A transducer is a device that converts one form of energy into another. There are two main types: active transducers that generate electrical signals without an external power source, and passive transducers that require an external power source. Transducers can operate via different mechanisms including capacitive, electromagnetic, inductive, piezoelectric, photovoltaic, and photoconductive transduction. Transducers can also be classified as analog if they produce continuous outputs or digital if they produce pulse-coded outputs. Some transducers have both a primary component that converts the physical input into motion and a secondary component that converts the motion into an electrical signal. A transducer differs from an inverse transducer in that a

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.

5. 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 change in the dielectric.

6. 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.

7. 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.

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

9. 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.

10. 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.

11. 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.

13. 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.

14. THANK YOU