What Is Voltage Drop?

 

A multimeter can be used to measure voltage drop.
A multimeter can be used to measure voltage drop.

Voltage drop is a term used to describe any reduction in the supply voltage in a complete electrical circuit. The term may be used to describe a voltage loss across a specific component in the circuit, the voltage loss measured across the entire circuit, or as a broad description of the phenomenon of voltage loss in a circuit in general. All electrical circuits, no matter how simple, present a certain amount of resistance to the flow of electrical current through them. This resistance effectively makes the electrical current work harder, and thus absorbs energy. This expenditure of energy is what causes the reduction in voltage described by the term voltage drop.

For example, a simple circuit can be made up of a 9-volt battery attached to a simple flash light bulb with a small switch. If one were to measure the voltage across the batteries terminals with the switch open, the multimeter reading would be approximately 9 volts. If one were to close the switch and illuminate the bulb, that reading would drop by approximately 1.5 volts. That reduction in voltage is what is known as a voltage drop, and it comes about as the result of the work the battery has to do to illuminate the bulb. Each and every component in a circuit, including the wiring, offers a certain amount of resistance to the flow of electrical current and will cause an associated voltage drop.

In applications that are extremely supply voltage sensitive, such as electronic devices, these voltage losses have to be carefully calculated and the supply voltage adjusted to make provision for them. A 12 volt direct current (DC) power supply, for instance, will typically produce an output of 13.8 volts to accommodate this voltage drop phenomenon. In applications that require very long cable runs, it is common practice to uses fairly heavy cables that present less resistance to the flow of electric current in an attempt to minimize the effects of voltage losses. The total potential loss of voltage in any circuit thus needs to be carefully calculated during the design and specification phase of a project to ensure that the final result meets all requirements.

Any voltage loss in a circuit can, fortunately, be calculated with great accuracy using a voltage drop formula. This makes it possible to achieve consistent and predictable results at the end of an installation. These calculations will differ according to the type of circuit, voltage supply, and components involved and can be extremely complex, often requiring the use of a voltage drop calculator. They do, however, take the guess work of accurately adjusting power supply specifications to accommodate circuit resistance.

 

Source / Courtesy : WiseGeek

What Is Electrical Energy?

On a diesel-electric locomotive, a diesel engine provides power to an electric traction motor that turns the unit's wheels.
On a diesel-electric locomotive, a diesel engine provides power to an electric traction motor that turns the unit’s wheels.

Electrical energy results from the movement of an electrical charge, and is commonly referred to as simply “electricity.” Ultimately, it has its origin in the electromagnetic force: one of the four fundamental forces of nature and the one that is responsible for the behavior of electrically charged objects. Electrical energy is the result of the interaction of subatomic particles with this force. Electricity manifests itself in natural phenomena such as lightning and is essential to life at a fundamental level. The ability of humans to generate, transmit and store electricity is crucial to modern industry, technology and, in most countries, domestic life.

The Origin of Electrical Energy

There are two types of electrical charge, called positive and negative. If two electrically charged objects are brought close to one another, they will experience a force. If the charges are the same — both positive or both negative — the force will act to push the objects away from one another. If they have different charges, they will attract one another. This repulsion or attraction is known as the electromagnetic force, and it can be harnessed to create a flow of electrical energy.

Atoms consist of a nucleus containing positively charged protons, with negatively charged electrons orbiting around it. Protons normally stay put in the nucleus, but electrons can move from atom to atom, allowing them to flow through materials, such as metals, that conduct electricity. A place with an excess of electrons over protons will have a negative charge; a place with a deficit will have a positive charge. Since opposite charges attract one another, electrons will flow from a negatively charged area to a positively charged one if allowed to do so, creating an electric current.

Using Electrical Energy

Electricity is useful both in itself and as a means of transferring energy over long distances. It is essential to various industrial processes, telecommunications and the Internet, computers, televisions and many other devices in common use. It can also be converted into other forms of energy for use in a variety of other applications.

When an electric current flows through a conductor, it generates a certain amount of heat. The amount generated depends on how well the material conducts electricity. A good conductor, such as copper, produces very little. For this reason, copper wires and cables are commonly used to transmit electricity: when heat is produced, energy is lost, so a good conductor minimizes energy loss. Materials that conduct electricity less well produce more heat, so they tend to be used in electric heaters, cookers and ovens, for example.

Electrical energy can also be converted into light. Early arc lights depended on an electrical discharge across a small gap to heat the air to the point where it glows — the same principle as lightning. Later, the filament light bulb was introduced: this relies on the current causing a thin, coiled wire to glow white-hot. Modern, energy-saving light bulbs pass a high voltage current through a thin gas, causing it to emit ultraviolet light, which strikes a fluorescent coating to produce visible light.

When a conducting material, such as a copper wire, is moved in a magnetic field, a current is generated. Conversely, a current flowing through a wire will, if it experiences a magnetic field, produce movement. This is the principle behind an electric motor. These devices consist of an arrangement of magnets and coils of copper wire such that when a current flows through the wire, a turning motion is produced. Electric motors are widely used in industry and in the home, for example in washing machines and DVD players.

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Measuring Electrical Energy

Energy is measured in joules, a term named after the physicist James Prescott Joule. One joule is roughly the amount of energy required to lift a one pound (0.45 kilogram) weight a vertical distance of nine inches (22.9 cm). It is, however, usually more convenient to think of electricity in terms of power, which is energy divided by time, or the rate at which it flows. This gives the possibly more familiar unit of the watt, named after the scientist James Watt. One watt is equivalent to one joule per second.

There are a number of other units that relate to electricity. The coulomb is the unit of electrical charge. It can be regarded as a quantity of electrons — 1.6 x 1019 — since all electrons have the same, very small, charge. The ampere, usually abbreviated to “amp”, is the unit of electric current, or the number of electrons that flow in a given amount of time. One amp is equivalent to one coulomb per second.

The volt is the unit of electromotive force, or the amount of energy that is transferred per unit of charge, or coulomb. One volt is equivalent to one joule of energy being transferred for each coulomb of charge. Power, in watts, is equivalent to volts multiplied by amps, so a five amp current at 100 volts would be equivalent to 500 watts.

Generating Electrical Energy

Most electricity is generated by devices that convert rotational motion into electrical energy, using the same principle as an electric motor, but in reverse. The movement of coils of wire within a magnetic field produces an electric current. Commonly, heat, often generated by the burning offossil fuels, is used to produce steam that powers a turbine to provide the rotational motion. In a nuclear power plant, nuclear energy provides the heat. Hydroelectric power uses the movement of water under gravity to drive the turbine.

The electricity generated at power plants is generally in the form of alternating current (AC). This means that the current is constantly reversing its direction, many times per second. For most purposes, AC works well, and this is how electricity reaches the home. Some industrial processes, however, require direct current (DC), which flows in one direction only. For example, the manufacture of certain chemicals uses electrolysis: the splitting of compounds into elements or simpler compounds using electricity. This requires direct current, so these industries will either require AC to DC conversion or will have their own DC supply.

It is more efficient to transmit electricity through power lines at higher voltages. For this reason, generating plants use devices called transformers to increase the voltage for transmission. This does not increase the energy or power: when the voltage is raised, the current is reduced and vice versa. Long distance transmission of electricity takes place at many thousands of volts; however, it cannot be used in homes at these voltages. Local transformers reduce the voltage to around 110 volts in the USA, and 220-240 volts in Europe, for domestic supplies.

Electricity for small, low power devices is often supplied by batteries. These use chemical energy to generate a relatively small electric current. They always generate a direct current, and therefore have a negative and a positive terminal. Electrons flow from the negative to the positive terminal when a circuit is completed.

 

Source / Courtesy : WiseGeek

What Is an Electric Current?

Electric current is measured using an ammeter.
Electric current is measured using an ammeter.

Electric current is the name for the flow of electrons that makes up the movement of electric charge. Current flows when the voltage on one end of a conductor differs from the voltage on the other end of a conductor. A force that most people deal with nearly every day, flowing current includes lighting, electrical power cords, and the surprising shock that comes from shuffling shoes on carpet in dry weather. This force is measured in units called amperes, also called amps.

A ubiquitous presence in modern life, current can be found flowing through conductors. Conductors include metal like aluminum, copper, and steel, but water can also conduct current. Electric current has proved to be quite useful to people, but it can also pose a danger to life and property. As humans are made up largely of water, this means that they can conduct current as well, which puts them at risk for electric injury if they come into contact with a conductor with an electric charge. They can also be injured if they are in contact with a body of water when it has a charge, even if the water is in the form of a small stream or puddle.

When referring to electric current, it is proper to say that the current flows through a conducting object like a wire or appliance, not in it. Insulation like rubber or ceramic is commonly used to keep current from flowing into nearby conductors. While air acts as insulation for wires that do not have contact with conductors, open-air wires must often be insulated at connecting points like transformers or building entry and exit points.

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An ampere, or amp, is the standard unit used to measure electric current. On paper, amperes can be calculated from coulombs by dividing the coulombs by one second. Amperes in electric current are measured using a tool called an ammeter. In equations, electric current is often referred to as I, which is used to stand for the intensity of current before the term was shortened to electric current.

Lightning is a form of electric current.
Lightning is a form of electric current.

Electric current can cause fire. When it comes in the form of lightning, this force can set fire to foliage and damage buildings. To prevent lightning damage to buildings in areas prone to lightning storms, building owners often install devices called lightning rods that attract the lightning charge to a high metal rod, which redirects and dispels the current underground. Desert electrical storms that produce lightning with no rain can set fire to dry brush that can grow to damage many homes and acres of land.

Voltage measures the energy that is carried by an electric charge. Voltage is measured in volts. The flow of electricity is often compared to the flow of water, and voltage is the electric equivalent of water pressure. The higher the voltage, the faster electrons will flow through the conductor.

Source / Courtesy : WiseGeek

What is Ohm’s Law?

German physicist Georg Ohm uncovered how a material's make up, length and thickness influences how much current will flow through it at a certain voltage.
German physicist Georg Ohm uncovered how a material’s make up, length and thickness influences how much current will flow through it at a certain voltage.

Ohm’s Law is a law used in physics that basically explains how electricity operates properly within a simple circuit. In order to explain the electrical process, the law shows how the three elements of electricity — ampere, resistance, and voltage — work together to create a functioning electrical circuit. The law states that the amount of electrical current, measured in amperes, traveling through a conductor is proportional or equal to the voltage, but is inversely proportional to the resistance in the conductor.

The proponent and the namesake of the law was George Simon Ohm, a renowned German physicist in the early 1800s. While working as a professor at the Jesuit Gymnasium of Cologne in Germany, he experimented with and observed the behavior of electricity in simple circuits with different wire lengths. He described and documented all the results in a book, “The Galvanic Circuit Investigated Mathematically,” which was initially rejected but later acknowledged, leading to the establishment of the Ohm’s Law.

Ohm’s Law can be written in a simple mathematical equation: I = V/R, where I is for the electrical current measured in amperes, V is for the voltage, and R is for the resistance. In this equation, the resistance is usually a constant variable, since its value is not dependent on the amount of electric current, but rather on the materials used to make the circuit, such as the metal wires and the resistor itself. The formula can be expressed in other inversed forms such as V = IR, or R = V/I. These inversed formulas can help find the value of one element if the values of the two other elements are already identified.

There are essentially three “truth” statements that one should remember regarding Ohm’s Law. The first statement is that the value of I will increase or decrease if the value of V increases or decreases, respectively. The second statement is that the value of I will decrease if the value of R increases and the value of V does not change. The third statement is that the value of I will increase if the value of R decreases and the value of V remains the same.

Ohm's Law can be used to find the electrical resistance applied to a circuit by resistors.
Ohm’s Law can be used to find the electrical resistance applied to a circuit by resistors.

 

The principle of Ohm’s Law can be practically applied in appliances and any equipment operated by electricity or a battery. For example, a simple light-emitting diode (LED) needs only 2 volts and .02 amperes to light up, but is connected to a 6-volt battery. This may cause the LED to short circuit, and a resistor is needed to reduce the current. Using the formula R = V/I, one can determine that a resistor containing 200 ohms is needed to control the current coming into the LED.

 

Source / Courtesy : WiseGeek

Get an Understanding of Computer Terms

If you’re upgrading your PCs, you might run into many IT terms and computer-related words and phrases that are difficult to understand. We’re to help you know what you’re getting!

Processor

Also known as ‘chip’ or ‘CPU’, the processor controls everything your computer does. It lets you do several things like work, email and surf – all at the same time. More powerful processors are better for more demanding tasks so get one that performs a little above your current needs.

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RAM

The computer uses random access memory (RAM) to process what the user is doing as they are doing it. This includes multitasking, writing a letter, editing a photo or browsing a web site. 4GB of RAM should be enough for most of your everyday needs, and you can always upgrade and add more RAM later.

Hard Drive

Think of the Hard Disk Drive (HDD) as your computer’s long-term memory. It acts as a filing cabinet for your documents, data, media files and so on. The size or capacity of a hard drive is measured in gigabytes. If you plan on storing a lot of videos and other big files, get a larger hard drive. Another option is to purchase an external USB 2.0 hard drive. Some new notebook PCs now use solid-state drives (SSD) with no moving parts, making them more resistant to shock, quieter and with faster information access.

Processor Number

Acting like a serial number, the processor number differentiates features within a processor family, with a higher number generally indicating more features. You can use this number to verify that your chosen processor includes the features you want. Keep in mind that processor numbers do not work across different processor families.

Intel® HD Graphics

Available as a built-in visual feature on selected Intel® Core™ processors, Intel® HD Graphics enables discrete 3D graphics performance without the added cost of a separate graphics card. You’ll enjoy crisp images with the highest frames per second for mainstream videos.00612012015

Intel® Quick Sync Video

Intel® Quick Sync Video accelerates hardware performance during video editing, burning and sharing to significantly reduce waiting time from hours to just minutes.

Intel® InTru™ 3D Technology

Watch Blu-ray videos in stereo 3D and full 1080p resolution on your computer with Intel® InTru™ 3D Technology.

00712012015Intel® Turbo Boost Technology 2.0

A feature available on selected 4th gen Intel® Core™ processors, Intel® Turbo Boost Technology 2.0 automatically provides an even greater boost of speed to reduce lag time to meet the heavy processing demands of high-end apps.

Integrated Graphics

A graphics component needed to view images. Integrated graphics offers the performance for everyday tasks like watching HD videos, viewing photos and creating presentations. Standard in selected Intel® Core™ processors, integrated graphics improve graphics performance and notebook battery life.

Intel® Clear Video Technology00812012015

Intel® Clear Video Technology delivers higher visual performance for sharper images, richer colour and superior audio and video playback.

Intel® Wireless Display

This built-in visual feature allows you to wirelessly view your personal content, online TV programmes, films and videos on your home TV screen.

00912012015Clock Speed

Just like a stopwatch, clock speed measures how fast your processor performs one activity cycle. A faster clock speed enables your computer to execute instructions more quickly, benefitting most applications from spreadsheets to video editing and more. Clock speed rates are shown in gigahertz (GHz). (See GHz)

Gigahertz (GHz)

A unit to measurement commonly used to express processor speed, also referred to as clock speed. 1 Gigahertz (GHz) = 1 billion cycles per second. A higher number used to mean a faster processor, but advances in technology have made chips more efficient. For this reason it’s not advisable to compare performance based on GHz or clock speed alone. (See Clock Speed)

nm (nanometre)

A unit of measure, a nanometre (nm) is one-billionth of a metre. The transistors on Intel’s latest processors are just 32nm wide, with older models at 45nm and 65nm. The smaller size allows transistors to be packed more densely, leak less energy, produce less heat and switch faster, so processors run faster, use less power and are more energy-efficient.

Intel® Hyper-Threading Technology

Available on selected Intel® processors, Intel® Hyper-Threading Technology makes more efficient use of your processor so you can run demanding applications while maintaining system responsiveness. With this technology, multimedia enthusiasts can create, edit and encode heavy graphics files while running other applications, without losing performance.

Cores and Threads01012012015

Cores and threads go hand-in-hand. Multi-core processors are single chips that contain two or more distinct processors or execution cores in the same integrated circuit. Multi-threading allows each core to work on two tasks at once, letting you do more things at the same time for faster results.

Built-In Visuals

A group of technology features designed to enhance the visual experience delivered by the Intel® Core™ processors. Built-in visual features include Intel® Quick Sync Video, Intel® HD Graphics, Intel® Clear Video Technology and Intel® InTru™ 3D Technology.

Discrete Graphics

This graphics component comes as an additional graphics card. While ideal for high-end 3D designers and video editors, it doesn’t add much performance for most business users. It’s important to note that only more powerful processors can make full use of discrete graphics.

Intel® Smart Cache

A cache is a fast storage area where the processor keeps frequently accessed data. Intel® Smart Cache maximises this data storage. It allows each processor core to utilise up to 100% of the space and pull data faster, improving overall performance for rich media applications and games.

Courtesy: INTEL INDIA

Understanding Wi-Fi Speeds

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Wi-Fi speeds are designated by letter, not by number. Unlike the easy to translate number-as-network-speed designation we find with Ethernet the Wi-Fi designations actually refer to the draft versions of the IEEE 802.11 networking standard that dictates the parameters of the Wi-Fi protocol.

802.11b was the first version widely adopted by consumers. 802.11b devices operate at a maximum transmission of 11 Mbit/s but the speed is highly dependent on signal strength and quality—realistically users should expect 1-5 Mbit/s. Devices using 802.11b suffer from interference from baby monitors, bluetooth devices, cordless phones, and other 2.4GHz band devices.

802.11g was the next major consumer upgrade and boosted the max transmission to 54 Mbit/s (realistically about 22 Mbit/s accounting for error correction and signal strength). 802.11g suffers from the same kind of 2.4GHz band interference that 802.11b does.

802.11n is a significant upgrade to the Wi-Fi standards—devices use multiple-input multiple-output antennas (MIMO) to operate on both the 2.4GHz and relatively empty 5GHz bands. 802.11n has a theoretical maximum of 300 Mbit/s but accounting for error correction and less than ideal conditions you can expect speeds in 100-150 Mbit/s range.

802.11ac is a huge upgrade that brings wider channels (80 or 160 MHz versus 40 MHz), more spatial streams (up to eight) and things like beamforming, which sorta send the waves directly to your device instead of bouncing all around, making things much faster. How much faster? There are some models that can do one gigabit per second. It’s extremely fast.

Like Ethernet, Wi-Fi speeds are limited by the weakest link in the direct network. If you have an 802.11n capable Wi-Fi router but your netbook only has an 802.11g capable Wi-Fi module you will max out at the 802.11g speeds. In addition to the speed limitations there is a very pressing reason for abandoning the oldest popular Wi-Fi protocol 802.11b. You must use the same level of encryption on every device in your network and the encryption schemes available to 802.11b devices are weak and have been compromised (WEP encryption, for example, can be compromised in a matter of minutes by a moderately skilled child). Upgrading your Wi-Fi router and wireless equipment allows you to upgrade your wireless encryption as well as enjoy faster speeds. If you haven’t done anything to secure your router now would be a good time to read our guide to locking down your Wi-Fi network against intrusion.

Also like Ethernet, upgrading to the maximum speed—in this case 802.11n—is best suited for people moving large files and streaming HD video. Upgrading to 802.11n will have a negligible impact on your web browsing speed but will have an enormous impact on your ability to wirelessly stream HD content around your home.

How To Secure Your Wi-Fi Network Against Intrusion

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Insecure Wi-Fi is the easiest way for people to access your home network, leech your internet, and cause you serious headaches with more malicious behavior. Read on as we show you how to secure your home Wi-Fi network.

Why Secure Your Network?

In a perfect world you could leave your Wi-Fi networks wide open to share with any passing Wi-Fi starved travelers who desperately needed to check their email or lightly use your network. In reality leaving your Wi-Fi network open create unnecessary vulnerability wherein non-malicious users can sponge up lots of our bandwidth inadvertently and malicious users can pirate using our IP as cover, probe your network and potentially get access to your personal files, or even worse. What does even worse look like?  In the case of Matt Kostolnik it looks like a year of hell as your crazy neighbor, via your hacked Wi-Fi network, uploads child pornography in your name using your IP address and sends death threats to the Vice President of the United States. Mr. Kolstolnik was using crappy and outdated encryption with no other defensive measures in place; we can only imagine that a better understanding of Wi-Fi security and a little network monitoring would have saved him a huge headache.

Securing Your Wi-Fi Network

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Securing your Wi-Fi network is a multi-step affair. You need to weigh each step and decide if the increased security is worth the sometimes increased hassle accompanying the change. To help you weigh the benefits and drawbacks of each step we’ve divided them up into relative order of importance as well as highlighted the benefits, the drawbacks, and the tools or resources you can use to stress test your own security. Don’t rely on our word that something is useful; grab the available tools and try to kick down your own virtual door.

Note: It would be impossible for us to include step-by-step instructions for every brand/model combination of routers out there. Check the brand and model number on your router and download the manual from the manufacturer’s website in order to most effectively follow our tips. If you have never accessed your router’s control panel or have forgotten how, now is the time to download the manual and give yourself a refresher.

Update Your Router and Upgrade to Third Party Firmware If Possible: At minimum you need to visit the web site for the manufacture of your router and make sure there are no updates. Router software tends to be pretty stable and releases are usually few and far between. If your manufacturer has released an update (or several) since you purchased your router it’s definitely time to upgrade.

Even better, if you’re going to go through the hassle of updating, is to update to one of the awesome third-party router firmwares out there like DD-WRT or Tomato. The third party firmwares unlock all sorts of great options including an easier and finer grain control over security features.

The hassle factor for this modification is moderate. Anytime you flash the ROM on your router you risk bricking it. The risk is really small with third-party firmware and even smaller when using official firmware from your manufacturer. Once you’ve flashed everything the hassle factor is zero and you get to enjoy a new better, faster, and more customizable router.

Change Your Router’s Password: Every router ships with a default login/password combination. The exact combination varies from model to model but it’s easy enough to look up the default that leaving it unchanged is just asking for trouble. Open Wi-Fi combined with the default password is essentially leaving your entire network wide open. You can check out default password lists here, here, and here.

The hassle factor for this modification is extremely low and it’s foolish not to do it.

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Turn On and/or Upgrade Your Network Encryption: In the above example we gave, Mr. Kolstolnik had turned on the encryption for his router. He made the mistake of selecting WEP encryption, however, which is the lowest encryption on the Wi-Fi encryption totem pole. WEP is easy to crack using freely available tools such as WEPCrack and BackTrack. If you happened to read the entire article about Mr. Kolstolnik’s problems with his neighbors you’ll note that it took his neighbor two weeks, according to the authorities, to break the WEP encryption. That’s such a long span of time for such a simple task we have to assume that he also had to teach himself how to read and operate a computer too.

Wi-Fi encryption comes in several flavors for home use such as WEP, WPA, and WPA2. In addition WPA/WPA2 can be further subdivided as WPA/WPA2 with TKIP (a 128-bit key is generated per packet) and AES (a different 128-bit encryption). If possible you want to use WP2 TKIP/AES as AES is not as widely adopted as TKIP. Allowing your router to use both will enable to use the superior encryption when available.

The only situation where upgrading the encryption of your Wi-Fi network may pose a problem is with legacy devices. If you have devices manufactured before 2006 it’s possible that, without firmware upgrades or perhaps not at all, they will be unable to access any network but an open or WEP encrypted network. We’ve phased out such electronics or hooked them up to the hard LAN via Ethernet (we’re looking at you original Xbox).

The hassle factor for this modification is low and–unless you have a legacy Wi-Fi device you can’t live without–you won’t even notice the change.

Changing/Hiding Your SSID: Your router shipped with a default SSID; usually something simple like “Wireless” or the brand name like “Netgear”. There’s nothing wrong with leaving it set as the default. If you live in a densely populated area, however, it would make sense to change it to something different in order to distinguished it from the 8 “Linksys” SSIDs you see from your apartment. Don’t change it to anything that identifies you. Quite a few of our neighbors have unwisely changed their SSIDs to things like APT3A or 700ElmSt . A new SSID should make it easier for you to identify your router from the list and not easier for everyone in the neighborhood to do so.

Don’t bother hiding your SSID. Not only does it provide no boost in security but it makes your devices work harder and burn more battery life.  The short version is this: even if you “hide” your SSID it is still being broadcast and anyone using apps like inSSIDer or Kismet can see it.

The hassle factor for this modification is low. All you’ll need to do is change your SSID once (if at all) to increase recognition in a router-dense environment.

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Filter Network Access by MAC Address:

Media Access Control addresses, or MAC address for short, is a unique ID assigned to every network interface you’ll encounter. Everything you can hook up to your network has one: your XBOX 360, laptop, smartphone, iPad, printers, even the Ethernet cards in your desktop computers. The MAC address for devices is printed on a label affixed to it and/or on the box and documentation that came with the device. For mobile devices you can usually find the MAC address within the menu system (on the iPad, for example, it’s under the Settings –> General –> About menu and on Android phones you’ll find it Settings –> About Phone –> Status menu).

One of the easiest ways to check the MAC addresses of your devices, besides simply reading the label on them, is to check out the MAC list on your router after you’ve upgraded your encryption and logged all your devices back in. If you’ve just changed your password you can be nearly certain the iPad you see attached to the Wi-Fi node is yours.

Once you have all the MAC addresses you can set up your router to filter based on them. Then it won’t be enough for a computer to be in range of the Wi-Fi node and have the password/break the encryption, the device intruding on the network will also need to have the MAC address of a device on your router’s whitelist.

Although MAC filtering is a solid way to increase your security it is possible for somebody to sniff your Wi-Fi traffic and then spoof the MAC address of their device to match one on your network. Using tools like Wireshark, Ettercap, and Nmap as well as the aforementioned BackTrack. Changing the MAC address on a computer is simple. In Linux it’s two commands at the command prompt, with a Mac it’s just about as easy, and under Windows you can use a simple app to swap it like Etherchange or MAC Shift.

The hassle factor for this modification is moderate-to-high. If you use the same devices on your network over and over with little change up then it’s a small hassle to set up the initial filter. If you frequently have guests coming and going that want to hop on your network it’s a hugehassle to always be logging into your router and adding their MAC addresses or temporarily turning off the MAC filtering.

One last note before we leave MAC addresses: if you’re particularly paranoid or you suspect someone is messing around with your network you can run applications like AirSnare and Kismet to set up alerts for MACs outside your white list.

Adjust the Output Power of Your Router: This trick is usually only available if you’ve upgraded the firmware to a third party version. Custom firmware allows you to dial up or down the output of your router. If you’re using your router in a one bedroom apartment you can easily dial the power way down and still get a signal everywhere in the apartment. Conversely if the nearest house is 1000 feet away, you can crank the power up to enjoy Wi-Fi out in your hammock.

The hassle factor for this modification is low; it’s a one time modification. If your router doesn’t support this kind of adjustment, don’t sweat it. Lowering the output power of your router is just a small step that makes it necessary for someone to be physically closer to your router to mess with it. With good encryption and the other tips we’ve shared, such a small tweak has a relatively small benefit.


Once you’ve upgraded your router password and upgraded your encryption (let alone done anything else on this list) you’ve done 90% more than nearly every Wi-Fi network owner out there.

Congratulations, you’ve hardened your network enough to make almost everyone else look like a better target! Have a tip, trick, or technique to share? Let’s hear about your Wi-Fi security methods in the comments.

What is a Customized SBC?

SBC – Single Board Computers

SBCs are off-the-shelf products that can be used to develop end-products or applications for a variety of industries. SBCs come along with integrated software and hardware, which includes SoC, memory, power requirements, real world multimedia and connectivity interfaces such as USB, UART, CAN, HDMI, Ethernet, SDIO, MMC, Analog Audio, display etc. The SBC approach helps system developers to focus on the application specific parts. An extensive range of SBCs based on a variety of microprocessors, memory sizes, supported interfaces and operating systems such as Windows Embedded Compact, Linux, Android etc. are available in the embedded market. This offers flexibility to the users to choose the appropriate SBC based on their cost, features and performance requirements. Low cost SBCs are widely used in academic research projects and in feature specific end-products.

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However, the SBC approach suffers inherently from various drawbacks. First of all, the SBC approach leads to high switching cost to migrate to future technologies. As SBCs comes in standard sizes and real world interfaces, so it is difficult to accommodate future improvements in technology and thus the OEMs need to switch to an entirely new SBC solution. Secondly, customizing a SBC is cumbersome as the processor chipset and surrounding I/O are closely coupled due to the single-board design. Finally, space constrained applications may also struggle to use the standardized SBC available in the market.

The Computer On Module (COM) or System On Module (SOM) coupled along with a baseboard offers an equivalent solution as that of the SBCs. The COM approach separates the complex microprocessor part from the relatively simple I/O part and thus offers flexibility to customize the baseboard part based on the feature and size requirements of the end-product. Furthermore, pin-compatible modules ensure convenient and cost effective way to migrate to future technology.

A Customized SBC is an off-the-shelf embedded solution that is a combination of a COM/ SOM and a carrier board. This combination provides a desirable alternative to SBCs in developing any embedded end-products as the former offers the flexibility and scalability inherent to the COM approach and yet, is a ready-to-use complete embedded solution, one of the main benefits of the SBC approach.

Windows CE
Windows
Linux
Linux
Android
Android
Multicore
Multicore
Touch Support
Touch
Cloud
Cloud
Multimedia
Multimedia

 

 

 

 

 

What is a Computer-On-Module?

A Computer-On-Module (COM) / System On Module (SOM) is a highly integrated embedded computing solution that can be used to design and develop end-products for a variety of industries . The COM/SOM approach offers flexibility to system developers to focus on application development by using an off-the-shelf module that has the generic hardware and software to develop any application. This approach greatly reduces the time-to-market and development cost.

COM/SOM are generally built around microprocessors, system-on-chips, or microcontrollers. They integrate additional devices and peripherals which are needed to realise a fully functional computer, which normally includes RAM, non-volatile storage and power supplies.

They are essentially another layer of abstraction that sits above the SoC (System-on-Chip) concept, providing further integration in areas of hardware and software that are not application specific, but are application agnostic.

  • Optimized for Multicore
  • High-Speed Multimedia Interfaces (PCIe, SATA)
  • Direct Breakout™ for Easy Baseboard Routing
  • Fully Compatible Product Family
  • Small Form Factor
  • Free Support Directly from the Developers
  • 10+ Years Product Lifecycle

Carefully view the following image for the big picture 🙂

What is a Resistor?

Ads by Google Variable Resistor 5 Ohm Resistor Resistor High Voltage Resistor Component Electrical Resistor Series Resistor Resistor Values Standard Resistor Resistor Types Chip Resistors Resistor Calculator Resistor Color A resistor is an electronic component that can lower a circuit’s voltage and its flow of electrical current.
A resistor is an electronic component that can lower a circuit’s voltage and its flow of electrical current.

A resistor is a component of a circuit that resists the flow of electrical current. It has two terminals across which electricity must pass, and it is designed to drop the voltage of the current as it flows from one terminal to the other. Resistors are primarily used to create and maintain known safe currents within electrical components.

Resistance is measured in ohms, after Ohm’s law. This law states that electrical resistance is equal to the drop in voltage across the terminals of the resistor divided by the current being applied. A high ohm rating indicates a high resistance to current. This rating can be written in a number of different ways — for example, 81R represents 81 ohms, while 81K represents 81,000 ohms.

The amount of resistance offered by a resistor is determined by its physical construction. A carbon composition resistor has resistive carbon packed into a ceramic cylinder, while a carbon film resistor consists of a similar ceramic tube, but has conductive carbon film wrapped around the outside. Metal film or metal oxide resistors are made much the same way, but with metal instead of carbon. A wirewound resistor, made with metal wire wrapped around clay, plastic, orfiberglass tubing, offers resistance at higher power levels. Those used for applications that must withstand high temperatures are typically made of materials such as cermet, a ceramic-metal composite, or tantalum, a rare metal, so that they can endure the heat.

Electrical resistance was discovered by German physicist Georg Ohm in the 19th century and has since been measured in ohms
Electrical resistance was discovered by German physicist Georg Ohm in the 19th century and has since been measured in ohms

 

Resistors are coated with paint or enamel, or covered in molded plastic to protect them. Because they are often too small to be written on, a standardized color-coding system is used to identify them. The first three colors represent ohm value, and a fourth indicates the tolerance, or how close by percentage the resistor is to its ohm value. This is important for two reasons: the nature of its construction is imprecise, and if used above its maximum current, the value can change or the unit itself can burn up.

Every resistor falls into one of two categories: fixed or variable. A fixed resistor has a predetermined amount of resistance to current, while a variable one can be adjusted to give different levels of resistance. Variable resistors are also called potentiometers and are commonly used as volume controls on audio devices. A rheostat is a variable resistor made specifically for use with high currents. There are also metal-oxide varistors, which change their resistance in response to a rise in voltage; thermistors, which either raise or lower resistance when temperature rises or drops; and light-sensitive resistors.

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[lightbox full=”http://wingedpost.org/wp-content/uploads/2014/10/01028102014.jpg” title=”Resistors are electrical devices that manage the flow of current through a circuit.”]Resistors[/lightbox]
[lightbox full=”http://wingedpost.org/wp-content/uploads/2014/10/00828102014.jpg” title=”A variable resistor is able to manage flows of electricity at a specific level as well as below that level.”]Variable Resistor[/lightbox]
[lightbox full=”http://wingedpost.org/wp-content/uploads/2014/10/00928102014.jpg” title=”Variable resistors can be adjusted to change the level of resistance.”]Level of Resistance[/lightbox]

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Source / Courtesy : WiseGeek