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How CDs Work

How CDs Work. Stefanie Xenakis 2005. History of the CD. * Introduced in 1980s *Patented by Philip and SONY *Goal 1: Large storage space *Goal2: Perfect Copies. CD Material. *Mostly polycarbonate plastic *Impressed with microscopic bumps *Bumps arranged on CD as a spiral.

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How CDs Work

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  1. How CDsWork Stefanie Xenakis 2005

  2. History of the CD * Introduced in 1980s *Patented by Philip and SONY *Goal 1: Large storage space *Goal2: Perfect Copies

  3. CD Material *Mostly polycarbonate plastic *Impressed with microscopic bumps *Bumps arranged on CD as a spiral

  4. CD Material (cont…) *Order of materials: 1) Polycarbonate plastic 2)Thin reflective aluminum layer 3) Acrylic layer for protection

  5. CD Spiral *Starts from inside and goes to outside *Data track 0.5microns wide *1 micron= 1 millionth mm

  6. CD Spiral (cont...) *1.6microns separate one track from each other other *Stretched spiral is 3 miles

  7. CD Bumps/Pits *Minimum .83microns long *125 nanometers high *Nanometer=1 billionth of a meter *”Pits” from our view on aluminum side *”Bumps” at laser’s view

  8. CD Components *CD player reads data *Disc drive has 3 important components that each have a job

  9. 1st Important Component 1)Drive motor- spins disc(200-500rpm)

  10. 2nd Important Component 2)Laser/lens system-focus in on and reads bumps

  11. 3rd Important Component 3)Tracking system-aligns laser to follow track

  12. Laser Focus *Passes plastic layer, reads bumps *Reflects off aluminum to receptor AKA optic-electronic device *Receptor detects changes in reflectivity

  13. Laser Focus (cont…) *Reflectivity on bumps is read differently than the CD lands *Reads 0s and 1s AKA digital signal *Digital signal enters DAC *DAC=digital analouge converter

  14. Laser Focus (cont…) *DAC turns digital signal into sound waves *Sound waves go through AMP to boost sound through speakers *AMP=amplifier

  15. Before the CD

  16. Floppies

  17. Records *Needle called a stylus *Stylus held in place by arm *Simpler version of CD *Instead of laser there’s a needle *Spirals are visible to eye

  18. *Spirals are visible to eye *Amplified through speakers like CD *speed must be exact * Too slow=pitch drops;Too fast=pitch rises Records (cont…)

  19. Bibliography How CDs Work. May 3, 2005. <http://electronics.howstuffworks.com/cd.htm> Tsun-Hui, Yao Tang. Conpact Discs(CDs). May 3, 2005. <http://www.sinc.sunysb.edu/class/cei511/1.html>

  20. Bibliography What is a CD. May 3, 2005. <http://www.gsmcables.i12.con/whatiscdr.htm> Turntable History. May 3, 2005. <http://www.enjoythemusic.com/tablehistory.htm>

  21. About Me My name is Stefanie Xenakis and I am thirteen years old. I am Greek and have been to Greece about 7 times. My birthday is October 28, 1991 and my favorite animal is a monkey. I have three dogs and one cat. All of my dogs are poodles. There names are Tina, Rocky, and Lucy. I play the flute and my favorite sports are volleyball and basketball.

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