TRANSDUCER INTRODUCTION AND TYPES OF TRANSDUCERS.pptx

This power point explains about transducers and its types

1. TRANSDUCER

2. Transducer A device which converts the physical quantity into the proportional electrical signal is called as transducer. Active and Passive Transducer Active Transducer Active transducers self generating type transducers. Develop an electrical parameter which is proportional to the quantity under measurement. It do not require any external power for their operations

3. Types Photovoltaic Transducer Thermo electric transducer Piezoelectric transducer Electromagnetic transducer Passive transducer Passive transducers do not generate any electrical signal by themselves. An external power source is required. It depends upon the change in electrical parameters They are known as externally power driven transducers.

4. Capacitive Transduction In this type, measurand is converted into change in capacitance. A capacitor is basically consists of two conductors separated by an insulator. A change in capacitance can be occur by changing the distance between the two plates or by chan ge in the dielectric.

5. Electromagnetic transduction In this, the measurand is converted into the electromotive force induced in a conductor by changing the magnetic flux, in the absence of the excitation. They are self generating active type transducers. The relative motion between the magnet or a piece of magnet material and an electromagnet brings out the change in magnetic flux.

6. Inductive transduction In this, the measurand is converted into the change in the self inductance of the single coil. This is accomplished by displacing the coil’s core, which is linked or attached to a mechanical sensing element.

7. Piezoelectric Transduction In Piezoelectric Transduction, measurand is converted into change in electrostatic charge, q or voltage, V generated by the crystals when mechanically stressed.

8. Photovoltaic and Photoconductive Transduction In Photovoltaic Transduction, the measurand is converted in the voltage generated when the junction between dissimilar material is illuminated. In Photoinductive Transduction, the measurand is conveyed into the change in resistance of a semiconductor material by a change in the amount of illumination incident on the material.

9. Analog and Digital transducers The transducers can be classified on the basis of the output which may be a continuous function of time or the output may be in discrete steps. Analog Transducer These transducers convert the input quantity into an analog output which is a continuous function of time. A strain gauge, LVDT, thermocouples or thermistors are called analog transducers as they produce an output which is a continuous function of time. Digital Transducers Digital transducers produce an electrical output in the form of pulses which forms an unique code. Unique code is generated for each discrete value sensed.

10. Primary or Secondary Some transducers consist of mechanical device along with the electrical device. In such transducers mechanical device acts as a primary transducer and converts physical quantity into mechanical signal. The electrical device then converts mechanical signal produced by primary transducer into an electrical signal. Therefore, electrical device acts as a secondary transducer. For an example, in pressure measurement Bourdon's tube acts as a primary transducer which converts a pressure into displacement and LVDT acts as a secondary transducer which converts this displacement into an equivalent electrical signal.

11. Transducer and Inverse Transducer Transducer convert non-electrical quantity into the electrical quantity whereas inverse transducer electrical quantity into non-electrical quantity. For example, microphone is a transducer which converts sound signal to electrical signal whereas loud speaker is an inverse transducer which converts electrical signal into sound signal.

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