When you load a battery into an electronic device, you're not simply unleashing the electricity and sending it to do a task. Negatively charged electrons wish to travel to the positive portion of the battery -- and if they have to rev up your personal electric shaver along the way to get there, they'll do it. On a very simple level, it's much like water flowing down a stream and being forced to turn a water wheel to get from point A to point B.
Whether you are using a battery, a fuel cell or a solar cell to produce electricity, three things are always the same:
1. The source of electricity must have two terminals: a positive terminal and a negative terminal. 2. The source of electricity (whether it is a generator, battery or something else) will want to push electrons out of its negative terminal at a certain voltage. For example, one AA battery typically wants to push electrons out at 1.5 volts. 3. The electrons will need to flow from the negative terminal to the positive terminal through a copper wire or some other conductor. When there is a path that goes from the negative to the positive terminal, you have a circuit, and electrons can flow through the wire.
You can attach any type of load, such as a lightbulb or motor, in the middle of the circuit. The source of electricity will power the load, and the load will perform whatever task it's designed to carry out, from spinning a shaft to generating light.
Electrical circuits can get quite complex, but basically you always have the source of electricity (such as a battery), a load and two wires to carry electricity between the two. Electrons move from the source, through the load and back to the source.
Moving electrons have energy. As the electrons move from one point to another, they can do work. In an incandescent lightbulb, for example, the energy of the electrons is used to create heat, and the heat in turn creates light. In an electric motor, the energy in the electrons creates a magnetic field, and this field can interact with other magnets (through magnetic attraction and repulsion) to create motion. Each electrical appliance harnesses the energy of electrons in some way to create a useful side effect.
Thursday, January 29, 2009
Signal processing
Signal processing deals with the analysis and manipulations of signals. Signals can be either analog, in which case the signal varies continuously according to the information, or digital, in which case the signal varies according to a series of discrete values representing the information. For analog signals, signal processing may involve the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications. For digital signals, signal processing may involve the compression, error detection and error correction of digitally sampled signals.
Signal Processing is a very mathematically oriented and intensive area forming the core of Digital Signal Processing (DSP) and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, TV/Audio/Video engineering, power electronics and bio-medical engineering as many already existing analog systems are replaced with their digital counterparts.
Although in the classical era, analog signal processing only provided a mathematical description of a system to be designed, which is actually implemented by the analog hardware engineers, Digital Signal Processing both provides a mathematical description of the systems to be designed and also actually implements them (either by software programming or by hardware embedding) without much dependency on hardware issues, which exponentiates the importance and success of DSP engineering.
The deep and strong relations between signals and the information they carry, makes signal processing equivalent of information processing. Which is the reason why the field finds so many diversified applications. DSP processor ICs are found in every type of modern electronic systems and products including, SDTV HDTV sets, radios and mobile communication devices, Hi-Fi audio equipments, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio processing and speech processing systems...Just to mention a few of the possibly much more.
Signal Processing is a very mathematically oriented and intensive area forming the core of Digital Signal Processing (DSP) and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, TV/Audio/Video engineering, power electronics and bio-medical engineering as many already existing analog systems are replaced with their digital counterparts.
Although in the classical era, analog signal processing only provided a mathematical description of a system to be designed, which is actually implemented by the analog hardware engineers, Digital Signal Processing both provides a mathematical description of the systems to be designed and also actually implements them (either by software programming or by hardware embedding) without much dependency on hardware issues, which exponentiates the importance and success of DSP engineering.
The deep and strong relations between signals and the information they carry, makes signal processing equivalent of information processing. Which is the reason why the field finds so many diversified applications. DSP processor ICs are found in every type of modern electronic systems and products including, SDTV HDTV sets, radios and mobile communication devices, Hi-Fi audio equipments, Dolby noise reduction algorithms, GSM mobile phones, mp3 multimedia players, camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers, intelligent missile guidance, radar, GPS based cruise control systems and all kinds of image processing, video processing, audio processing and speech processing systems...Just to mention a few of the possibly much more.
Microelectronics
Microelectronics engineering deals with the design and microfabrication of very small electronic circuit components for use in an integrated circuit or sometimes for use on their own as a general electronic component. The most common microelectronic components are semiconductor transistors, although all main electronic components (resistors, capacitors, inductors) can be created at a microscopic level.
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies, compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of quantum mechanics.
Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies, compound semiconductors like gallium arsenide and indium phosphide) to obtain the desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of quantum mechanics.
Electronics
Electronic engineering involves the design and testing of electronic circuits that use the properties of components such as resistors, capacitors, inductors, diodes and transistors to achieve a particular functionality. The tuned circuit, which allows the user of a radio to filter out all but a single station, is just one example of such a circuit. Another example (of a pneumatic signal conditioner) is shown in the adjacent photograph.
Prior to the second world war, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and radar, commercial radio and early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems, computers and microprocessors. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronic engineering.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and power and were limited in speed, although they are still common in some applications. By contrast, integrated circuits packed a large number—often millions—of tiny electrical components, mainly transistors, into a small chip around the size of a coin. This allowed for the powerful computers and other electronic devices we see today.
Prior to the second world war, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and radar, commercial radio and early television. Later, in post war years, as consumer devices began to be developed, the field grew to include modern television, audio systems, computers and microprocessors. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronic engineering.
Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and power and were limited in speed, although they are still common in some applications. By contrast, integrated circuits packed a large number—often millions—of tiny electrical components, mainly transistors, into a small chip around the size of a coin. This allowed for the powerful computers and other electronic devices we see today.
Power
Power engineering deals with the generation, transmission and distribution of electricity as well as the design of a range of related devices. These include transformers, electric generators, electric motors, high voltage engineering and power electronics. In many regions of the world, governments maintain an electrical network called a power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from the grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called on-grid power systems and may supply the grid with additional power, draw power from the grid or do both. Power engineers may also work on systems that do not connect to the grid, called off-grid power systems, which in some cases are preferable to on-grid systems. The future includes Satellite controlled power systems, with feedback in real time to prevent power surges and prevent blackouts.
Power Strips
A power strip refers to a strip of sockets that are attached to the end of a flexible cable and allow multiple devices to be plugged in. Also known as a power board, plugbar, distribution board, it refers to a complete assembly with the power strip on one end and a plug on the other.
Power strips are popularly used in applications requiring AC outlets. This can be with or without surge or line noise protection. These strips can be mounted on racks and walls and also can lie on the ground. The number of electrical outlets in power strips should also be considered necessary for specific applications. These outlet can be configured into a number of styles including NEMA, IEC European standards, CEE European standards, or JIS Japanese standards.
Electrical specificationsThere are certain important electrical specifications that a buyer must consider while selecting a power strip. These are: • Nominal voltages: These can be 24 VDC, 48 VDC, 115 VAC, 208 VAC, or 230 VAC. • Frequency: These can be 50 Hz, 60 Hz or 400 Hz. • Phase: These can be single phase or three phase depending on the application. • Current rating: It refers to the rated current for the power strip, given for maximum continuous current. • Operating temperature It is an important environmental consideration that must also be kept in mind. FeaturesThere are two type of features of power strips. These include: • Protection Features: Such as: o Circuit breaker: These are protective devices used in case of over voltage. These devices trip when there is an overload and may be reset. o Fuse: These safety devices get activated in case of extended over voltage and can be reset. o Thermal sensors: These devices are used for detecting high thermal conditions and also for indicating current overload or other non-design condition.o EMI / RFI protection: This device guards and provides protecting against radio frequency interference (RFI) and electromagnetic interference (EMI). o Transient voltage surge suppression: This refers to clamping or other suppression of transient voltage spikes and other irregularities. • Configuration Features: o AC adapter spacing: This means that outlets are spaced so as to allow insertion of a number of AC adapters. o Battery backup: This means that a battery has a backup for preventing interruption of power in case of power supply failure. o Twist lock plug: It is a safety feature for preventing unintended disconnecting or reconnecting. o On/off switch: This feature allows the unit to be plugged in, but not powered.
Power strips are popularly used in applications requiring AC outlets. This can be with or without surge or line noise protection. These strips can be mounted on racks and walls and also can lie on the ground. The number of electrical outlets in power strips should also be considered necessary for specific applications. These outlet can be configured into a number of styles including NEMA, IEC European standards, CEE European standards, or JIS Japanese standards.
Electrical specificationsThere are certain important electrical specifications that a buyer must consider while selecting a power strip. These are: • Nominal voltages: These can be 24 VDC, 48 VDC, 115 VAC, 208 VAC, or 230 VAC. • Frequency: These can be 50 Hz, 60 Hz or 400 Hz. • Phase: These can be single phase or three phase depending on the application. • Current rating: It refers to the rated current for the power strip, given for maximum continuous current. • Operating temperature It is an important environmental consideration that must also be kept in mind. FeaturesThere are two type of features of power strips. These include: • Protection Features: Such as: o Circuit breaker: These are protective devices used in case of over voltage. These devices trip when there is an overload and may be reset. o Fuse: These safety devices get activated in case of extended over voltage and can be reset. o Thermal sensors: These devices are used for detecting high thermal conditions and also for indicating current overload or other non-design condition.o EMI / RFI protection: This device guards and provides protecting against radio frequency interference (RFI) and electromagnetic interference (EMI). o Transient voltage surge suppression: This refers to clamping or other suppression of transient voltage spikes and other irregularities. • Configuration Features: o AC adapter spacing: This means that outlets are spaced so as to allow insertion of a number of AC adapters. o Battery backup: This means that a battery has a backup for preventing interruption of power in case of power supply failure. o Twist lock plug: It is a safety feature for preventing unintended disconnecting or reconnecting. o On/off switch: This feature allows the unit to be plugged in, but not powered.
How Batteries Work
Batteries are all over the place -- in our cars, our PCs, laptops, portable MP3 players and cell phones. A battery is essentially a can full of chemicals that produce electrons. Chemical reactions that produce electrons are called electrochemical reactions. In this article, you'll learn all about batteries -- the basic concept at work, the actual chemistry going on inside a battery, rechargeable versions, what the future holds for batteries and possible power sources that could replace them.
If you look at any battery, you'll notice that it has two terminals. One terminal is marked (+), or positive, while the other is marked (-), or negative. In an AA, C or D cell (normal flashlight batteries), the ends of the battery are the terminals. In a large car battery, there are two heavy lead posts that act as the terminals.
Electrons collect on the negative terminal of the battery. If you connect a wire between the negative and positive terminals, the electrons will flow from the negative to the positive terminal as fast as they can (and wear out the battery very quickly -- this also tends to be dangerous, especially with large batteries, so it is not something you want to be doing). Normally, you connect some type of load to the battery using the wire. The load might be something like a light bulb, a motor or an electronic circuit like a radio.
Inside the battery itself, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Electrons flow from the battery into a wire, and must travel from the negative to the positive terminal for the chemical reaction to take place. That is why a battery can sit on a shelf for a year and still have plenty of power -- unless electrons are flowing from the negative to the positive terminal, the chemical reaction does not take place. Once you connect a wire, the reaction starts. The ability to harness this sort of reaction started with the voltaic pile.
If you look at any battery, you'll notice that it has two terminals. One terminal is marked (+), or positive, while the other is marked (-), or negative. In an AA, C or D cell (normal flashlight batteries), the ends of the battery are the terminals. In a large car battery, there are two heavy lead posts that act as the terminals.
Electrons collect on the negative terminal of the battery. If you connect a wire between the negative and positive terminals, the electrons will flow from the negative to the positive terminal as fast as they can (and wear out the battery very quickly -- this also tends to be dangerous, especially with large batteries, so it is not something you want to be doing). Normally, you connect some type of load to the battery using the wire. The load might be something like a light bulb, a motor or an electronic circuit like a radio.
Inside the battery itself, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Electrons flow from the battery into a wire, and must travel from the negative to the positive terminal for the chemical reaction to take place. That is why a battery can sit on a shelf for a year and still have plenty of power -- unless electrons are flowing from the negative to the positive terminal, the chemical reaction does not take place. Once you connect a wire, the reaction starts. The ability to harness this sort of reaction started with the voltaic pile.
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