AC/DC Power Supply

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AC/DC Power Supply
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Direct vs. Alternating Current
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Graph of AC voltage over time
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Period and Frequency

• One cycle of a wave is one complete evolution of
  its shape until the point that it is ready to
  repeat itself.
• The period of a wave is the amount of time it
  takes to complete one cycle.
• Frequency is the number of complete cycles that a
  wave completes in a given amount of time. Usually
  measured in Hertz (Hz), 1 Hz being equal to one
  complete wave cycle per second.
• Frequency 1/(period in seconds)

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Mutual inductance

• Whenever electrons flow through a conductor, a
  magnetic field will develop
• Mutual inductance is where the magnetic flux of
  two or more inductors are linked
• A transformer is a device made of two or more
  inductors, one of which is powered by AC
• If the second inductor is connected to a load,
  power will be electromagnetically coupled from
  the first inductor's power source to that load.

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Transformer transforms AC voltage and current.

• Able to step voltage up or down
• The AC voltage induced in the unpowered
  (secondary) coil is equal to the AC voltage
  across the powered (primary) coil multiplied by
  the ratio of secondary coil turns to primary coil
  turns

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AC Rectification

• Rectification is the conversion of alternating
  current (AC) to direct current (DC).
• A half-wave rectifier is a circuit that allows
  only one half-cycle of the AC voltage waveform to
  be applied to the load.
• A full-wave rectifier is a circuit that converts
  both half-cycles of the AC voltage waveform. The
  resulting DC delivered to the load doesn't
  pulsate as much.

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DC regulated power supply

• 110/220V switchable
• LED indicator
• Offers 3V, 9V and 12V regulated DC
• Maximum output current, 200mA

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Voltage Divider
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Breadboard Practice

• Breadboard a voltage divider and measure voltage
  drops
• Place a load on the voltage divider and measure
  voltage drops

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Voltage Regulating ICs
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LM 7805
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Voltage Regulating ICs

• Function Generate a fixed output voltage
  regardless of changes to input voltage or load
• Three main configurations
• BUCK (Step-down)
• BOOST (Step-up)
• BUCK-BOOST

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Parts List

• Parts You Will Need
• An Altoids Chewing Gum tin
• A 9V battery (151095)
• A 9V battery clip (109154)
• A 7805 voltage regulator (51262)
• A USB socket (161024)
• A small switch (109171)
• A 22kO Resistor (691180)
• Two 27kO Resistors (691201)
• A 39kO Resistor (691243)
• 2 ft hook-up wire (36792)
• Electrical tape (285464)
• Metal shears (to cut the Altoids tin)

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USB Charger
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7805 Pinout