Classification of transducers
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Transducers can be classified in several ways: - Active transducers generate their own power to produce an output signal proportional to the input, like piezoelectric transducers, while passive transducers require an external power source. - Primary transducers convert a physical input directly into motion, then secondary transducers convert that motion into an electrical signal. - Transducers can also be categorized by their transduction principle, such as capacitive, electromagnetic, inductive, piezoelectric, photovoltaic, and photoconductive. - Analog transducers produce a continuous output signal, versus digital transducers which produce a pulse-based 0s and 1s
Classification of transducers
- 1. Powerpoint Presentation on Classification of Transducers
- 2. Transducers • A Transducer is a device which converts one form of energy into another form. • Alternatively, a Transducer is defined as a device which provides usable output response to a specific input measured which may be a physical quantity. • A Transducer can also be defined as a device when actuated by energy in one system supplies energy in the same form or in another form to a second system.
- 3. Classification of Transducers • Transducers may be classified according to their application, method of energy conversion, nature of the output signal, and so on. • Transducers On The Basis of principle Used Active/Passive Primary/Secondary Analog/Digital Transducers/ Inverse Transducers Capacitive Inductive Resistive
- 4. Active and Passive Transducers • Active transducers : • These transducers do not need any external source of power for their operation. Therefore they are also called as self generating type transducers. I. The active transducer are self generating devices which operate under the energy conversion principle. II. As the output of active transducers we get an equivalent electrical output signal e.g. temperature or strain to electric potential, without any external source of energy being used
- 5. Classification of Active Transducers
- 6. Example of active transducers • Piezoelectric Transducer- When an external force is applied on to a quartz crystal, there will be a change in the voltage generated across the surface. This change is measured by its corresponding value of sound or vibration.
- 7. Passive Transducers • These transducers need external source of power for their operation. So they are not self generating type transducers. • A DC power supply or an audio frequency generator is used as an external power source. • These transducers produce the output signal in the form of variation in electrical parameter like resistance, capacitance or inductance. • Examples – Thermistor, Potentiometer type transducer
- 8. Primary and Secondary Transducers • Some transducers contain the mechanical as well as electrical device. The mechanical device converts the physical quantity to be measured into a mechanical signal. Such mechanical device are called as the primary transducers, because they deal with the physical quantity to be measured. • The electrical device then convert this mechanical signal into a corresponding electrical signal. Such electrical device are known as secondary transducers.
- 9. Example of Primary and secondary transducer Primary transducer Displacement voltage Secondary transducer
- 10. According to Transduction principle used
- 11. Capacitive Transduction: • Here, the measurand is converted into a change in capacitance. • A change in capacitance occurs either by changing the distance between the two plates or by changing the dielectric. d Area=A
- 12. Electromagnetic transduction: • In electromagnetic transduction, the measurand is converted to voltage induced in conductor by change in the magnetic flux, in absence of excitation. • The electromagnetic transducer are self generating active transducers • The motion between a piece of magnet and an electromagnet is responsible for the change in flux
- 13. Inductance Transduction: • In inductive transduction, the measurand is converted into a change in the self inductance of a single coil. It is achieved by displacing the core of the coil that is attached to a mechanical sensing element Piezoelectric Transduction: • In piezoelectric induction the measurand is converted into a change in electrostatic charge q or voltage V generated by crystals when it is mechanically stressed.
- 14. Photovoltaic Transduction: • In photovoltaic transduction the measurand is converted to voltage generated when the junction between dissimilar material is illuminated.
- 15. Photoconductive Transduction: • In photoconductive transduction the measurand is converted to change in resistance of semiconductor material by the change in light incident on the material.
- 16. Analog and Digital Transducers Analog transducers: • These transducers convert the input quantity into an analog output which is a continuous function of time. • Thus a strain gauge, an L.V.D.T., a thermocouple or a thermistor may be called as Analog Transducers as they give an output which is a continuous function of time. Digital Transducers: • These transducers convert the input quantity into an electrical output which is in the form of pulses and its output is represented by 0 and 1.
- 17. Transducer and Inverse Transducer Transducer: • Transducers convert non electrical quantity to electrical quantity. Inverse Transducer: • Inverse transducers convert electrical quantity to a non electrical quantity. A piezoelectric crystal acts as an inverse transducer because when a voltage is applied across its surfaces, it changes its dimensions causing a mechanical displacement.
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