How Does A Cd Player Work

Writen by William Berg

Today there is a wide range of CD players available for the consumer and choosing the right CD player can feel like an arduous task. Style, quality, design och technical solutions vary greatly between the different players. Some players are portable; others are included in larger sound systems. Some players can only handle one disc at the time; others can easily skip between 50 discs or more. Some CD players are very cheap, others are highly expensive. The list goes on and on. Regardless of which CD player you choose it will however consist of three basic parts that are found in all moderns CD players: a drive motor, a tracking device and a laser and lens system. Another thing that all CD players have in common is that they interpret data that has been stored in the form of elongated bumps on a CD (compact disc).

The drive motor in your CD player is the part that makes the disc spin round and round at a correct pace. The drive motor will gradually adjust the speed, since the correct pace depends on which part of the disc that is currently being interpreted. At some spots, the pace will be no higher than 200 rpm, while at other spots the pace needs to be increased up to 500 rpm. As the disc is rotated round and round by the drive motor, the tracking mechanism will adjust the laser assembly and make it possible for the laser and lens system to focus on the miniscule bumps where data has been stored. The laser is constantly being pushed from the centre and outward over the disc by the tracking mechanism.

The data interpreted by the laser and lens system has been stored in the form of elongated bumps on the surface of the CD. One single bump is very small and no wider than 0.5 microns. The height is greater than 125 nanometres and the length is 0.83 microns or slightly more. All these bumps are very neatly organised at the surface of the CD in the form of a 5 kilometre (3.5 miles) long spiral.

The CD itself is made up by several different layers, including a polycarbonate layer and an aluminium layer. When the laser tries to interpret data that has been stored on the CD, it will first penetrate the polycarbonate layer. The aluminium layer will then reflect the laser beam, and the light alterations will be detected by a special optoelectronic mechanism in the CD player. Since the bumps in which data has been stored reflects light in a different way compared to the areas between the bumps (commonly referred to as "lands"), the CD player can determine exactly which parts of the disc that is made up by bumps and which parts that are not.

If a CD is scratched or injured in any other way, it can be impossible for the CD player to interpret it. Sometimes only a minor part of the data will be skipped, but larger damages can render the entire CD useless. Always store your CD's in a protective casing to decrease the risk of scratches. When you clean your CD's, carefully move your hand from the centre and outwards to the edge rather than just swabbing around. Scratches that occur from a radial movement tend to be less damaging than other scratches.

The information you just read about CD players can be applied to most types of optic drives and can not only help you pick out a CD player for you home but also other types of optic drives such as car CD players and car DVD players.

Buying Advice For Purchasing A New Hdv Camcorder How To Get The Best Deal

Writen by Andrew Lock

If you are in the market for an HDV camcorder, what model should you choose? Ultimately, it depends on what type of shooting you plan to do, the level of experience you posses, and your shooting style.

Each manufacturer has geared their HDV products to different target markets. Weigh up the features that you feel you will most benefit from, and then see which camera fulfils those criteria.

Obviously, budget plays a part too. It's important not to lose sight of the fact that the whole point of the HDV format is to enable you to record High Definition in a cost-effective way. The problem with that is that everyone has a different idea of what is considered 'cost-effective.' Hence, if your ideal camera is out of your price range, you can still step into the world of HDV with a cheaper but capable HDV camera.

Beware of Dodgy Dealers

While we're on the subject of spending your hard-earned money, please don't get sucked in by one of the many advertisers on the Internet who offer HDV camcorders at prices that seem too good to be true. If it sounds too good to be true, it probably is.

The mark-up (profit) on most electronics is fairly small, so it's simply not possible for any legitimate company to offer prices that are considerably cheaper than the norm. Many New York establishments in particular have developed a bad name for shady business practices. They have been known to attract customers with amazing offers for Product X, only to cleverly manipulate them into buying Product Y, on which they make far more profit. Another tactic is to sell camcorders without any power supply, cables, manuals, or accessories.

A further scam is to take payment for a camcorder over the Internet or over the phone, with no intention of fulfilling the order for that product. When you contact the company to find out why your product has not been delivered, they will try and force you into exchanging your order for something else, or only fulfil the initial order if you agree to buy overpriced accessories.

The aim of telling you this is not to scare you, but to make you aware and hopefully prevent you becoming a victim. It's sad that the authorities do not do more to drive these unscrupulous dealers out of business.

A notable exception is B&H Video in Manhattan. They are authorised dealers for various manufacturers and they offer fair prices and good service. Likewise, Edgewise Media based in California offer both competitive prices and outstanding customer service. These companies will take care of you. Of course, they are not alone.

If you are in any doubt about a particular dealer, there is an excellent free service on the Internet which allows you to check independent reviews of a company by individuals who have used them, at: www.resellerratings.com. Read a few reviews and look at the ratings and you'll soon see if a company has a good reputation or not.

If you enjoy getting the best deal on your equipment and software purchases, check out: www.techbargains.com. It's a daily updated list of computer and electronics items that are on sale in stores or on the Internet. If you are considering a purchase, I highly recommend checking out this useful resource before you buy, but always remember to check that the seller has a good reputation.

Andrew Lock is a video producer, consultant and trainer with more than 12 years experience. He has fulfilled video marketing projects for high profile corporate clients such as Sony, Disney, BritishAirways, Merrill Lynch, Royal Caribbean Cruises & others.

Lock is a noted advisor within the video production and film industry, and his articles and books are highly regarded as some of the most insightful and practical.

As a Brit who now resides in the U.S., he's been dubbed by his peers as the 'Simon Cowell' of the video industry - his frank, honest and direct approach is a breath of fresh air to those that seek honest answers.

Lock's latest book, 'How to Shoot, Edit & Distribute HDV' is available direct from the publisher at a special price: http://www.hdvbook.com

How To Select The Right Home Theater System

Writen by T Potter

On the market today are a wide range of home theater systems. They range in size, abilities as well as in price. While you may be a little afraid of that big price tag, you still would like a high quality system. Is there are middle ground? There is and you can take full advantage of it. Here are some tips to help you to find the home theater systems that are right for you as well as right for your budget.

• Name brand isn't everything. One of the most common mistakes is to think that purchasing a name brand product gets you what you want. While it may have all the bells and whistles, it may not as well. You'll need to take a good look at other aspects of the system before selecting based on name brand. If you come across a name brand you are not familiar with, take the time to check it out online. Find out what others think of it.
• Features and size. One of the most necessary aspects to think about are the features of the system. To determine which features you should purchase, you'll want to find out a little more about what you plan to use it for. If you plan to use it for watching DVD's, you'll want surround sound. If you are thinking about a system that pipes music throughout the home, you'll want to insure that the system you choose can do that. Size is important. When you think size, think about the size of the room it will be in, the size of the home in which you are in and the energy it needs. Can you accommodate these things in the system you want at your home?
• Installation. Okay, so we all think it is simple enough to wire the home theater system up, the real life story is that it may just be quite different. And, it will take you a good amount of time. If you plan to purchase a system that is too difficult to install, you'll want to factor into your budget the cost of installation.

The home theater systems that you choose should fit your needs and then they should fit your budget.

Written by T.Potter. Visit Home Theater Central 101 for further information.