Friday, December 30, 2011
Sunday, December 25, 2011
Understanding Transistor Data and Replacement
If, for some reason, you can't get an exact replacement for the transistor that you want to replace, you can refer to one of the transistor substitution guides or book, and try to identify a "near replacement". Beware, however. A substitution guide will sometimes list a replacement for your part, even though the two parts are not very similar. The most commonly used transistor substitution guides is the Philips ECG semiconductors Master Replacement Guide. Selecting the right transistor parameters or specifications for the equipment you repair will avoid callbacks from customers. Callbacks or repeated repairs due to wrong transistor substitution will cost you extra money and a waste of time.
Some important transistor parameters are:
Maximum collector-to-base voltage (VCBO) - The replacement part should have a VCBO rating equal to or higher than the original.
Maximum collector-to-emitter voltage (VCEO) - The replacement part should have a VCEO rating equal to or higher than the original.
Maximum emitter-to-base voltage (VEBO) - The replacement part should have a VEBO rating equal to or greater than the original.
Maximum collector current (IC) - The replacement part should be able to handle as much (or more) collector current as the original.
Power dissipation (PD Watts) - The replacement part should be able to dissipate as much (or more) power as the original part.
Gain (hFE) - The replacement should have a gain equal to or better than the original and it should be as close to the original specification as possible.
Gain-bandwidth (fT) - the replacement should have a transition frequency equal to or faster than the original and it should be as close to the original specification as possible.
Below is a table of application requirement and important specification that you can use for guidelines when comes to transistor substitution.
Application Requirement and Important Specifications
1. General purpose low level amplifier and switching transistors. Spec- hFE, IC (max), fT, VCEO
2. Power switching applications. Spec- VCEO, VCBO, hFE, IC (max), PD (max)
3. Low level IF/RF amplification. Spec- IC (max), fT, VCEO
4. Audio amplification. Spec- IC (max), PD (max), hFE, VCEO
5. High voltage transistors. Spec- VCEO, VCBO, IC (max), fT
Remember, the replacement transistor should not run hot and if problem still persist, try another replacement number or get the original number if possible. Do not overlook that the surrounding components also may caused the transistor to run hot even if original number is used.
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Wednesday, December 14, 2011
Discount Light Bulbs
There are several stores that carry all major brands of discount lighting. Prices are fixed very competitively in order to entice prospective customers. Both regular and online stores deal in discount light bulbs. Some stores lure customers with weekly special discount offers on light bulbs. Every week certain light bulbs are tagged with heavily discounted prices. These weekly specials are changed frequently, ensuring that some customers become regulars in order to pick up good discount deals.
Purchasing discount light bulbs can be good for maintaining a reserve supply of spare bulbs. A fair amount of window shopping will ensure that you get quality discounted bulbs easily. Discount light bulb dealers stock all varieties of light bulbs like regular household light bulbs, long-life bulbs, reflector bulbs, decorative bulbs, low-voltage bulbs, pool lamps, heat lamps, etc. Several stores offer quality brands at discount prices. They are able to do this due to arrangements with the manufacturer regarding trade volumes and stock lots.
Specialty light bulbs like Christmas lights, medical lights, fluorescent lighting, automotive lights, and halogen lights-you name it, and most discount light stores will have it.
Online discount light bulb stores enable you to compare brands for the best prices and then make a buying decision.
The most popular manufacturers like Carousel, Kodak, Sylvania, Philips, General Electric, Feit, and Westinghouse have arrangements with discount light bulb stores. So, one does not need to compromise quality for discount prices.
Most online stores contain a lot of information about light bulbs, and you can find out about different kinds of bulbs like halogen, fiber optic, fluorescent, automobile, projector, and black light. Information about how they work, what goes into their making, etc., is made available. You can also become familiar with terms like full spectrum, 12 volt, grow lights, ultraviolet, low-voltage, miniature bulbs, and the like.
Saturday, December 10, 2011
The Rapid Pace of Evolution in Consumer Electronics
The evolution of consumer electronics, high definition displays, digital broadcasts, displays and media is happening at an increasingly rapid pace. Advancements in technology are occurring much faster than before, reducing the time to deliver new technologies to market at an exponential rate. The algorithm for designing and delivering new technology is nearly a fifty percent reduction in time with every significant breakthrough. With such a rapid race for invention the simultaneous introduction of diverse technologies is as inevitable as price erosion and shortened life cycles for what is considered "new" in consumer electronics.
A brief history of Television and the advancement of Display Devices underscores the incredibly increasing pace of developing technology.
In 1876 Eugene Goldstein coined the term "Cathode Ray" to describe light emitted when an electric current is forced through a vacuum tube. Fifty years later in 1928, GE introduced the Octagon, a television with a spinning disc and a neon lamp that created a reddish orange picture that was half the size of a business card. By 1948, twenty years later, the demand for black & white television began a transformation in communications and entertainment. By 1949, several familiar brand names fought for a share of the booming market. These brands included familiar names like Admiral, Emerson, Motorola, Philco, Raytheon, RCA, and Zenith. The market was also saturated with brands like Crosley, Du Mont, Farnsworth, Hallicrafters, Sparton and Tele-Tone. In 1951 CBS broadcasted a one hour Ed Sullivan show in color, but there were only two dozen CBS television sets that could process the color broadcast. In 1954, RCA brought the first color television to market, but only 1,000 units were sold to the public that year. In 1956, Time Magazine called color TV the "most resounding industrial flop of 1956".
The Plasma Display Panel was invented at the University of Illinois in 1964 by Donald H Bliter, H Gene Slottow and student Robert Wilson. The original monochrome displays were popular in the early 1970's because they did not require memory or circuitry to refresh the images. By 1983, IBM introduced a 19 inch monochrome display that was able to show four virtual sessions simultaneously. By 1997, Pioneer started selling the first color Plasma televisions to the public. Screen sizes increased to 22 inches by 1992, and in 2006 Matsushita unveiled the largest Plasma video display of 103 inches at the Consumer Electronics Show (CES) in Las Vegas, Nevada.
DLP was developed at Texas Instruments in 1987 by Dr. Larry Hornbeck. The image is created by selective reflection of colored beams of light on a Digital Micromirror Device (DMD Chip). Each mirror represents one pixel on the projected image. The number of pixels represents the resolution. For example, 1920 x 1080 resolution refers to a grid of individual dots of light that are 1920 wide x 1080 high, created from the beam of light reflected off of the same number of tiny mirrors on chip that is smaller than a postage stamp. Concentrated light from a bright Mercury Arc Lamp is beamed through a small rotating color wheel of red, green, blue and sometimes white. The light passing through the color wheel is reflected on the tiny mirrors act independently to point the colored light at or away from the pixel target. The colors perceived by the human eye are a blending of combinations of the red, green and blue reflections in each pixel, and the combination of pixels create the total image. This technology was widely used in Digital Projectors and gradually became a competing technology to Cathode Ray Tube projection television sets, at least until consumers discovered the cost of replacing the high intensity projector lamps.
In 1904 Otto Lehman published a work on Liquid Crystals. By 1911, Charles Mauguin described the structures and properties of liquid crystals. In 1926, Marconi Wireless Telegraph company patented the first practical application of the technology. It was not until 1968 that George Heilmeier and a group at RCA introduced the first operational LCD Display. In December 1970, M. Schadt and W. Helfrich of the Central Research Laboratories of Hoffman-LaRoche in Switzerland filed a patent for the twisted nematic field effect in liquid crystals, and licenses the invention to the Japanese electronics industry for digital quartz wrist watches. By 2004. 40 inch to 45 inch LCD Televisions became widely available on the market, and Sharp introduced a 65 inch display. By March 2005, Samsung introduced an 82 inch LCD panel. Then in August 2006, LG Philips unveiled a 100 inch LCD display. At the Consumer Electronics Show (CES) in Las Vegas, Nevada in January 2007, Sharp once again claimed the top spot for size as they introduced the 108 inch LCD panel under the brand name AQUOS. From tiny liquid crystals to the battle for supremacy and 108" displays, the demand for bigger size and sharper contrast in high definition video has proved once again that Size Matters.
By 2006 there have been more than 220 manufacturers of television sets, and the list is growing just as the types of technology for displays is expanding. Other display technologies include Vacuum Flourescent Display (VFD), Light Emitting Diode (LED), Field Emission Display (FED), not to be confused with K-FED, and Liquid Crystal on Silicon (SED). As the ability to generate and provide high definition broadcast on demand continues to develop, the demand for improved quality and larger displays will continue to increase proportionally. The technology to watch for the next significant leap in high definition and quality image reproduction will be the Surface Conduction Electronic Emitter Display (SED).
So where will the high definition images come from? This pace of technology and battle for formats is racing even faster than the development of the display devices.
Ampex introduced the first commercial Video Cassette Recorder in 1956, with a price tag of US,000. The worlds first Video Cassette Recorder for home use was introduced by Philips in 1972. By 1975, SONY introduced Betamax. The first VHS VCR arrived to market in 1977, JVC's HR-3300, creating a format war that raged for market share during the 19080's. By the 1990's the battle for dominance between VHS and Beta was replaced by a new battle between the MultiMedia Compact Disc from SONY and Philips, versus the Super Density Disc supported by Time Warner, Matsushita, Hitachi, Mitsubishi, Pioneer, Toshiba and Thomson. Amazingly enough, it was Lou Gerstner, president of IBM, who stepped forward and acted as matchmaker to convince the rival camps to collaborate and combine the best of both technologies into a single standard. The result of which became the DVD Consortium, later became known as the DVD Forum. The competing technologies collaborated on standards for manufacturing DVD products with common format until the battle for supremacy was revived in 2006 between HD DVD and Blu-Ray high definition video.
It took 20 years to migrate from a ,000 commercial device to a Video Cassette Recorder for the home. It was almost a 20 year battle in the format war between VHS and Beta, until rival camps under the guiding hand of Lou Gerstner collaborated on a common DVD format. The common DVD format lasted for a mere ten years until the competing technologies once again took the field of battle to claim dominance in the high definition video market, as HD DVD and Blu-Ray fight for supremacy, movie titles, profit and the bragging rights to define the next standard in the evolution of video. At this pace of technology evolution, advancement occurs twice as fast or in half the time of the proceeding era. At this rate we can anticipate the announcement of the next significant advancement in technology and another format within the next five years. Will the next format combine the best technologies of HD DVD and Blu-Ray? Will the next step in evolution be based on utilization of more colors from the spectrum to create even greater definition? Will the format war for storage medium like VHS tapes and Blu-Ray discs become obsolete as the new medium transforms to wireless video streaming on demand? One thing is for sure, it will not take long to find out. Hold on to your VHS movies, compact discs and DVD's, as these will be collector's items and museum pieces before a child born today will graduate from college.
Are you concerned about having the latest technology when you make your next purchase in consumer electronics? Are you worried about selecting the right format, so your library of movies and collection of media will last longer than your pile of LP records and eight track tapes? Choose a display that supports Digital High Definition, learn about the types of INPUTS for your display device or television, and then pick the one that fits your budget. The types of INPUT and connections are important for being able to take advantage of the best display possible from your television or display device. As for recorded media, take your chances on the media that has the most selection of titles and is compatible with your other entertainment devices. There is a good chance that the state-of-the-art technology you purchase today will be obsolete before your extended warranty expires, so sit back and enjoy the evolution.
Words of Wisdom
"The theory of evolution by cumulative natural selection is the only theory we know of that is in principle capable of explaining the existence of organized complexity."
- Richard Dawkins
"Television is the first truly democratic culture - the first culture available to everybody and entirely governed by what the people want. The most terrifying thing is what people do want."
- Clive Barnes
"Any sufficiently advanced technology is indistinguishable from magic."
- Arthur C. Clarke
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Wednesday, December 7, 2011
Light Bulbs - Choosing the Most Energy Efficient
Choosing the right light isn't so easy any more! With the rapid expansion of technology, you're left with dozens of choices, ranging from fluorescent light bulbs, to halogen bulbs, to led bulbs, to the classic electric bulbs invented by Thomas Edison. It's often easy to get lost and settle for the first lights bulbs you find. The next time you're at the store, take a breath, relax, and remember that so much choice is actually a good thing.
Bulbs operate on one of several principles, and can be divided into different types of bulbs. The simplest, and most commonly used are incandescent lights. These are the classic lights we find everywhere around our home, and produce light by passing electricity through a filament, generating both heat and light. They are sometimes called ""daylight bulbs,"" because they produce a very pleasant and warm glow. Halogen bulbs work almost the same way, but are many times more efficient. The filament is encased in a special quartz container, and surrounded with a special gas that allows it to both last longer, and provide more light for the amount of energy you put into it. A 40 watt halogen light bulb may burn as brightly as a 100 watt standard bulb.
But we're getting ahead of ourselves. Take a look at any of them, and you'll probably see some numbers imprinted in the glass. This number is called the bulbs wattage, and it ranges from around 15 watts, to upwards of 10,000. The amount of the bulbs watts determines how much energy it uses. Some lights have a volt and amp measurement, which is really just a different measure of the same thing. Don't be confused when you see an ad for 12 volt light bulbs, or ""low voltage light bulbs."" You can easily figure out the wattage by multiplying the number of volts by the number of amps. For instance, 12v light bulbs that use 6 amps have 12 X 6, or 72 watts.
Another common style of bulbs are flourescent lights. These energy lights don't have a filament at all, but instead pass energy through a tube full of gas. You can see the energy building up in the tube, when you turn the light on and the compact fluorescent bulbs, bulbs flicker before turning on fully. The light emitted by fluorescent bulbs is not the same as that of full spectrum light bulbs, and it may have a cool or unnatural feeling. Still, you can run these lamps bulbs for next to nothing, and they will last for years before needing replacement. Metal halide bulbs are a special type of gas bulb that are often very powerful, and use hundreds or thousands of watts. These lamps are the projector light bulbs commonly found in industrial settings and stadiums.
With energy cost rapidly rising, many people are switching over to low energy bulbs. You can now find many types of energy saver bulbs, that will burn fairly brightly while using a fraction of the watts of standard bulbs. Although energy efficient light bulbs cost more than the ordinary kind, replacing the normal lights in your house with energy saving light bulbs will save you money in the long run. You won't need to change your bulbs as often, and you'll be helping the environment too.
Before you buy any lights online, make sure to check your lamp and verify that the wattage you are buying is the right one for your lamp. Improper wattage may be dangerous, and could potentially start a fire.
Friday, December 2, 2011
Which is More Budget Friendly? The Truth Behind LCD and Plasma TVs!
When one is looking for a television, he will surely encounter the two contending televisions, the plasma and LCD TV. Necessarily, in order to come up with a proper decision, both types of televisions must be compared. Their brands like Samsung, Philips, Panasonic, LG and Sharp shall first be disregarded. These two contending televisions are similar in some ways. One is that they both have super color-filled pictures and they both provide bright crystal-clear images. Another would be they both come in alike packages that is, both their flat screen casing measures 3.50 inches in depth. What really are the issues between the two? The two primary considerations, which are quickly turning out to be a non-issue, are the TV's price and size. If you will notice, LCD TVs are now manufactured in bigger sizes which is priced a bit the same as plasma TVs.
Although both TV technologies are alike in so many ways, there are still differences present between the two while they provide images to their viewers. What comprise a plasma technology are many pixel cells which permits electric pulses, that is, the stemming from electrodes. These pulses stimulate uncommon natural gases such as xenon and neon which causes the same to glow and provide light. The said light elucidates the appropriate balance of red, blue, or green phosphors and the latter are helps in exhibiting the appropriate color sequence originating from the light. Now you know how plasma TV really works.
Each and every flat-panel LCD screens can be found in the hub of the projector. In the same technological background, it is where LCD displays originate. Between two glass sheets, there are liquid-crystal-filled cells which are supplied with voltage by thin-film transistors (TFT) matrix. Once an electrical charge strikes the same, there will be the untwisting of the crystals up to a precise degree in order for it to sift white light coming from a lamp located behind the screen. This is intended for the television's flat panels and for projection via a small LCD chip.
Lesser power is required by LCD TVs in order for it to operate as compared to its plasma counterpart. This is because what is being used by the said television in order for it to exhibit images is florescent backlighting.
It can't be denied that LCD TVs are more expensive than Plasma TVs. Even cheap LCD TVs cannot compare to the cheap price of plasmas. This is so because the former has additional pixels and its production process requires higher costs.
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