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Thursday, 08 February 2007 |
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Digital voice recorders are used as voice memo recorders, and as voice message recorders in portable telephone sets. Various types of digital voice recording and reproducing apparatuses have been developed and practically used. A DVR converts an analog signal representing a voice to a digital signal and records the digital signal in a recording medium when the voice is recorded, and converts the digital signal to an analog signal when the voice is reproduced. In the recording mode, the digital voice system first produces a stream of digital data which represents the audio message signal; this stream of digital data is then recorded on a digital memory. When the digital signal is stored in the storage medium, the digital recorder generally applies a coding technique to compress the volume of data. |
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Friday, 16 February 2007 |
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A camcorder is capable of recording image signals picked-up by a image pick-up device or external input signals supplied from an external input terminal by a video tape recorder (VTR) or playing back video signals recorded by VTR. The commercialization of such small portable video camera/ videotape recorder combinations has made it possible to conveniently, efficiently and inexpensively videotape activities such as sporting events and social gatherings. A camcorder records on magnetic tape the image of an object to be photographed, and is equipped with a display through which the object photographed can be confirmed. A video camcorder has the function of a general video camera for imaging an object as well as the function of a video recorder for recording the image of the object. |
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Friday, 02 February 2007 |
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A ground fault circuit interrupter (GFCI) is a device that is intended to reduce the chance of accidental electrocution by interrupting the power line, when the difference in current is greater than a predetermined level. The ground fault condition results when a person comes into contact with the line side of the AC load and an earth ground at the same time, a situation which can result in serious injury. The GFCI device is operable to enter a de-energized state to isolate an AC load connected to the load side terminals from the line side terminals upon detecting a ground fault condition. GFCIs cut off the supply of electric current to a "hot" surface immediately upon flow of electric current to ground through other than the normal return path of the circuit in which the electrical appliance is connected. |
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Thursday, 01 February 2007 |
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Digital delay generators, or programmable timing units, are electronic circuits used where it is desired to produce a number of signals at precise time intervals. A typical semiconductor device operates by being responsive to a plurality of digital control signals applied to its control signal input terminals. A digital delay generator receives as input samples of an input signal and provides the samples as an output after their respective delays. Digital delay generators are useful in a variety of electronic circuits, such as pulse generators, timing circuits, multiple-phase clock generators, high-speed logic testers and waveform generators. A typical automated test application involves the introduction of a variable delay to a timing edge which is then supplied to a circuit under test. |
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Thursday, 01 February 2007 |
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Circuit breakers are used to protect electrical circuitry from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. Circuit breakers used in residential and light commercial applications are commonly referred to as miniature circuit breakers because of their limited size. A miniature circuit breaker has a thermal-magnetic trip device that opens the circuit breaker contacts in response to persistent current in excess of a predetermined rated current and stops the flow of electrical current through the circuit breaker to the protected electrical equipment. Some miniature circuit breakers include ground fault interruption (GFI) circuitry to protect against ground faults which occur when current flows from a hot conductor to ground. |
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Wednesday, 31 January 2007 |
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Antennas are used to radiate and/or receive typically electromagnetic signals, preferably with antenna gain, directivity, and efficiency. A microstrip antenna is used for the transmission and reception of electromagnetic energy. Microstrip patch antennas are resonant radiating structures that can be printed on circuit boards. Microstrip antennas comprise a radiator element commonly referred to as a patch. Microstrip patch antennas usually comprise just one square or circular metal antenna element attached to a low-loss dielectric substrate. Patch antennas are small, low profile, lightweight antennas that are mechanically robust, simple to manufacture and inexpensive. Accordingly, the patch antenna has many applications in mobile communication systems which require very small, low cost antennas. |
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Wednesday, 31 January 2007 |
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Printed circuit boards are used to make electrical interconnections between leads of electrical components mounted thereon, including processors, memory devices, clock generators, resistors, cooling units, capacitors and other type of electrical components. A PCB involves one or more discrete layers of insulating material upon which patterns of electrical conductors are formed in conjunction with a predetermined array of holes. Multilayer printed circuit boards comprise a stack of layers where layers of conductors are separated from each other by a layer of dielectric material. Chip scale/size package (CSP) refers to an IC package in which the package size is the same as or only very slightly larger than the chip size. The development of CSP technology is very important as high-density mounting advances. |
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Wednesday, 31 January 2007 |
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Solid-state lasers typically include a solid-state lasing medium doped with suitable rare-earth ions that are optically pumped with light emitting from one or more semiconductor diodes to produce coherent light. A laser diode is a light-emitting device based on a light amplification effect. Laser-diode pumping uses semiconductor lasers to replace incoherent optical pump sources such as flash lamps. DPSS lasers have got increasingly popularly used due to their energy efficiency, high reliability, ruggedness, excellent output characteristics, internal blanking and low total cost of ownership (TCO). Accordingly, there is an increasing trend of applying the DPSS laser to industrial applications including laser pointer, machining, material processing, spectroscopy, wafer inspection, light show, and medical diagnostics. |
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Tuesday, 30 January 2007 |
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Lighting quality often determines the quality of a photographic product. A primary purpose of a lighting system is to illuminate a subject to allow proper image capture or achieve a desired effect. Proper illumination is necessary when taking still photographs, whether such activities are carried out indoors or outdoors. Various types of photographic illumination devices are known which provide generally flood lighting. Such apparatus is usually provided to, selectively, provide direct or indirect illumination of the scenes or objects to be photographed. The most common lighting systems in film, commercial, and photographic settings use either incandescent or fluorescent light elements. Light emitting diode (LED) devices have also been used in photography lighting apparatuses. |
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Monday, 22 January 2007 |
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Thermal printers are used in computer systems to print digital images. There are thermosensitive recording type thermal printers and thermal transfer type thermal printers. Thermal transfer printers are used for printing various documents with high resolution and full colors. A color thermal printer prints a full color image on a color thermal recording paper. The color thermal recording paper includes yellow, magenta, cyan thermosensitive coloring layers overlaid in sequence. In a thermal printer, a ribbon is used as a medium for transferring image. The ribbon is unwound from a supply reel and collected on a take-up reel. Platen rollers are used for squeezing print media against a thermal print head to provide proper thermal conduction between the print head and media. |
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Monday, 22 January 2007 |
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Modern vehicles are equipped with electronic control systems to control the components based on information represented by output signals from various sensors for detecting operating conditions. There are a variety of electronic control systems, for example, an ABS (anti-lock brake system), a TCS (traction control system), an ESP (electronic stability program), etc. Vehicle speed sensors are used in motor vehicles to sense vehicle speed and send this information to the vehicle's onboard computer. Wheel speed sensors are typically mounted to a wheel support, such as a steering knuckle, for providing a pulsed speed signal to an antilock brake system. Electrical signals from wheel speed sensors are used by a controller to modulate pressure applied to the vehicle wheels to improve braking performance. |
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