GATE for Instrumentation

Transducer: Signal Conditioning Circuit Table Transducer Book   Sr. No Transducer Signal Condition Circuit 1 Strain Gauge DC Bridge (Wheatstone bridge) 2 LVDT (Linear Variable Differential Transformer) Phase Sensitive Detector 3 RTD DC Bridge (Wheatstone bridge) 4 Piezoelectric Transducer Charge Amplifier 5 Thermocouple Cold Junction Compensation 6 Capacitance Transducer Push-Pull configuration, Capacitance Amplifier 7 PH Transducer Amplifier with High Input Impedance 8 LDR (light Dependence Resistance) Amplifier 9 Thermistor Bridge amplifier

1. Temperature Measurement https://youtu.be/As5kzxkyT24 http://nptel.ac.in/courses/108105063/4 https://youtu.be/5_MpULxwijg https://youtu.be/8nVnsKNR6dI https://youtu.be/85gm5aqeY44 https://youtu.be/ksJYAt9YupY 2. Pressure, Force and Torque Sensors https://youtu.be/0MP_9n08urA4 http://nptel.ac.in/courses/108105063/5 https://youtu.be/ydyVsVk96z8 https://youtu.be/9VpimWrPTaM https://youtu.be/RARjXXaFEQ0 3. Flow Measurement https://youtu.be/gByrUkZUnKo http://nptel.ac.in/courses/108105063/7 4. Level, Humidity, Viscosity and pH Measurement http://nptel.ac.in/courses/108105063/8 https://youtu.be/aM6ASRHwh8k 5.Strain Gauge https://youtu.be/lUjBmV4wMtA 6. LVDT https://youtu.be/g5OOzVcgfUQ 7. Capacitance Transducers https://youtu.be/f6miNLVGTqU 8. Piezoelectric Transducers https://youtu.be/QaNDC44ADHY

Piezoelectric Sensor Piezoelectric Transducer   It is example of active and passive transducer.  Piezo-electric effect Direct Effect: generating an electric charge when subjecting it to a strain Indirect Effect: Generating a mechanical strain in response to an applied electric field   Piezoelectric Material:  Natural :  Tourmaline; Quartz; Topaz; Rochelle salt  Synthetic: Barium Titanate (BaTiO 3 ); Lead Zirconate (PbZio 3 ); Polymer Films (Polyvinylidene fluoride (PVDF), (-CH2-CF2-)n). Applications:  Mechanical variables such as pressure, force and acceleration.  Gas Lighters Quartz clocks Loudspeaker Signal Conditioning Circuit: Charge Amplifier  Formula for piezoelectric transducer 

Sr. No Variable Sensor Remark 1 Temperature RTD(Resistance Temperature detector / Resistance Thermometer As temp. increase resistance increase. (mostly linear) Thermocouple (Two metals connected together) Active Transducer, generate voltage depends on temp. difference and material used. Thermistor NTC (Negative temperature coefficient), As temp. increase resistance decrease. Non linear Pyrometer Used for high temperature measurement LM 35 (Semiconductor IC) Most linear Temp. sensor Bimetallic Thermometer Two metal connected with different temperature coefficient 2 Flow Variable area flow meter ( rotameter )   Linear Scale, Float position change with flow, Q α h ...

   1. Passive Transducer:  No generation of voltage Eg. , Strain Gauge, RTD  (Resistance Temperature Detector),  Resistance Hygrometer, Thermistor,   Piezoelectric Transducer,  etc.  2. Active Transducer: Generation of voltage/current E.g.  Thermocouple, Piezoelectric Transducer, Photo-volatile Cell, Tachogenerator  3. Analog Transducer  E.g., Strain Gauge, LVDT, Thermocouple, Thermistor 4. Digital Transducer E.g.,  Tu rbine meter used in for flow measurement 5. Transducer (converts a non-electrical quantity into an electrical quantity) Eg. LVDT (mechanical displacement to electrical), Thermocouple (Temp to voltage) 6. Inverse Transducer (an electrical quantity into a non-electrical quantity) E.g., Piezoelectric crystals  7. Primary and secondary Transducer  E.g. For pressure measurement, a bourden tube is used, which is used to convert pressure to displacement. After, LVDT ...