ELECTROTECHNOLOGY III

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ELECTROTECHNOLOGY III

• Farah Khalid
• REVIEW I

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TOPIC COVERED for the CLASS TEST I

• Real Time Systems
• Conditioning Circuits
• Wheatstone Bridge
• Amplifiers
• Transducers
• Temperature Transducers
• Light Transducers

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Real Time Systems

• Process Variable
• Process State
• Sensors (includes the transducer and the
  conditioning circuit)
• ADCs
• Microprocessor/Computer
• DACs
• Actuators

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Modelling of the real time system

• Ht(x) Transducer function
• varies, depends on the type of transducer used.
• Hc(v) Av Conditioning Circuit function
  (Amplifier, where v is the input voltage)
• The input to the amplifier can be either voltage
  or current
• HADC(hb)(v) v (2b 1)/h ADC function
  (where h is a voltage and b is an integer)
• convert voltages in the range 0 to h (inclusive)
  to a binary number from 0 to 2b-1
• Input to the Computer HADC(hb) (Hc (Ht(x)))

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Wheatstone Bridge

• What is it used for?
• Modes of operation
• Null deflection method ( As was done in the lab)
• Unbalanced condition
• When used in the balanced condition
• In the Unbalanced condition
• NOTE Formula only applies to case where all
  resistances in the bridge are equal when the
  bridge is balanced.

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AMPLIFIERS

• Characteristics of an Ideal amplifiers
• Golden Rules of an Amplifier
• Input, Output, Dynamic and other parameters
• Open Loop Amplifier
• Use of negative feedback
• Modes of Operation, calculation of Gain
• Inverting
• Non-inverting
• Voltage follower
• Differential
• Integrator
• Differentiator
• Instrumentation Amplifier

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TRANSDUCERS

• What is a transducer?
• Types of transducers
• Modelling of a transducer
• Mathematic representation of the transducer
• Symbol Ht denotes the function.
• Let x be a process variable.
• Then Ht(x) is the output of the transducer with
  function Ht.
• x can be change in temperature, resistance,
  light energy etc.

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TEMPERATURE TRANSDUCER

• Types
• Thermister Changes in resistance of a
  semiconductor material
• RTD Changes in resistance of a metal
• Thermocouple Current generated when two
  dissimilar metals are fused at 2 ends and one
  junction is heated.
• Temperature range
• Principle of operation
• Desirable/undesirable characteristics
• Thermoelectric Effects
• Seebeck effect
• Peltier Effect
• Faraday Effect
• Problems?

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LIGHT TRANSDUCER

• Process variable Light Energy or Radiant Flux
• Types
• Photodiode
• Phototransistor
• Light Emitting Diode
• Principle of Operation
• Desirable/Undesirable characteristics
• Problems?