Transcript Ipod Technology - Goucher College

iPod Technology
Why Won’t My iPod Work?
What is an iPod?

60 GB Portable Media Center
 Holds Movies, Songs and Pictures in MP3
format
 Variations of the iPod include:
– iPod Shuffle- 512MB or 1 GB audio storage
– iPod nano- 1, 2, 4 GB digital audio and photo
storage
– iPod Mini- 4, 6 GB audio storage
www.apple.com
Types of iPods
Shuffle
Nano
iPod Video
Mini
www.apple.com
MP3 Players

Transfer data from a computer using the
computers USB port, FireWire port or parallel
port.
 Information is then saved using either solid
state memory or onto a hard drive:
– Internal Flash Memory
Solid state memory devices are favored because
they do not contain any moving parts in the
memory encoding and are electronically powered.
-semiconductors made of thin
films
www.computerhope.com/jargon/s/solimemo.htm
Flash Memory

Uses ROM (Read-only Memory)
– Integrated circuit programmed with specific data
– Non-volatile-memory isn’t lost when power is
removed
• Used as a back-up storage device for computers
– Data storage is unchangeable or requires a
special operation to change
http://electronics.howstuffworks.com/mp3.htm
iPod Shuffle and
iPod Nano
Uses a EEPROM Flash Memory
-Lighter
-Stores fewer songs
-Long lasting batteries
-Solid state memory
EEPROMs
-Electrically erasable programmable read-only memory
-Data is written or erased one byte at a time
-In other flash memories, data must be written or erased
in one block at a time
http://electronics.howstuffworks.com/ipod7.htm
www.apple.com
How EEPROM Works

There are two transistors separated by thin
oxide layer
- n-type Metal-Oxide Semiconductor Field Effect
Transistor (n-MOSFET)
Changes in the position of the gate caused by the
increase or decrease in voltage programs the cell
value. Information is encoded by the combination of
1 and 0.
Review of P-N
Junction
www.interq.or.jp/japan/se-inoue/e_ckt30_6.htm
When a charge is
applied, the electrons in the
N-type are pulled into the
p-type through the boundary
of the junction to form a
negative ion with the holes.
Filling a hole makes a negative ion
and leaves behind a positive ion on
the n-side. This build up of charge
creates a depletion region which inhibits electron transfer unless a
forward bias is applied. A forward bias is an applied voltage in the
forward direction, assisting electrons to overcome the barrier of
the space charge in the depletion region.

http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/pnjun.html
n-MOS FET
When voltage is not applied to the gate, there is no current flow
between the drain and then source. The cell is then in the 1
position.
www.interq.or.jp/japan/se-inoue/e_ckt30_6.htm
When a positive voltage is applied to the gate of the N channel.
The electrons of the source and drain are then attracted to the
gate and go into the P channel semiconductor. The movement
of electrons acts like a bridge for electrons to move from the
drain into the source. This movement of the bridge caused the
cell to be in the 0 position.
iPod Mini and iPod
Video

Use hard drive as
 Benefits:
memory system.This
– Low level of
recording noise.
uses perpendicular
– Able to store 10
magnetic recording.
times as much
information as a
flash drive.
http://www.amazon.com/gp/product/B0001A99LK/ref=dp_variations_3/102-5619421-0964114?%5Fenco
http://electronics.howstuffworks.com/ipod7.htm
Perpendicular Magnetic
Recording
-Multi-layered magnetic film
composed of ferromagnetic
metal layers of Co alloy
containing Cr and
non-magnetic metal layers of
Pd alloy. This layer makes up
the platter.
-The layered structure reduces the magnetic exchange interaction
between magnetic particles and allows the moment to remain the
same direction. Hard drives store information by changing the
polarization of microscopic magnetic bits aligned end-to-end on a
platter
www.komag.com/technology/perpendicular_pmr.html
www.popsci.com/popsci/bown2005/computing

Microprocessor monitors
all user input through
playback controls,
displays information about
the current song and
sends directions to the
DSP (digital signal
processor) chip about how
to process the audio.
 DSP pulls data from the
memory, amplifies effects
and sends it to the
amplifier.
– Runs a decompression
algorithm that encodes the
compression of the original
MP3 file.
– The amplifier sends the
electrical signal to the
speakers via a cord.
http://electronics.howstuffworks.com/mp3-player2.htm
Earbuds

Receives messages from the amplifier and re-interprets it into physical
vibrations.
 The driver produces sound waves by rapidly vibrating a flexible piece
of paper, metal or plastic called a cone or diaphragm.
– To cause the cone to move, a voice coil is attached to the bottom.
The coil acts as an electromagnet. The electromagnet consists of a
with a piece of magnetic metal with iron wrapped around it.
A current is sent through the
wire creating a magnetic field
with the iron. Unlike a
permanent magnet, the poles
can be switched. This switching
of electric flow is characteristic of
a stereo signal.
http://howstuffworks.com/speakers.htm
Earbuds Continued…
Inside the speaker there
is also a permanent magnet.
The electromagnet and the
permanent magnets are attracted
to each other depending on the
current flow in the electromagnet.
When the orientation of the current switches so does
the direction of the repulsion and attraction. The
alternating current constantly reverses the magnetic
forces between the voice coil and the permanent
magnet. This pushes the coil back and forth rapidly.

http://howstuffworks.com/speakers.htm
Sources
www.apple.com
http://howstuffworks.com/speakers.htm
www.computerhope.com/jargon/s/solimemo.htm
www.interq.or.jp/japan/se-inoue/e_ckt30_6.htm
http://electronics.howstuffworks.com/mp3-player.htm
http://electronics.howstuffworks.com/ipod7.htm
http://www.amazon.com/gp/product/B0001A99LK/ref=dp_variations_3/102-5619421-0964114?%5Fen
www.komag.com/technology/perpendicular_pmr.html
www.popsci.com/popsci/bown2005/computing
http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/pnjun.html