Amplifier Applications

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Amplifier Applications

• CEC

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Contents

• Block Level Treatment of a
• Public Address System.
• Public Address System with Equaliser.
• Instrumentation System.

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Public Address System

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Contents

• Introduction and Block Schematics.
• Public Address System.
• Public Address System with Equaliser.
• Applications.

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Public Address System

• An electronic system comprising of microphones,
  amplifiers loudspeakers, and related equipment.
• Increases the apparent volume (loudness) of a
  human voice, musical instrument, or other
  acoustic sound source or recorded sound or music.

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Public Address System
Sound Signals
Sound
Sound is reproduced faithfully when loud speaker
reproduces the sound signals from the microphone
sufficiently loud without noise.
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Public Address System

• Sound source at the input side of public address
  system.
• Microphone converts speech/sound energy to
  electrical energy.
• Output from microphone will be of very low
  amplitudes (of the order of µV).
• Microphone output to be amplified in terms of
  voltage and power.

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Public Address System

• Mixer multiplexes/combines several channels, ie
  outputs of several microphones.
• Mixer needed if instruments and vocal are to be
  combined.
• Preamplifier increases input amplitude for
  further processing.

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Public Address System

• Power amplifier boosts current, makes signal
  strong enough to drive the loudspeaker.
• Loudspeaker converts electrical energy back to
  sound energy.
• Loudspeaker to reproduce sound faithfully.

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PA System with Equaliser

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Equalization

• Process of altering the frequency response of a
  PA System using filters.
• Adjusts the magnitude of audio signals at
  selected frequencies.
• Used to eliminate undesired sounds.
• To make some voices more prominent.

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Equalization

• Graphic equalizer permits the operator to see
  graphically and control different frequency
  bands.
• Graphic equalizer separates low frequency (bass)
  and high frequency (treble) signals.
• Bass and Treble amplified and reproduced using
  separate loud speakers.

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PA Applications

• Live Music Concerts.
• Public Speech Scenarios.
• Replay of pre-recorded music/speech.
• Announcement System at a school, office or
  outdoor gathering/function.
• Announcement Systems in Public Places,
  Auditoriums and Stadiums.
• Public Warning/Announcement.

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Instrumentation System

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Contents

• Definition and Block Diagram.
• Sensing/Transduction.
• Types of Transducers.
• Signal Conditioning.
• Transmission and Presentation.
• Advanced Instrumentation.
• Applications.

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Instrumentation

• Branch of engineering/technology dealing with
  instruments.
• Deals with instruments to record, monitor,
  indicate and control various physical parameters
  such as pressure, temperature etc.

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Basic Block Diagram

Conversion to Electrical Quantity
Amplification/Processing
Physical Quantity
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Generalised Block Diagram of an Instrumentation
System

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Primary Sensing Element

• Also known as sensor.
• Transducers used as primary sensing elements.
• Physical quantity (temperature, pressure etc.)
  sensed, converted into analog signal.
• Output of transducer an electrical signal i.e.
  voltage, current etc.

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Sensor vs Transducer

• Transducer to convert a non-electrical signal
  into an electrical signal.
• Sensor to measure physical changes in the
  surroundings like temperature, light, etc, for
  conversion to a readable signal.
• Sensors barometer, accelerometer.
• Transducers thermocouple, microphones.
• Transducer consists of a sensor and signals
  conditioning circuits.

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Transducer Classifications

• Primary transducer, detector or sensor senses a
  physical parameter (pressure, humidity,
  temperature etc.), converts it into readable
  physical parameter.
• Secondary transducer converts the output of
  primary transducer into electrical signal.
• Eg Bourdons Tube converts pressure into a
  displacement, LVDT converts it into a voltage.

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Transducer Classifications

• Active transducer self generating, no external
  power supply to produce output. Eg Thermocouple,
  Photovoltaic Cell.
• Passive transducer - externally powered,
  auxiliary power supply to produce output. Eg
  Capacitive, Resistive and Inductive transducers.
• Analog transducer - converts input signal into
  analog output. Eg Strain Gauge, LVDT.
• Digital transducer - converts input signal into
  electrical pulses.

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Transducer Classifications

• Electrical transducers - sense physical
  parameter, converts it into electrical signal.
• Mechanical transducers - convert one form of
  physical quantity into another form of physical
  quantity.
• Optical transducers - convert light into
  electrical quantity, also called photoelectric
  transducers.

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Inverse Transducer

• Converts the electric quantity into a physical
  quantity.
• High electrical input and low non-electrical
  output.
• Eg Piezoelectric Crystal - voltage across the
  surface of a piezoelectric crystal changes its
  dimension.

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Variable Conversion Element

• Converts the output of primary sensing element
  into a suitable form without changing
  information.
• Secondary transducers may perform the conversion.

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Variable Manipulation Element

• Manipulation - change in numerical value of
  signal.
• To convert the signal into suitable range.

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Data Transmission Element

• For measurement and control from a distance.
• Data transmitted from one place to another place
  through a channel.
• Transmission path are pneumatic pipe, electrical
  cable and radio links.
• Telemetry system uses radio link.

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Data Presentation or Controlling Element

• Output is recorded or given to the controller to
  perform action.
• Performs different functions like indicating,
  recording or controlling.
• Can be a display panel/panel meter.

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Digital Instrumentation System

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Smart Instrumentation and Telemetry

Computer controlled Smart Instrumentation uses
smart sensors and smart instruments which can be
interfaced to the computer or microcontroller
through serial/parallel ports.
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Applications

• In Process Control Industries (Chemical and
  Fertilizer Plants) to measure and control
  parameters such as pressure, temperature etc.
• In test stands during testing stages of
  propulsion systems and rockets to measure and
  control various parameters from a distance.
• In Thermal and Nuclear Power Plants.

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References

• Your prescribed text books.
• K A Nawas and T A Suhail, Basics of Electronics
  Engineering, Rajath Publishers, 2nd Edition,
  2016.
• https//www.polytechnichub.com
• https//circuitglobe.com/types-of-transducer.html
• https//www.stechies.com/difference-between-sensor
  -transducer/
• Other Internet Resources.

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• Thank You..