, a place where they get away from school obligations, parental and peer pressure, it is best that you let them involve in the task. They cannot only decorate their own room, but they can create and can change the look of their room by arranging the furniture pieces, painting their room, and hanging picture frames and posters.
Creating a perfect retreat for you teenager is not only challenging, but tricky project, thus, you should not take their ideas and suggestions for granted because they know what are the popular fads and trends in the market today.
No matter what design you take, always remember that their bedroom can be successfully decorated if you balance between trendy and classic interior design.
Tips to Consider:

• Budget - Before you start any change on their room, consider first how much money you can spare for the project.
• Color scheme - Even though you want a different color for your teenagers' room, it is best to accede to your child's choice. Some teenagers prefer to neutral shades, while some girls go for shades for pink, while some boys prefer green colors.
• Furniture - Before you purchase any new furniture pieces in their room, conduct an inventory on your teenager's bedroom and decide what items to remove, to repair, to buy and to retain. Ask them what items they want in their room.
• Accessories - There are numerous teenage decorative accessories that can be incorporated in their room. Ask ideas from them. Some of them want the pictures of their idols, like the Jonas brothers or Hannah Montana, while some want their own photographs hang in picture frames.
• Message Center - a chalkboard, a cork tiles or a white board can serve as a message center. It is a vital item where you can leave your message to your child.
• Comfort - place accessories that encourage comfort, like cushioned bench, stuffed chairs, throw pillows or plush fabrics.

Article Source : http://bit.ly/lOM7Jk

How to choose a Power supply (PSU)

In an ideal PC assemble, usually we put forward some of the hardware that we think is most important, like mainboard, processor, memory, VGA. Especially you who like brain-tweaking the computer to get the best PC games or even overclocking. While the Power Supply (PSU) is often ignored.

In fact, without the power supply is good, all powerful tools that we choose will not be able to work with the optimal.There are many types of PSU but not all good for use in a PC that has a high specs. Tips for choosing a fixed PSU specs are very high in need because without the PSU is good all the devices will not work optimally reliable.
Just to give an overview about the PSU.

1. WATTS
PSU using measures watts in power supply. Watt in the PSU is calculated by multiplying voltage by amperage. The higher the wattage PSU so power can be supplied higher.

2. Rails
Conductor size, power is in the form of volt. In klasifikasin be +3.3 V, + 5V, +12 V,-5V and-12V. As a benchmark simply note that (+) only because the rail (-) only for the use of PCs in the past that is for ISA slots, and Floppy drives. Calculating the power of each rail simply by mengalikanya with the ampere. Then add the third rail is to know the maximum capacity of the PSU.

3. Multiple Rails
Along with the development of processor technology and VGA +12 V rail increasingly require high power. This high power requirement will make the +12 V rails into heat and make the performance of the PSU becomes unstable, so to overcome this then divided into 2 rail, 3 rail even the newest four rails. That is to say that using a dual rail PSU will be more stable in the power supply because the heat can be suppressed. The result is wasted energy into heat is reduced.

4. Voltage Regulator
Often also referred to this is the change in output ripple voltage generated by the PSU. Changes in this voltage fruktuatif caused by conditions that do not konstants example from idle and then became a full load. The recommended safe standard is + / - 5% of railnya. The fewer the better the output ripple PSU.

Voltage regulators can be called as an essential component in maintaining the hardware in the computer hardware. For the flutuatif volt up and down in a short time causes the hardware components become damaged. Especially the most frequent subject is the hard drive.

5. Hold Up time
Backup power is available at PSU before running out of power. Under these conditions there is no power failure or power supply how much power is able to supply power PSU accommodated. The bigger its reserves mean more time in dealing with input condition die. PSU is good to have high Hold Up Time, which he uses to signify good component.

6. Over-Voltage Protection
PSU has an almost all these features. Its function is obvious that is to protect from power surges. So if there was a big auto power PSU will decide the current. With this feature the user can avoid the disaster of shorting or hit by lightning. So if there was a big hit that high are not the first PSU other components because the current is already on another cut klo PSU there is no feature of his spikes directly forwarded to all computer components.