Date post: | 19-Jul-2015 |
Category: |
Engineering |
Upload: | sudhakar-kumar |
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Raj Kamal [2012EEC01]
Sudhakar Kumar [2012EEC02]
Abhishek Chauhan [2012EEC03]
Shubham Kumar Pandey [2012EEC04]
What is a transducer?• A device, which when actuated by energy in one
transmission system, supplies energy in the sameform or in another form to a second transmissionsystem.
• The non-electrical quantity is converted into anelectrical signal.
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
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.
Selecting a Transducer Operating Range
Frequency Response and Resonant Frequency
Environmental Capability
Minimum Sensitivity and Sensitivity
Accuracy
Usage and Ruggedness
Electrical Parameters
Combating Noise To increase the strength of low level signals before
transmission through the wires.
Done with the help of an Instrumentation Amplifier.
Instrumentation Amplifier Finite gain
High impedance
differential input
High Common-mode
voltage range
High Common-mode
rejection (90 dB)
Noise Effect The connections to the transducer should be
differential to prevent the introduction the noise.
Use of Isolation Amplifiers where the noiseenvironment is so severe that conventional amplifierscan’t survive the signal levels encountered.
Sources of Error These errors occur when transmitting a low-level
signal to any significant distance.
A method of reducing errors due to interveningresistances and the effect of power supply currents is touse current rather than voltages for transmission.
Voltage-to-Frequency Converter An Integrator that feeds a comparator, which in turn
drives a one-shot multivibrator. An electronic switchdischarges the integrator via a current source.
The major reason for converting a voltage to afrequency is so that an analog signal can betransmitted through a communication system,whether it be wires or some more sophisticatedsystem.