The various types of transducers, along with their selectivity parameters have been discussed. Also the instrumentation amplifiers and their needs have been analyzed.

1. Interfacing Transducers to
Electronic Control and
Measuring Systems

2. Raj Kamal [2012EEC01]
Sudhakar Kumar [2012EEC02]
Abhishek Chauhan [2012EEC03]
Shubham Kumar Pandey [2012EEC04]

3. What is a transducer?
• A device, which when actuated by energy in one
transmission system, supplies energy in the same
form or in another form to a second transmission
system.
• The non-electrical quantity is converted into an
electrical signal.

4. Parameters
 Linearity
 Sensitivity
 Dynamic Range
 Repeatability
 Physical Size

5. Classification of Transducers
 Basis of Application
 Potentiometric Device (Pressure,
Displacement).
 Methods of Energy Conversion
 Hall Effect Pick Up, Ionization Chamber.
 Nature of the Output Signal

6. Need of Interfacing Transducers
 Output voltages and currents from many transducers
are very small signals.
 The transducer output is needed to be transmitted
upto some distance.
 Electrical Noise can pose problems.

7. Selecting a Transducer
 Operating Range
 Frequency Response and Resonant Frequency
 Environmental Capability
 Minimum Sensitivity and Sensitivity
 Accuracy
 Usage and Ruggedness
 Electrical Parameters

8. Combating Noise
 To increase the strength of low level signals before
transmission through the wires.
 Done with the help of an Instrumentation Amplifier.

9. Instrumentation Amplifier
 Finite gain
 High impedance
differential input
 High Common-mode
voltage range
 High Common-mode
rejection (90 dB)

10. Noise Effect
 The connections to the transducer should be
differential to prevent the introduction the noise.
 Use of Isolation Amplifiers where the noise
environment is so severe that conventional amplifiers
can’t survive the signal levels encountered.

11. Sources of Error
 These errors occur when transmitting a low-level
signal to any significant distance.
 A method of reducing errors due to intervening
resistances and the effect of power supply currents is to
use current rather than voltages for transmission.

12. Voltage-to-Frequency Converter
 An Integrator that feeds a comparator, which in turn
drives a one-shot multivibrator. An electronic switch
discharges the integrator via a current source.
 The major reason for converting a voltage to a
frequency is so that an analog signal can be
transmitted through a communication system,
whether it be wires or some more sophisticated
system.

13. IEEE Standards
 IEEE 1451 is a set of smart transducer interface
standards for connecting transducers (sensors or
actuators) to microprocessors, instrumentation
systems, and control/field networks.