How to Search For Computer Repair Tools With the Best Deal Through Internet

Computers have played an important role in our daily life. Most of us use computers everyday in our work place as well as for our studies. Besides, we use computers to surf the internet to obtain the latest news. When our computers break down, it is indeed time-consuming for us to send our computers to the specialists to fix the problems. In fact, we can repair the computers on our own with the right repair tools immediately. We can also keep our computers at good condition with some useful tools.
Nowadays, there are many repair tools available in the market. They are customized to fix the problems arise from both hardware and software. Different tools have different functions. Some software tools enable us to restore software systems while some allow us to analyze the hardware components and troubleshoot the problems when the operating system is not functioning. If you are facing hardware problems, after identifying your needs, you can start searching around to look for necessary tools such as pliers, special screwdrivers, ribbon cables, etc. These tools can assist you to repair and replace hardware components easily. Besides these common tools, there are also some special items available in the market to fix problems related to memory modules, jumpers, hard drives, on-board resistors, and so on. At the same time, you can find some tools which are meant for maintenance.
We don't send our "problematic" computers to the specialists because we need to save cost. Same principle applies to the computer repair tools. We need to put in some effort and time to look for cheap items but with good quality. Although we can obtain all the repair kits from the reputable computer stores, the prices offered might not be the lowest. In order to get the best deal, you are advised to obtain the kits from internet. There are many online shops which offer great discounts to the online shoppers. The only risk you may face is you may get fake products. Some unethical online shops like to trap the buyers by selling low quality products.
In order to reduce your financial risk, you are advised to do your homework before making your purchasing decision. It is a must for you to read the users' review carefully so that you are able to look for reliable suppliers. It will be good if you can get recommendation from someone you know. After knowing the quality of different tools, you should then compare the prices from one online supplier to another. By doing thorough comparison, you will be able to grab the best deal easily. By knowing the products more, you will be able to determine whether it is worthwhile for you to invest on the particular kits or not.
To sum up, searching for the right repair tools is not hard. You just need to apply the right strategy.

How good is this computer?

How good would you say this computer is:-Intel Core 2 Quad Q6600(2,40 GHz, 1066MHz FSB)-2048(2x1024) MB RAM DDR2, 667 MHz(4 sockets DDR2 Max, 8 GB/2 socket DDR3 max 4GB)-329 GB Harddrive, 7.299 rpm, SATA-NVIDIA Geforce 8800GTX 768MB(2x DVI, VGA adapter included, HDTV Output)-DVD/R/RW-10/100 Ethernet card-Creative X-Fi Extreme Soundcard-Motherboard: Gigabyte P35C-DS3R-Vista Home Premiumprice: 2,200 US dollars.I dont want to build my own comp. I know it will be cheaper but I only want to upgrade basic stuff, like GFX card or Ram. I was wondering if this computer would be a good long term investment, or if there is something in it, that is on the edge of being outdated?last time I bought a comp, I got one of the last ones with AGP, instead of the new PCI-Express, so it made it difficult to upgrade it! I was wondering about, how well you think this computer would be able to play crysis, gears of war and such? I mean, it has no SLI, so I was wondering if it would be weak in the graphical performance.

????How good is this computer?
It won't max out Crysis (Like everything on the market) If you are getting 2 8800GTX (Which I highly recommend you don't) I would wait for the 9XXX series to comeout next year, those will be able to max crysis. SLI doesn't double the power, it only gives you about a 30% increase in preformance from 1 card.How good is this computer?
Change that 8800GTX to a 8800GT and you will save a lot of money.The RAM, although might be no difference - should be changed to a DDR2 800 one.No need for an extra ethernet card, all motherboards come with one inbuilt.Unless music/sound is important to you, you can drop the sound card for now, and pick it up later on.
[QUOTE=''Luminouslight'']It won't max out Crysis (Like everything on the market) If you are getting 2 8800GTX (Which I highly recommend you don't) I would wait for the 9XXX series to comeout next year, those will be able to max crysis. SLI doesn't double the power, it only gives you about a 30% increase in preformance from 1 card.[/QUOTE]is crysis really that demanding?if there are games already on the marked which can not be maxed out by this, I kinda wonder what price it would be to have a computer that would be able to max out all games... including does coming 1 or 2 years from now!?!??!?!
I agree with the 8800GT suggestion. An 8800GT will give you nearly the performance of an 8800GTX, only for a much lower price (~ $270). Although if I were in your position, I would just wait a bit longer for the Geforce 9 series cards. None of the cards from this generation seem to fare very well with Crysis and other DX10 games.
[QUOTE=''cmdrmonkey'']I agree with the 8800GT suggestion. An 8800GT will give you nearly the performance of an 8800GTX, only for a much lower price (~ $270). Although if I were in your position, I would just wait a bit longer for the Geforce 9 series cards. None of the cards from this generation seem to fare very well with Crysis and other DX10 games. [/QUOTE]is it due to slobby hardware with the GF 8 series, or is it just plain bad driver support? but that can be fixed right?
[QUOTE=''cmdrmonkey'']I agree with the 8800GT suggestion. An 8800GT will give you nearly the performance of an 8800GTX, only for a much lower price (~ $270). Although if I were in your position, I would just wait a bit longer for the Geforce 9 series cards. None of the cards from this generation seem to fare very well with Crysis and other DX10 games. [/QUOTE]9 series is rumored to come out in Q2 next year, so around 4-5 months from here. I wouldnt wait that long...
[QUOTE=''LuffyTubby''][QUOTE=''cmdrmonkey'']I agree with the 8800GT suggestion. An 8800GT will give you nearly the performance of an 8800GTX, only for a much lower price (~ $270). Although if I were in your position, I would just wait a bit longer for the Geforce 9 series cards. None of the cards from this generation seem to fare very well with Crysis and other DX10 games. [/QUOTE]is it due to slobby hardware with the GF 8 series, or is it just plain bad driver support? but that can be fixed right?[/QUOTE]It is due to tooo demanding game for current hardware...
Ok. What about Quad core?Most people I talk to say that dual core from Intel is what everyone is using(including mac!!!), so I was wondering if I should get a Dual-core instead of a quad core? whats the difference?

EFI BIOS

Once the PC is turned on, the BIOS will check for almost ALL COMPONENTS. This time, the review process that occurs and how you can speed up your PC with just a few BIOS settings.

Booting a uniform system starting January 11, 1996. Several companies agreed to create a standard BIOS in the "BIOS Boot Specification." Until recently, the standard becomes the operating system for the system (the bootstrap loader) is still used to set the operating system.

When the operating system is always offered with new features, such as the BIOS is still first. That condition was intentional, the manufacturer does not offer a feature i cool "weird" in the BIOS because it is not unusual for these things can cause problems

The latest EFI BIOS supports native 64-bit and has a graphical interface. However, until recently, rarely PC equipped with EFI because it is not compatible with existing motherboards. Only Apple is using BIOS wear this type since 2006. How where you able to install Mac OS on a PC with an EFI-Electric

If all goes well, you will briefly hear "beep". For most users, this signal is a sign that the computer is in good condition and is ready to run PC operating systems. However, there are rarely find out what happened during the first second until the sound of "beep" sound. Power supply, CPU, RAM, hard disk connections, controllers, and motherboards, all checked by the BIOS (Basic Input Output System). This time, we look more closely, what is checked by the BIOS before the computer actually running the operating system.

BIOS that is used by even the newest computer has actually been to the annual age, but still the best. His successor was already available, that is EFI (Extensible Firmware Interface) that supports 64-bit system so it is appropriate for future generations of PCs. Thanks to the graphical user interface, EFI easier than a computer configured with the current BIOS. This new super-new BIOS is used by computers Mac and PC use only slightly worn. How BIOS protocol that is used by almost 90 percent of today's computers, all featured here.

0.0300 seconds

Once the system is turned on, the first stage of the BIOS, the POST-Test (Power-On Self-Test) will be activated. This phase checks the core components of a computer, whether it is functioning correctly. Next, the BIOS will recognize the computers chipset.

1.7300 seconds

The first one was done the BIOS is reset the CPU. Here, the BIOS will decide NM-Interrupt-Line (non mask Able Interrrupt) to the CPU. For that, the BIOS will set the 7th bit in the I / O-Port 70h.

In almost the same time, the keyboard controller is also reset with the appropriate Bits Hard Reset after voltage is available. With Reset-Determination, the BIOS also checks whether the controller will only need a Soft-Reset. For that, the BIOS will read the appropriate bit in the keyboard controller. The advantage, Soft-Reset lasts a few milliseconds faster because the system only up to 64 KByte memory test.

2.6100 seconds

BIOS now examine its own systems by making a checksum consisting of all the bits on the chip. With the numbers that have been determined, the BIOS must produce "2000".

Furthermore, the PC sends an instruction to the keyboard controller. PC will perform other tests and defines a data buffer for programming command. Here, the BIOS will write a command byte and check the internal keyboard controller.

4.1100 seconds

Now, go into the chip CMOS (Complementary Metal Oxide Semiconductor). Here are stored all the user-defined settings for the BIOS. Each time the boot, the BIOS will read the configuration from the CMOS chip. However, the data and settings are only stored in the chip while it is connected to the battery, just like RAM.

Here, the system also test the checksum the CMOS chip, the part that can be written in the BIOS. In addition, a checksum will be made. This process will detect whether a computer battery is damaged. When the battery is weak, the voltage is not sufficient to supply certain components in the CMOS chip. Users will know that user-defined settings in the BIOS and system time is reset.

4.6200 seconds

In a further step, the POST test-Timer Interrupt function of the duty to improve the function of allocating IRQ. IRQs (Interrupt Requests) is a command that will be sent to the CPU, for example by the hard disk or graphics card so that the processor knows that the data for processing already available. This request is always accompanied by the latency time which will adjust the time between the beginning of IRQ-Signal and data processing.

Next, the BIOS set the IRQ Vector-Table and load user-defined settings in the BIOS to the CMOS-Memory. Interrupt-Queries from the very first device received by the Programmable Interrupt Controller then forwarded to the CPU. Then terminate the command processor is running and confirm the interrupt on the Controller.

Then, the CPU read the IRQ numbers (Vector) accordingly from the Controller and use it as an index in the Interrupt-Vector-Table. This table contains the appropriate allocation for each IRQ, for example where the processes that have been implemented specifically for a particular device. Because of the limited number of available IRQ, on modern systems, multiple devices sharing an interrupt (Interrupt Sharing).

The problem is routine for an interrupt that must be executed by any such device drivers that have enabled the interrupt. This can cause problems if the driver is active for too long (because the drivers are not programmed in an optimal). Meanwhile, another device and then write into the buffer, which quickly filled and there will be overflow from a certain time. This process can cause data to be lost.

Therefore, in modern peripheral devices, operating systems provide a dynamic IRQ numbers.

PC Over Tighten: With BIOS Tricks

Better to use the new BIOS instead of buying a new PC. Typically, the BIOS- using Flash-EEPROMS (Electrically Erasable Programmable Read Only Memory) and can be updated through software. However, you must be careful. Upgrading quite risky. When the update process does not run smoothly, your hardware will be damaged. On the other hand, updating the BIOS can provide much faster performance.

BIOS RECOVERY:

Many motherboards are equipped with an emergency system in the BIOS. When the update process is broken, will run system recovery. From here, you can run a file recovery.

BIOS-tuning:

With the right settings in the BIOS, you can increase your PC's performance significantly.

Generally, by making over-clock the CPU. Enter a value in the menu "Advanced | Configuration JumperFree | CPU Frequency", for example 20 MHz higher than those displayed in the BIOS. With this increase, the CPU temperature will not reach more than 60 degrees Celsius, while at peak load, the temperature does not exceed 90 degrees Celsius.

Improved performance was also obtained by setting the appropriate RAM. Go to the menu "Advanced | Chipset | North Bridge Configuration" and lower "CAS Latency" to "3". If Windows can not boot, restore the value to "4". In the same way, change also the value of "RAS # to CAS # Delay" and "RAS # Precharge". Set the "RAS # Activate to Precharge" to value "10". Principally, the lower the value, the faster computer performance.

4.8200 seconds

BIOS will test whether there is an error in the allocation Channel and Channel Address on the first MByte RAM. To that end, samples POST write data into RAM and then compare them. Currently, the system of checking and initializing the video adapter graphics card. First, examine the type of Video Adapter BIOS and run a battery of tests on the adapter and monitor. If any, error messages will be displayed on the screen.

5.0200 seconds

Furthermore, the turn-Controller DMA (Direct Memory Access). CPU and RAM databus connected with the motherboard via a Host-Bridge. Transactions on the bus generally occurs between the bridge and peripheral devices. Peripherals in order to process data quickly and peripherals hostbridge can access directly, without having to go through the RAM. For testing, the BIOS back to using the sample data. The system will write it into memory.

Keyboard device must also be tested. BIOS can now detect the keyboard is not functioning. NumLock button located in the right area of the keyboard will be active.

7.6300 seconds

Now, the BIOS go into the final test. BIOS re-examine the disk drives, hard disk, and connections, before handing control to the system to interrupt the boot loader-19. The task of this interrupt to load the operating system and monitor the hard disk data transfer along with its controller. Many versions of the BIOS to disable IRQ19 offer this feature. However, these features are only effective if the computer is equipped with an additional drive controller, such as a PCI-RAID-Controller.

If there are errors in self-test, beep signal will be sounded several times and error messages displayed on the screen. To understand this BIOS SOS code, a table was available on the Internet (www.computerhope.com / beep.htm). With these tables, you can limit the sources of error. If you want to ensure that components are damaged, you can use a diagnosis Card. This card is inserted into an empty slot on the motherboard and will display the error code in the form of numbers. A code table is used to find the faulty component.

12.4300 seconds

If all goes well, the computer reads only briefly and then look for a bootable operating system on the boot media. When an error occurs here, usually caused by the failure of the MBR (Master Boot Record). You can try to restore the system by running the Windows installation DVD. When a PC using Windows XP, booting with the CD is to install and run the "Repair Console". Then, run the command 'fixmbr' and restart. When using Vista, run the installation DVD and select the option "System Repair" in Setup. If this does not work, do the procedure as in XP and go to Repair Console. Then, run the command "bootrec / fixmbr".

If this method fails, do not immediately decide to reinstall. In Vista, a warning message NTLDR is often marked by the cursor on the screen with berkedipnya who is black. In this case, go to the Repair Console and give the following command:

c:

cd·boot

attrib·c:\boot\bcd·-s·-h·-r

ren·c:\boot\bcd·bcd.old

bootrec·/rebuild

When using Windows 7, you can enter a Bootable DVD and his right boot sector recovery through the Repair feature. Note the BIOS boot sequence correct. Here, IRQ19 will find the right system and run a real operating system.

Mac OS X with EFI-X module, you can install another system on your PC.

Manufacturers are less motivated by this BIOS successor. EFI (Extensible Firmware Interface) has long been applied to the Mac computer, while sis where the PC is still limping along. Hardware vendors, MSI, has two new motherboards equipped with EFI. Meanwhile, the new ASUS video display only those concepts with EFI in November last. !

HOW TO BECOME A PC MAC:

With the EFI-X-Module (www.efi-x.com, about U.S. $ 200) you can use a new version of the BIOS. This module is a special internal USB-dongle that will outwit the computer so that the PC is considered as an Apple computer. Mac OS X can be ins tall on all PCs, although it is not available in EFI-BIOS. Without tricks like this, the installation will not succeed. EFI-X module requires specialized hardware, such as an Intel CPU. In addition, the required computer motherboard from Gigabyte or DFI should. For graphics cards, Nvidia or ATI will suffice. If you want to use the EFI-BIOS module on the USB port, you still require additional adapters that are easily available in computer stores. The price is approximately around U.S. $ 4. Now, you must be running Mac OS X from the installation DVD (www.apple.com). Done.

For information, EFI-X Firmware chip is easy to be updated. Update for the chip can be obtained on the Internet. Later, more hardware components that can be operated with the EFI chip.

Loose Diamonds: The Round Brilliant And Other Cuts

Why purchase loose diamonds? They're not necessarily as practical as earrings and necklaces. You would not be able to have them on you or display them anywhere you go. But diamonds have a beauty on their own that can't be revealed by diamonds set in jewelry. They seem even more special when they are bought for their own sake.

Diamonds are available in a variety of designs, known in the trade as cuts. The most famous of these is the round brilliant cut. Simply put, the round brilliant is the most popular because it provides the most brilliance. It has been cut in such a way that it reflects the most light. What most people don't know is that the shape of the round brilliant is the most uneconomical. As much as half of the original diamond is left out when it is turned into a round brilliant. For this reason, diamonds are sold in several other shapes as well, commonly known as fancy cuts.

Now some of the fancy cuts are already based on familiar designs, and will appeal to people even if they don't know much about diamonds. The heart and oval cuts are self-explanatory. The pear cut is often seen as an upside down teardrop.

On the other hand, how do you explain to people the differences between the Asscher and emerald cut, or the princess and radiant cut, when their shapes are the same? This is where we get a bit technical, but fortunately you don't have to get that esoteric.

Emerald and Asscher cuts are classified as step cuts. Compared to the round brilliant, they are rectangular in shape, with each side bordered with small steps. Step cuts emphasize lustre and clarity over brilliance. The Asscher cut has been popular for over 100 years, and its proportions are less even.

The princess and radiant cuts comprise a third category, known as mixed cuts. They evoke the brilliance of brilliant cuts, but are more practical to produce. The princess cut is the most popular next to the round brilliant, whereas the radiant cut has over 70 cuts.

When choosing loose diamonds, you need not be intimidated by technical knowledge. You can buy based on what cut you like. The jeweler, in turn, will narrow down your choices in terms of price and quality, and help find the best deal for you.

Diamonds are produced in a variety of designs, known in the trade as cuts. The way the round brilliant cut has been cut makes it reflects the most light. Step cuts accentuate lustre and clarity over brilliance. Mixed cuts evoke the brilliance of brilliant cuts, but are more practical to produce. When selecting loose diamonds, you need not be intimidated by technical knowledge. You can buy based on what cut you like.

An exciting range of Carabiner keychains for varied needs & budgets!

Carabiner keychains have emerged as the most popular promotional items in the USA, the UK, and other countries across the world. They are affordable, easily available in a huge variety, and universally used by one and all. Further, the carabiner keychains can be customized with a name, logo, or business message to suit varied marketing needs and objectives of small, as well as, large business units.

If you are planning to use the carabiner keychains as trade show gift items, promotional give aways at sales meet, or to give them as gifts to your employees, you may log on to www.promotionalkeychains.biz The website offers a wide collection of the carabiner keychains in several shapes and styles.

At promotionalkeychain.biz, you may choose amongst custom carabiners with laser engraved logo, name, or business message in star shape, retro sweet heart shape, dollar sign, bear shape, boat shape, house shape, diamond shape, and many others. You may also go for LED safety whistle carabiner keychains, LED squeeze light carabiner promotional key chains, medallion carabiner keychains, compass carabiner keychain, custom PVC strap carabiner keychain, bottle opener carabiner keychain, carabiner keychain with watch, timer, calendar, and many other carabiner keychains in exciting shapes, designs, and themes.

As well as great variety, here you may enjoy great prices too. All carabiner keychains, though of the highest quality, are offered at extremely competitive rates. You may choose the carabiner keychains that appeal you the most.

Most popular Office Pens.

We use many types of pens in our daily life, to be included in notes to write in journals or simply documents every day. There are many brands of pens to choose from, and this article will discuss some of the best pens for office available in the market today.

Waterman Ballpoint Pen
One of the most reliable pens on the market for office, Waterman ball point pen is considered one of the best and most used in thousands of offices around the world. Built with precision technology, this pen office has an ideal balance of weight and grip very well. The ink color and clarity is good in writing this unit is always a breeze. Waterman Ball Point Pen has a refined style and feel, and is a good choice, as it is also very durable.

Pilot Dr. Grip LTD
This gel ink pen is not cheap, about $ 10 for one, but his words are wonderful, and this is the high-end pen for any office, usually used by managers and members of top management level. The LTD, although a gel pen, (which is known to loss) is completely reliable and almost always turns out to be smeared. The grip is almost perfect as silk scrolls and ink on paper. The color
ink is very dark, but still has great attributes.

BIC Intensity
This is another popular type of pen for office using a gel-based ink. This writing instrument glides smoothly, although I had the ability smudging when used on cards with glossy surfaces. In general, this pen is a reliable and inexpensive with a lifetime of impressive.

Waterford Killbarry Guilloche Rollerball Pen
This is not tehnically the run-of-the-mill office pen, but must be included for various reasons: one is solid brass and accented with faceted platinum. It 'nice to have this work of art as an anniversary gift ten years of work by colleagues or the boss. If used, the relay Killbarry Waterford exquisite texture and a feeling of luxury. The ink is dark enough, but very clear and precise on paper. He does look a little like 'a vintage fountain pen, without a pillow or grip. This is a pen used to sign the documents and not to write every day.

Uniball Jetstream Premier
This is another pen office of choice for many companies. This rollerball pen writes so smooth and has a reliable stream of ink because of a good cartridge. The Uniball Jetstream Permier action has flexible and quiet clicks, not annoying like many similar programs have disappeared. It works well for the document-writing and has a good shelf-life. The design is quite clever, but the grip is something that needs to get used to. This pen is definitely for those who make a lot of writing, such as reporting and documentation.

Pentel TKO
This is quite a reliable pen office and has been used for a while 'in many places. The shape is tapered with a tree in a clear ink levels can be observed. Comfort grip is good and easy to control. The color ink is smooth and this is cheap to boot .

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.