Laptop Safety Tips

Laptop is the personal computer for mobile use. But unlike desktop computers, the laptop is always close to the body and it is necessary to know the safety measures to prevent hazards due to fire and heat. Let us see what causes the laptops to overheat. The Processor generates around 80-100 degree heat during its operation.For expelling heat from the Laptop, there is a cooling fan and air vents at the sides and bottom. If any one or both fails to work, heat will accumulate inside. The Laptop battery is Lithium Ion type that has pressurized container with a coil and an inflammable liquid. If the battery over heat due to overcharging or any other reasons, it may create sparks and the inflammable liquid will ignite. If the pressure is too high, the battery may explode.If the heat is too high that can also melt the components inside causing fire and expels toxic fumes.

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Computer Safety Tips

Computer is now an essential part our life and most of us use it in home or office. A three way monitoring is necessary while using the computer. If it is connected to the network and opened, it is necessary to use it cautiously. Since it generates very high amount of radiation, proper precautions to be taken to avoid health hazards. Since the computer generates very high temperature, we have to monitor its status to prevent fire hazards. The following safety tips will help you to use the computer wisely and safely.

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TRIAC in power control systems

TRIAC (Triode for AC) is the semiconductor device widely used in power control and switching applications. It finds applications in switching, phase control, chopper designs, brilliance control in lamps, speed control in fans, motors etc. The power control system is designed to control the distribution level of AC or DC. Such power control systems can be used to switch power to appliances manually or when temperature or light levels go beyond a preset level.

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DIAC in Power Control Systems

The DIAC (Diode for AC) is a kind of diode that conducts only when the current through it reaches a particular level. This is the breakdown voltage or V_BO which can be a momentarily rising voltage. Because of their symmetrical bidirectional switching characteristics, the DIACs are widely used as triggering devices in TRIAC based circuits like lamp dimmer, heat control circuits, motor speed control circuits etc.

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SCR in Power Control Systems

Silicon Controlled Rectifiers are semiconductor devices typically used to control high power coupled with high voltage. Therefore these devices find applications in high voltage AC power control systems, lamp dimmer circuits, regulator circuits etc. SCR also find application in the rectification of high power AC in high volt DC power transmission. The SCR belongs to the family of Thyristors and actually the name SCR is the  trade name of the Thyristor from General Electrics.

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Understanding the Pins of IC 555

IC 555 is the popular Timer Chip used to make timer circuits. It was introduced in 1972 by the Signetics. It is called as 555 because there are three 5 K resistors inside. Inside the IC, there are two comparators, a resistor chain, a flip-Flop and an output stage. IC 555 operates in three modes like Monostable, Astable and Bistable modes. In the Monostable mode (MMV), the IC functions as ‘One shot’ pulse generator. That is, when it is triggered; the output goes high for a period based on the values of the timing resistor and capacitor. In the Astable mode (AMV), the IC works as a free running multivibrator. The output turns high and low continuously to give pulsating output as an oscillator. In the Bistable mode also known as Schmitt trigger, the IC operates as a Flip-Flop with high or low output on each trigger and reset.

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Understanding OpAmps

Operational amplifiers are the basic building blocks of Analogue electronic circuits. They are linear devices with all properties of a DC amplifier. We can use external resistors or capacitors to the Op Amp is many different ways to make them different forms of amplifies such as Inverting amplifier, Non inverting amplifier, Voltage follower, Comparator, Differential amplifier, Summing amplifier, Integrator etc. OpAmps may be single, dual, quad etc. OpAmps like CA3130, CA3140, TL0 71, LM311 etc have excellent performance with very low input current and voltage.

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3rd Anniversary

 Today is the 3rd Anniversary of My Blogging. On 10.4.2010, I just started the blog with one article. I got 3 visits on that day.Now the blog is fully loaded with more than 2000 articles in various subjects. Now there are more than 1500 visits per day and the visits crossed 5 Lakh 3 thousand and 4 hundred in the 3rd anniversary.

Tubular Battery Maintenance

Battery maintenance is very important when we use Home inverters. Generally Tubular batteries are recommended due to its high efficiency and life span. Various makes and types are of batteries are available in the market. . Tubular batteries are recommended to backup UPS and Inverters where environmental conditions are tough and ambient temperatures are common. These are capable of long hours of backup and the life period is around five years.

Pen Computing

The method of computer user interface using Tablet and Pen instead of mouse and key board is known as Pen Computing. Use of touch screen devices like Mobile phones, GPS, PDA etc using the Pen as input is also referred to as Pen Computing. Pen Computing essentially has a Stylus commonly known as the Pen and a hand writing detection device called Tablet. First Stylus called Styalator was used by Tom Dimond in 1957 as the computer input.

Cloud Computing

The system that performs the delivery of computing as a service over the network is the Cloud Computing. It is the service that provides shared resources and software information to the computers. In Cloud computing, computation, software, data access etc are provided to the end users. The end user can access the informations in the network without needing to understand the system’s components and infrastructure. The term cloud is used to represent the Internet system similar to the cloud drawing used in earlier telephone system to give point-to-point data circuits for the Virtual private network.

BIOCOMPUTING

Bio computing is the construction and use of computers that functions like living things or having biological components such as DNA. Bio computing is also used in bioinformatics to assist the biological research. Bio computing uses Bio computers which uses biologically derived molecules such as Proteins and DNA. These are used for computational calculations including data storage, data retrieve, data processing etc.

Touch screen Technology

Touch screen is the modern great looking monitor screen that is becoming a new user interface and industrial standard worldwide. Touch screens are now everywhere and are embedded in Mobile phones, Office instruments, Remote controls, Medical equipments, ATMs etc. Touch screens provide a high level of security from tampering, durability from wear, weather resistant etc.

Neurobics rejuvenate your Brain

Our brain can learn , think and grow through interaction with the environment by perception and action.The human brain has the ability to adapt and rewire itself.During daytime, the brain receives millions of visual, auditory and other information which are processed during sleep to retain them as memory.Heavy workload of the brain makes it tired .Neurobics is the brain exercise using the five senses to rejuvenate the brain cells. Mental stimulation improves brain function and  protects against cognitive decline.

Cross Training improves Memory

Cross training is the simple method to activate the two hemispheres of  brain. The right part of the brain is specialized in Visual and Emotional functions while the left brain is Analytical and Verbal. Based on our job and daily brain activities, either left or right part of the brain remains active while the other side is sleepy most of the time. The cross training will improve the neuronal activities and communication between both the brain halves. If you are a person concentrating in Art work or doing lab work, the right part of the brain is more active. If you are doing mathematics or accounting, your left brain is more active. So if you are a mathematician, doing some art work occasionally will cross train the brain.

Why Mosquitoes bite us?

Definitely, mosquitoes are annoying and they can spread diseases also. Since each mosquito lays thousands of eggs, destroying a mosquito equals destroying thousands of mosquitoes. Mosquitoes have chemo sensors which enable them to detect the humans or any other animal by the odor, heat etc released by the body and also the carbon dioxide exhaled by the humans and the other animals. Mosquito bites are caused only by the bite of a female mosquito. The female mosquito feeds off our blood by piercing the skin with the proboscis, a modified mouth part. While sucking our blood, mosquito deposits some saliva into the skin. The saliva contains anticoagulant proteins that remain in our body and react with the body chemicals, resulting in the characteristic itching and bump. Both Male and Female Mosquito are Plant juice feeders but female mosquito bites human beings to get blood protein for the maturation of their eggs. On the first day of emerging from the pupa, female mosquito do not bite and on the second day, it mates and starts feeding human blood. After two or three days it lays thousands of eggs in water and die off.

Human Pheromones

Pheromones are biologically active substances secreted from the body of animals that elicits physiological and behavioral changes in another individual of the same species. Pheromones are ectohormones released from the body to exert influence on another animal of the same species. The word Pheromone is derived from two Greek words Pheran which means to transfer and Horman to excite. Humans, like other animals also release pheromones from the body, but its quantity is less significant since it has no relevance in communication. Human pheromones do not have to be consciously perceived to affect the recipient, but have been shown to affect our behavior when used at subconscious levels.

Why we are so Happy or Sad?

We have both Pleasure centre and Pain centre in the brain. When there is over stress, the pleasure centre will be in operative so that the normal enjoyable moments will not give any pleasure. In to our brain, millions of messages are passing  daily, of which some are happy messages and others, are sad messages. Brains cells communicate each other through the chemical messengers produced by them to make the body prepared to cope up with the situations. If the messages are happy, then the Endorphin system responsible for the happy mood will be elicited. The sad messages are also carried by the brain messengers which causes mood alteration and  loss feeling. Most nerve centers in the brain are capable of receiving both happy and sad messengers and as long as their input is balanced, everything runs normally.If a person is capable of using these happy messengers wisely, he feels that stress is challenging, fun and enjoyable.Don’t be anxious about the future, and don’t be too much ambitious . A person living in  the real world  will have past, present and future. But a person under stress will not have these . We know past, but we don’t know future. So it is better to live in present.

Human Personality

Human personality is reflected in the way of behavior, daily activities and doing competitive works. Human personality can be classified into Type A, Type B and Type AB personalities according to researchers. Type A behavior (TAB) or personalities have something to do with being competitive and most of them are workaholics. Type B personalities on the other hand are generally patient, relaxed, easy-going . AB personalities have mixed profile and cannot be clearly categorized as either Type A or Type B.

3 Amps Battery Charger.Utility Circuit 2

Here is a general purpose battery charger that can deliver 3 Ampere current at 12 Volts to charge Lead Acid battery or Tubular battery. The Ampere meter provided in the circuit indicates how much current is flowing into the battery. Two LED indicators are included to show the charging status.

Battery Protector for Emergency Lamp.Utility Circuits 1

Emergency lamps do not have a facility to prevent the deep discharge of battery if the lamp remains on during day time. The fluorescent lamp filament also damages if it is glowing in low battery voltage. This causes blackening of the filament side that indicates the damaged filament. So we have to switch off the lamp in the morning and switch it on again in the evening. By adding this circuit in the emergency lamp, you can reduce the job of daily switching. This circuit offers two advantages

1. It prevents unnecessary discharge of battery during daytime
2. It charges the battery only during night. This save energy and prevents overcharging of the battery.

Lead Acid Battery

A lead acid battery is composed of series of plates immersed in a solution of Sulphuric acid. Each plate has a Grid on which the active material is attached. In the negative plate, lead oxide is attached as the active material while on the positive plate, pure lead is attached. All the negative plates are connected together. Similarly all the positive plates are also connected together.

Online and Offline UPS

An Uninterrupted Power Supply is essentially a back-up battery to power electronic gadgets like Computer in the event of a power failure. If it happens, the Gadget will draw power from the UPS and will run the load for a prescribed time depending on the capacity of the battery. The change over time from the mains to battery power is less than 5 milli seconds so that the computer will not shut down. This is essential to protect the data in the computer.

Dropbox sharing

Difficulty in sending full size images through email? Here is a simple solution to share images and videos to anybody through email. Dropbox software provides 2 GB free space for sharing images and videos. Once the Dropbox software is installed in your computer, you can share the folder containing images as a whole within a few minutes. When the recipient opens the internet connection, the folder will be downloaded automatically. Let us see the method of installation of Dropbox and the image sharing method.

E-Safety

Internet and Mobile related Cybercrimes include traditional activities such as fraud, theft or forgery, with the involvement of  a telecommunication system .The word Cyber is derived from the Greek word Kubernetes meaning Steersman which means the control over a thing .It is used in the terms cybersex, cybernetics, cyberspace, cyberpunk, cyber homes and cyber hate, but has been largely surpassed by e- .It is used in the computer or electronic context to denote control of the thing represented by the word it precedes.

Photon Belt and December 2012 phenomenon

There are predictions (or rumors) regarding the total blackness for three days from Dec 23 to Dec 25 2012. The predictions claim that the Universe will face a big change and the sun and earth are going to align for the first time. The earth will shift from the present three dimension to zero dimension and return back to the fourth dimension leading to the formation of a brand new world. The predictions also claims that on 21st December, the earth will enter a still ring called Photonic belt an extraordinary phenomenon that occurs once in 11 million years. A kind of showering with light from outer space. But the scientific world totally discarded such predictions and explains that the Photon belt is physically not possible because it requires the gravitational pull of a black hole with light rays being bent around the black hole forming a photon sphere. More over the Photon belt generating star Alcyone is some 440 light years away and the earth is moving away from the Alcyone. Anyway let us stay away from predictions and see the Photon belt phenomenon.

December 2012 Phenomenon

Lot of confusion… Mayans calendar, Nibiru Cataclysm, Solar Flare, explanations from scientific world… Why Mayans Calendar ends in 21st December 2012. So many beliefs and arguments. What is the reason for this? The Mayan calendar is the Mesoamerican Long Count calendar that is characterized by its non repeating nature. The long count calendar identifies a day by counting the number of days passed since the Mythical creation date corresponds to August 11 BCE 3114 in the Gregorian calendar. The Maya were an ancient civilization of the now called Central America and Southern Mexico. During their heyday, the Mayans have developed some calendars to track the sacred days and also to mark the start and end of cyclical periods. They developed one calendar called Long Count and tracked the future long time periods. A group of people think that the 21st December marks the end of the existing world and rise of a new world. They link the date with Nibiru cataclysm which is the encounter between the Earth and a large planetary object. What actually signifies December 21st? Let us move from beliefs and Archeology to Astrophysics

Micro SD (TF) Card How Stuff Works

Micro SD card (Micro Secure Digital card) is the flash memory card widely used as storage device in Digital camera, Mobile phones, MP3 players etc. The Micro SD format was originally called as T-Flash card before adopted by the SD card association. The Trans Flash (TF) cards and Micro SD cards are identical in format and can be used in devices supporting both cards. But unlike TF card, Micro SD cards have the capability of supporting the NFC ( Near Field Communication) system.

Computer SMPS How Stuff Works

Switched Mode Power Supply uses a switching regulator to convert electric power efficiently. SMPS transfers electric power from a source ( AC mains) to the load by converting the characteristics of current and voltage. SMPS always provide a well regulated power to the load irrespective of the input variations. SMPS incorporates a Pass transistor that switches very fast typically at 50Hz and 1 MHz between the on and off states to minimize the energy waste. SMPS regulates the output power by varying the on to off time using minimum voltage so that efficiency is very higher compared to the linear power supply.

Mayans Calendar How it Works

I am slightly deviating at this moment because everybody in the world is now eagerly discussing about 21st December and the Mayans Calendar. What is this Calendar and what is its importance? Let us see how it works. The Mayans calendar is the Mesoamerican Long Count calendar that is characterized by its non repeating nature. The long count calendar identifies a day by counting the number of days passed since the Mythical creation date corresponds to August 11 BCE 3114 in the Gregorian calendar.Scholars of the Mayan Civilization were expert in Sky watching and they predicted the condition of Sky on Dec 21, 2012. This day will be a Winter Solstice. The Sun is going to exactly overlap with the intersect point of Ecliptic of the Milky Way and Equator.

The Maya were an ancient civilization of the now called Central America and Southern Mexico. During their heyday, the Mayans have developed some calendars to track the sacred days and also to mark the start and end of cyclical periods. They developed one calendar called Long Count and tracked the future long time periods. This calendar starts in 3114 BCE and it marked time in roughly 394 year period known as Baktuns. In one long future cycle, they marked December 21, 2012 as the end of the long cycle. The Mayans wrote that the significant 13th Baktun ends in December 21, 2012. According to Mayans calendar, the Long Count resets to 13.0.0.0.0 on 21.12.2012.

Computer RAM. How Stuff Works

Random Access Memory or RAM is the up gradable type of computer memory that can be accessed easily. It is named as Random access memory because any byte can be accessed without touching the preceding byte. SAM or Serial Access Memory is the opposite type in which the memory is arranged in a series of memory cells that can accessed only in a sequential way. RAM is an essential part of computer and Printers. RAM can be classified into DRAM and SRAM. DRAM or Dynamic Random Access Memory which needs to be refreshed thousands of times per second. SRAM or Static Random Access Memory is faster than DRAM so that refreshing in not necessary. More over the SRAM gives the access time as low as 10 nano seconds compared to the 60 nano seconds of DRAM. But due to the high cost of SRAM, DRAM is commonly used in computers. RAM has volatile memory which will wipe off when the power is switched off. Virtual memory is the method of extending the RAM capacity with a part of the Hard drive and Shadow RAM is another kind of RAM in which the contents of the ROM is copied to read-write memory to reduce the access time. RAM disk is the partitioned region of the physical RAM that can act as a faster Hard disk.

Computer Processor. How Stuff Works

When you think of purchasing a Computer, the first choice you have to make is, the best processor type because the Processing unit is the most important part of the Computer. The speed of computer, performance, multitasking ability, all depends on the processor. The CPU or the Processor is the Brain of computer allowing to process numeric data and executing the instructions stored in the memory. The Processor operates at the speed of an internal clock that sends pulses called Peaks. The clock speed called cycle is the number of pulses per second which  is represented in Hertz. With each peak of pulse, the processor performs a function based on the instruction. The term Cycles Per Instruction or CPI represents the average number of clock cycles required for the processor to execute an instruction. The latest version of processor is the family of Duo Core in which two processing units are present. Core duo was the first series by the Intel and Core 2 Duo is the next version. The Core 2 brand was introduced on July 27 ,2006 comprising Solo, Duo, Quad and Extreme sub brands.

Computer Key Board. How Stuff Works

Keyboard is the essential part of the computer used for the direct human input to the computer. It is a typewriter style device in which the buttons act as electronic switches to provide input to the computer. The common keyboard is the Alphanumeric keyboard with a combination of Alphabetic and Numeric keys. The keys in the keyboard correspond to written symbols, but to produce specific actions, combinations key stroke is necessary. Keyboard produces input for numbers, letters, signs etc. Some keys in the keyboard produce action or function commands. Normally the keyboard is used to type text and numbers in word processor or similar programmes and the interpretation of the keystroke is left to the software. The keystroke is identified by the software in the computer and expresses the data in visible form or as commands. The combination of Ctrl – Alt – Del keystroke opens the windows task manager to close a programme or to shut down the computer. The typical Keyboard consists of numeric keys, Number keys and Character keys and Function keys.

Electroluminescent display.How Stuff Works

Electroluminescence is the Optical and Electrical phenomenon in which a material emits light when current passes through it. This phenomenon is entirely different from the emission of light from bulbs and other light emitting devices. It is resulting from the radiative recombination of electrons and holes in a semi conductor material. The excited electrons then generate Photons which appear as light. LEDs and Phosphor displays are typical examples of electroluminescent lighting.

Flexible Electronics. How Stuff Works

Flexible electronics or Flex circuit is the technology for the assembly of circuits on a flexible plastic substrate such as Polyimide. The Flex circuits can be easily flex or bend during its use. The Flex circuit board is manufactured using Polylithographic technology. The Flex circuits find applications like Camera, Cellphone, Satellites etc. Flex circuits are used as connectors where flexibility is needed and they reduces the space considerably. A common application of Flex circuit is the computer key board. LCD display can also be made using Glass or thin transparent foil as substrate so that the entire system can be flexible. Organic LED (OLED) is used in such displays instead of the back light. The thin film of OLED along with the substrate form a flexible LCD display.

e- Paper. How Stuff Works

e–Paper or Electronic paper is a kind of display technology used to mimic the appearance of an ordinary ink on the paper. Electronic paper displays the content using the reflected light so that reading is comfortable like the reading of a book. The e- Paper devices have large surface and wider viewing angle than other types of displays like LDC and LED displays. E-Paper can give clarity and without fading even in sunlight. Applications of e-Paper technology include e-Reader, Mobile phone display, Electronic bill boards, digital displays in commercial establishments etc. The Electronic paper technology can hold the static text indefinitely without using electricity.

e-Book Reader. How Stuff Works

e- Book Reader or e-Reader is a small sized Tablet like mobile electronic device used to store and read the e-Books and Periodicals. The e-Book reader provides portability and readability especially in daylight. A single e-Book reader is equivalent to many books having hundreds of pages. The e-Book reader has a faster screen capable of high refresh rates so as to make the interaction easy. The e-Book reader uses the electronic paper technology to display the contents on the screen. Electronic paper technology is designed to mimic the appearance of ordinary ink on a paper. Unlike the backlight display screen, electronic paper technology uses reflected light as in the ordinary paper. It makes the reading comfortable like a book reading. Its display is generally black and white and colour e-book reader is rare.

iPad. How Stuff Works.

iPad is a kind of Tablet PC designed and released by the Apple Inc which operates in the Apple’s iOS system. It is similar to the Tablet, the mobile version of the computer with touch screen technology. The products of Apple Inc starts with ‘i’ like iPhone, iPad, iPod etc which is something related to ‘internet’, the idea of Steven.P.Jobs to make a product that has easy access to internet.

The first iPad was released on April 3rd 2010 and now there are latest versions like iPad Mini released on 2nd November 2012. The new versions have virtual key pad and multi touch screen with Wi-Fi connectivity for 3G and 4G. The iPad has facilities like video shooting, snapping and play music, send and receive emails and web browsing. There are different versions of iPad like Original, iPad2, Third generation iPad, Fourth generation iPad and iPad Mini.

Dental Curing Light. How Stuff Works

Dental curing light is used by the dentists for treating tooth cavities or filling root canals. The therapy involves the targeted action of high intensity light such as UV light to generate heat by concentrating it in the target area. To fill the cavities of tooth, adhesive chemicals such as polymer resin is used which is compressed in the cavity using the UV light. The compression makes the adhesive completely adheres to the inner surface of the tooth .With the introduction of LED curing light, comfortable dental therapy is now possible without generating heat.

DNA Chip. How Stuff Works

Electronics is emerging as a new branch called Bionics in combination with biology since there are possibilities to explore the ideas from living organisms. Micro organisms are now considering as the major source for developing DNA chips, Molecular switch etc. This new field is the Synthetic biology.

The DNA chips opened a new era in medical research and medical diagnostics. The DNA chip can provide large quantity of genomic data of microorganisms in a few hours, so that identification of the microbe is very easy. A DNA chip is a” Micro array” of genes attached at fixed locations on a solid support like glass slide or silicon membrane.

DNA Hard Disk. How Stuff Works

Not possible to see now because it is not available in shops. It is a future reality that may emerge as DNA based microprocessor. DNA based computing is an emerging technology using the biomolecule DNA as the data storage molecule. It is possible since DNA is doing data storage in the form of genetic information. If DNA computers emerge, it can store billions of times more data than the present computer. The DNA molecule of genes has the potential to perform calculations many times faster than the present microprocessors. By using the Nanotechnology, it is possible to create Nano computers to replace the Silicon based computers.

Tablet PC. How Stuff Works

Tablet PC or Tablet computer is the small sized PC with all the features of an ordinary Desktop computer. It is named so because of its shape and size and is essentially a mini laptop. It has a rotatable touch screen and operates in Widows and Linux. The concept of Tablet PC was developed by Microsoft in 2001 and now the term Tablet is also used for small touch screen devices functions like a PC.

Credit Card. How Stuff Works

 

The Credit Card and ATM card is a kind of payment card issued by the Bank to the customers as a system of payment. The card allows the card holder to pay for the goods purchased as well as to withdraw money from ATM (Automated Teller Machine) counters. The Credit card is popularly called as Plastic money and is different from a Charge card. The Charge card requires the balance to be paid in full each month while the Credit cards allow the users a continuing balance of debt subject to the interest being charged. ATM card on the other hand is issued by the bank for the account holders to withdraw money from ATM counters without going to the bank. Unlike Debit and Credit cards, the ATM card requires authentication through a Personal Identification Number or PIN. Some banks provide a combined ATM and Debit card called Bank card for easy use in ATM counter as well in Point Of  Sale (POS) transactions.

Router. How Stuff Works

Router is the essential part of the Wi-Fi system that forward data packets across the computer network from the broad band. It is a microprocessor controlled device that is used to connect two or more data lines from different networks. Router functions as a controller for the traffic direction from the network. When the data packet arrives, the router will read the address information for determining its destination. By reading the routing information in its Routing Table, the router then directs the data packet. The router also translates the Data Transmission Protocol for the appropriate protocol of the network and prevents the unauthorized network access with the help of firewall. The router will create a routing table of preferred routes between any two systems which are interconnected.

Wi-Fi System. How Stuff Works

Wi-Fi is the trade mark of the Wi-Fi Alliance and the brand name of products using the IEEE 801.11 family of standards and not the short form of Wireless Fidelity as most of us think. Wi-Fi simply represents the trade mark of IEEE 802.11x. Wi-Fi is the technology that allows an electronic device to transfer data wirelessly using radio waves. It is the WLAN ( Wireless Local Area Network) used in home, office, educational institutions etc to provide wireless networking for the internet access. The common Wi-Fi activated systems like Computer, Mobile phone etc can be connected to the internet wirelessly through the Wi-Fi system. For this, the computer should have a wireless network interface controller called Station. The access point of Wi-Fi- is called Hot spot and may be a wireless Router or Modem. The Wi-Fi usually has a range of 20 meters in indoor applications. The technology of Wi-Fi came into action during 1985.

Computing Mouse. How Stuff Works

Computer Mouse ( Computing Mouse) is the input device of the computer which is a pointing device that detects the two dimensional motion relative to its supporting surface. The mouse has two or three buttons, to control the desktop screen and to provide various commands to the PC. The mouse sometime has a wheel to perform system dependent operations. The motion of the mouse is translated into the motion of the pointer on the display which controls the Graphical User Interface (GUI). Old type mouse has a ball to move on the surface but modern optical mouse uses reflected light to activate the circuitry inside. The Optical mouse has one or more Red LED and a Photodiode detector to accept the reflected light from the LED. The Photodiode detects the mouse movement relative to the underlying surface such as mouse pad or table top. In some mouse, laser is used instead of LED. The driver communicate the mouse movements in standard units called “Mickeys”

Stethoscope. How Stuff Works

Stethoscope is a medical diagnostic tool for Auscultation which is the listening of internal sounds of the body. Auscultation is used to examine the heart sounds, breath sounds, bowel sounds etc. Auscultation requires skill,  clinical experience and a good quality stethoscope. An experienced physician can distinguish normal Lub and Dub sounds of the heart as well as heart murmurs and gallops. In combination with the sphygmomanometer, the Stethoscope is used to measure the blood pressure. The Stethoscope was invented by Rene Laennec of France in 1816. The two-sided stethoscope was invented by Rappaport and Sprague in the early 20th century.

Sphygmomanometer. How Stuff Works

The Sphygmomanometer is the diagnostic device used to measure the blood pressure. Blood pressure is the pressure exerted by the blood on the wall of the artery during its flow. It is meant for keeping constant blood flow throughout the body irrespective of the position. Normal blood pressure is 80 mmHg-120 mmHg in which 80 mmHg is the diastolic pressure when the heart relaxed and 120 mmHg is the systolic pressure when the heart contracts. The diastolic pressure up to 90 mmHg and systolic pressure up to 130 mmHg is treated as normal but the person is in the border line of Hypertension. Usually a BP index is used since the BP may vary slightly depending on the conditions of the body and either systolic or diastolic pressure may be high as in the case of aging. Even if we sit in front of the Physician, our BP may increase slightly due to nervousness, a condition called as “White coat effect”. BP index is calculated by adding systolic and diastolic pressures and then dividing by 2. In normal case it is 120+80 / 2 = 100. Up to 110 is treated as normal. BP measurement on both the arms and periodic measurement are advisable to confirm the Hypertension before going on medication.

Conventional Sphygmomanometer is mercury column based and has an inflatable cuff to restrict the blood flow. It is used in conjunction with Stethoscope to hear the sound during the measurement. Sphygmomanometer was invented by Samuel Siegfried Karl Ritter von Basch in 1881.

Electrocardiograph. How Stuff Works

Electrocardiograph is the Medical diagnostic instrument used to record the electrical activities of the heart. It gives a recorded data in the form of a graph called ElectroCardioGram or ECG. Human heart functions through the electrical impulses produced by the specialized groups of cells called Pace makers (SA node and AV node) located on the right surface of the heart. The electrical signals generated by the pace makers will be available on the surface of skin also. The Electrocardiograph detects these signals and output as a graph. By observing the waveform, it is easy to confirm the variations in the functioning of heart.

MRI Scanner. How stuff works

MRI Scanner is the Medical Imaging device used to image the soft parts of the body especially the Brain. Magnetic Resonance Imaging or MRI is the technique used in MRI scanner to provide the detailed structure of the brain. Unlike CT (Computed Tomography) scanning, MRI uses no ionizing radiation but uses powerful magnetic field to align the nuclear magnetization of hydrogen atoms in the water content of the body. Diseased tissue, such as tumors, can be detected because the protons in different tissues return to their equilibrium state at different rates. By changing the parameters on the scanner ,this effect is used to create contrast between different types of body tissue.Patients with some metal implants, cochlear implants, and cardiac pacemakers are prevented from having an MRI scan due to effects of the strong magnetic field and powerful radio frequency pulses.