Audio Logistics II

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Audio Logistics II

• Basic electronic components

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What we need to know for this course

• Voltage
• Current
• Resistance
• Capacitance
• Inductance
• conductors, insulators and semiconductors

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Conductors

• Wires or other metals
• Allow for the easy motion of electrons

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Insulators

• Opposite of conductors.
• Inhibits electron flow.

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Semiconductors

• In between insulators and conductors
• One can control the flow of electrons

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Current

• The amount of charge (electrons) flowing past a
  point per second.
• Measured in Amperes or Amps (A)
• The symbol is I

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Voltage

• Is the potential energy per charge beween two
  points
• Relates to the potential intensity of electron
  flow.
• The higher voltage the more energy (and more
  electrons) to make the current flow.
• Measured in Volts (V).

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What provides Energy?

• A battery is a storage device for energy
• One terminal is loaded with electrons.
• The other needs electrons really badly (ions).
• The voltage is the difference in energy levels of
  the terminal with negative electrons and the
  terminal with positive ions.

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Conductor

• The medium the electrons make the jump from one
  terminal to the next is the conductor.

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Resistance

• Electrons try to flow as quickly as they can.
• Resistance hinders the flow.
• Conductors arent 100 efficient.
• There is always some resistance.
• Resistance causes a voltage drop across the
  length of the current flow
• Resistance is a part of Impedance (constant value
  for different frequencies)
• Measured in Ohms (W?

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Resistors
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Potentiometers

• Variable resistors.
• A wiper glides over an element thus changing
  resistance.

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Capacitance

• The ability to store energy.
• Two metal plates separated by an insulator that
  when charged create an electric field.
• Draw energy in charging
• Let energy out discharging
• Allows AC through (reacts differently to
  different frequencies)
• Blocks DC
• Capacitance is measured in Farads (F)
• Reactance (capacitive) part of Impedance(Z)
• Reactance symbol is X and measured in Ohms

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Capacitors

• Fixed or variable.
• Electrolytic caps must be inserted according to
  its polarity.

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Inductors

• Basically, a coil of wire.
• Sometimes referred to as coils.
• Provides opposition to varying current.
• So, works opposite to capacitors, passes DC
  current, hinders AC.
• Measured in henries (H).
• Reacts differently to different frequencies
• Reactance(Inductive) part of Impedance(Z)
• Reactance symbol is X and measured in Ohms
• Fixed or variable.

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Transformers

• A type of inductor.
• Two coils placed in close proximity can either
  step up AC voltage or step it down.
• Blocks DC.

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Transformers
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Diodes

• Allows current to flow in one direction but not
  the other.
• Converts AC current into DC.
• There is a positive (anode) and negative
  (cathode) terminal.

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Transistors

• Amplifies small AC signals. (Adds energy)
• Switches DC voltages.

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Electronic Measurements

• One can measure the voltage, current and
  resistance.
• For a single value measurement use a Digital
  Multimeter (DMM)
• Voltage is measured across a component from one
  terminal to another.
• Current is measured with the DMM in the circuit.
• Resistance is measured with power off and
  component isolated

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Voltage Measurement

• Across components
• There is an AC or DC switch
• Various scales. One needs to know the max voltage
  expected
• The power of the electronic circuit needs to be on

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Current Measurements

• In series with the components
• one measures current through a network branch
• There is an AC or DC switch
• Various scales. One needs to know the max current
  expected
• The power of the electronic circuit needs to be
  on
• Current kills (10mA can kill you)

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Resistance Measurements

• The power has to be off on the electronic device
  being measured
• The component has to be isolated at one end.
• DMM provides own power
• When just measuring connectivity a DMM with
  buzzer is sufficient. (for cables)

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Ohms Law

• Relationship between V, I, Z (R and X)
• X XL -XC
• If we known two of the values we can calculate
  the third
• VIxZ, IV/Z, ZV/I

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Frequency Effects of the components

• Resistors are of constant value across the audio
  frequency range
• There is no phase shift between V and I
• Inductors and Capacitors change their reactance
  with frequency(f)
• Voltage drop across terminals changes with f
• Phase shift for L is 90 between V and I
• Phase shift for C is -90 between V and I

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Uses for Components

• Filters low pass, high pass, band pass
• Coupling AC, uncoupling DC
• Shunting power ripple (AC to ground)
• Changing Voltage or current levels

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Tone Control
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Miniamp
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Wire

• Made of a single strand or multiple strands
• Multistrand increase flexibility and reduce
  resistance

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Types of Wires
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Types of Wires
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Connectors
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Connectors

• XLR
• ¼
• RCA
• MIDI

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XLR Cable

• Industry standard
• Low impedance balanced wires
• Carries line or mircrophone level audio

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¼ Cables

• High impedance, unbalanced lines
• Used mainly from instrument to Amplifier
• Keep as short as possible
• Another type using unshielded low gauge wire are
  high power cables used for amp to speaker
  connection

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MIDI Cable

• Five pin digital info
• Common computer cable

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RCA Cable

• For amature equipment
• Lower line-level voltage

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Schematics
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Jen Fuss

• Makes the guitar sound hard, rich of treble.

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Audio Mixer
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22 Watt Audio Amplifier