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Jonathan Tobin: Defending the Right to a Jewish State

Heather Hale: Compliment your kids without giving them big heads

Megan Shauri: 10 ways you are ruining your own happiness

Carolyn Bigda: 8 Best Dividend Stocks for 2015

Kiplinger's Personal Finance editors: 7 Things You Didn't Know About Paying Off Student Loans

Samantha Olson: The Crucial Mistake 55% Of Parents Are Making At Their Baby's Bedtime

Densie Well, Ph.D., R.D. Open your eyes to yellow vegetables

The Kosher Gourmet by Megan Gordon With its colorful cache of purples and oranges and reds, COLLARD GREEN SLAW is a marvelous mood booster --- not to mention just downright delish
April 18, 2014

Rabbi Yonason Goldson: Clarifying one of the greatest philosophical conundrums in theology

Caroline B. Glick: The disappearance of US will

Megan Wallgren: 10 things I've learned from my teenagers

Lizette Borreli: Green Tea Boosts Brain Power, May Help Treat Dementia

John Ericson: Trying hard to be 'positive' but never succeeding? Blame Your Brain

The Kosher Gourmet by Julie Rothman Almondy, flourless torta del re (Italian king's cake), has royal roots, is simple to make, . . . but devour it because it's simply delicious

April 14, 2014

Rabbi Dr Naftali Brawer: Passover frees us from the tyranny of time

Greg Crosby: Passing Over Religion

Eric Schulzke: First degree: How America really recovered from a murder epidemic

Georgia Lee: When love is not enough: Teaching your kids about the realities of adult relationships

Cameron Huddleston: Freebies for Your Lawn and Garden

Gordon Pape: How you can tell if your financial adviser is setting you up for potential ruin

Dana Dovey: Up to 500,000 people die each year from hepatitis C-related liver disease. New Treatment Has Over 90% Success Rate

Justin Caba: Eating Watermelon Can Help Control High Blood Pressure

The Kosher Gourmet by Joshua E. London and Lou Marmon Don't dare pass over these Pesach picks for Manischewitz!

April 11, 2014

Rabbi Hillel Goldberg: Silence is much more than golden

Caroline B. Glick: Forgetting freedom at Passover

Susan Swann: How to value a child for who he is, not just what he does

Cameron Huddleston: 7 Financial Tasks You Should Tackle Right Now

Sandra Block and Lisa Gerstner: How to Profit From Your Passion

Susan Scutti: A Simple Blood Test Might Soon Diagnose Cancer

Chris Weller: Have A Slow Metabolism? Let Science Speed It Up For You

The Kosher Gourmet by Diane Rossen Worthington Whitefish Terrine: A French take on gefilte fish

April 9, 2014

Jonathan Tobin: Why Did Kerry Lie About Israeli Blame?

Samuel G. Freedman: A resolution 70 years later for a father's unsettling legacy of ashes from Dachau

Jessica Ivins: A resolution 70 years later for a father's unsettling legacy of ashes from Dachau

Kim Giles: Asking for help is not weakness

Kathy Kristof and Barbara Hoch Marcus: 7 Great Growth Israeli Stocks

Matthew Mientka: How Beans, Peas, And Chickpeas Cleanse Bad Cholesterol and Lowers Risk of Heart Disease

Sabrina Bachai: 5 At-Home Treatments For Headaches

The Kosher Gourmet by Daniel Neman Have yourself a matzo ball: The secrets bubby never told you and recipes she could have never imagined

April 8, 2014

Lori Nawyn: At Your Wit's End and Back: Finding Peace

Susan B. Garland and Rachel L. Sheedy: Strategies Married Couples Can Use to Boost Benefits

David Muhlbaum: Smart Tax Deductions Non-Itemizers Can Claim

Jill Weisenberger, M.S., R.D.N., C.D.E : Before You Lose Your Mental Edge

Dana Dovey: Coffee Drinkers Rejoice! Your Cup Of Joe Can Prevent Death From Liver Disease

Chris Weller: Electric 'Thinking Cap' Puts Your Brain Power Into High Gear

The Kosher Gourmet by Marlene Parrish A gift of hazelnuts keeps giving --- for a variety of nutty recipes: Entree, side, soup, dessert

April 4, 2014

Rabbi David Gutterman: The Word for Nothing Means Everything

Charles Krauthammer: Kerry's folly, Chapter 3

Amy Peterson: A life of love: How to build lasting relationships with your children

John Ericson: Older Women: Save Your Heart, Prevent Stroke Don't Drink Diet

John Ericson: Why 50 million Americans will still have spring allergies after taking meds

Cameron Huddleston: Best and Worst Buys of April 2014

Stacy Rapacon: Great Mutual Funds for Young Investors

Sarah Boesveld: Teacher keeps promise to mail thousands of former students letters written by their past selves

The Kosher Gourmet by Sharon Thompson Anyone can make a salad, you say. But can they make a great salad? (SECRETS, TESTED TECHNIQUES + 4 RECIPES, INCLUDING DRESSINGS)

April 2, 2014

Paul Greenberg: Death and joy in the spring

Dan Barry: Should South Carolina Jews be forced to maintain this chimney built by Germans serving the Nazis?

Mayra Bitsko: Save me! An alien took over my child's personality

Frank Clayton: Get happy: 20 scientifically proven happiness activities

Susan Scutti: It's Genetic! Obesity and the 'Carb Breakdown' Gene

Lecia Bushak: Why Hand Sanitizer May Actually Harm Your Health

Stacy Rapacon: Great Funds You Can Own for $500 or Less

Cameron Huddleston: 7 Ways to Save on Home Decor

The Kosher Gourmet by Steve Petusevsky Exploring ingredients as edible-stuffed containers (TWO RECIPES + TIPS & TECHINQUES)

Jewish World Review

How CDs work

By Marshall Brain

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http://www.JewishWorldReview.com | (MCT) In 2007 we are celebrating an important event - it's the 25th anniversary for the CD, also known as the compact disc. In 25 years CDs have become ubiquitous, to the point where we take them completely for granted. But inside a CD you find both an amazing amount of technology.

To understand just how profound the effect of the CD has been, it is helpful to look back at the two reigning technologies in the early 1980s: The vinyl LP and the compact cassette. You may recall just how bizarre the vinyl LP was. An aficionado would have a massive turntable with little black and white markings along the edge so that he could calibrate the speed of the turntable with a strobe light. The turntable rested on big vibration-dampening pads to try to keep any spurious vibrations away from the turntable. The tip of the tone arm was measured with a sensitive scale to minimize its pressure in the record's groove. The LP itself was sprayed with an anti-static gun to cut back on dust. And even with all this technology, the first thing you heard from any vinyl disk was hiss. With the cassette the story was the same: the tape stretched, it flaked, it broke, it jammed.

Enter the compact disc. Because of its digital nature, its sound quality was amazing compared to vinyl or tape. It also eliminated hiss once and for all. Things like dust, fingerprints and small scratches didn't matter. The sound did not degrade over time as it did with vinyl or tape. And normal heat levels, as in a locked car on a hot summer day, didn't cause any problems. And there was an added bonus - over time, compact discs became incredibly inexpensive to produce. How inexpensive? So inexpensive that AOL could afford to mail out billions of them.

The thing that is so amazing about a CD is its simplicity. A CD is basically a mirror. The mirror is made out of a tough, clear plastic disc. A microscopic layer of aluminum is coated onto the plastic to create a mirror surface. To store the CD's data, the mirror has millions of tiny blemishes on it. When a laser hits the CD's aluminum surface, it either reflects cleanly off the mirror or scatters off a blemish. A computer inside the CD player interprets the reflections and scatterings as the ones and zeros of the computer binary code, and reassembles the ones and zeros into music (or data). That is the essence of a CD.

The process of making a music CD goes something like this. The songs of the CD are recorded using a microphone. The microphone picks up vibrations in the air. Those vibrations can then be digitally sampled. For a CD, a device called an analog-to-digital converter (ADC) samples the vibration pattern 44,000 times per second. Based on the intensity of the vibration pattern at the moment it is sampled, the ADC assigns a number between -32,767 and 32,768. Approximately 158 million of these ADC samples make up all the music on a 60-minute CD.

Now these 158 million numbers are turned into ones and zeros. Things like track information and error correcting codes are added. All the ones and zeros are placed end to end to formed a single microscopic spiral track that is about three miles long. This track is placed on a metal mold - a tiny bump on the metal represents a one, and a tiny flat area represents a zero.

To make a CD, liquid plastic injects into the mold and it picks up the pattern of microscopic bumps and flats. Once the plastic comes out of the mold, a layer of aluminum coats the bumps and flats on the plastic. The flats reflect a laser perfectly, while a bump scatters a laser beam. To read the CD, all the CD player has to do is read the ones and zeros, reassemble them into numbers and run the numbers through a digital-to-analog converter. Out comes music.

You can see why CDs are so inexpensive to produce. Each CD is nothing but a blob of liquid plastic injected into a mold, along with a milligram of aluminum. A coat of lacquer protects the aluminum and holds the CD label. There really is nothing to a CD.

In the early 1990s, music companies sold more than 440 million cassette tapes per year. Last year, the number had fallen to 700,000. That shows you just how thoroughly the CD has dominated the musical landscape. Of course, the days of the CD are now numbered - compact discs will be replaced by digital music players that use only the music's data, without any need for the plastic and aluminum.

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Previously:


How the Edsel worked
How Stinger missiles work
How hybrid cars work
How sharks work
How mosquitoes work
How diesel engines work
How water towers work
How the Dawn mission works
How Kassam rockets work
How the North American Eagle works
Why aren't we flying to work?
How tofu and soy milk work
How Colony Collapse Disorder works
How airbags work
How the U.S. income tax works
How gum works
How caffeine works
How Daylight Saving Time works
How a cruise missile works
How snow making works

© 2007, How Stuff Works Inc. Distributed by McClatchy-Tribune Information Services.

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