segi transducer

8/10/2019 Segi Transducer

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TRANSDUCER


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TRANSDUCER

Convert variousphysical

quantities intorelated

electrical values

Any device thatconvert oneenergy to

another

In electronic

instrumentationnonelectrical

physicalquantity

electrical signal


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WHY WE NEED

TRANSDUCERS?


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TRANSDUCERS

INDAILY LIFE


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Transducers

inyour daily life


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How does microphone works

Sound waves hit the diaphragm, itcauses the diaphragm to vibrate.

Coils within the magnetic field insidethe microphone starts to vibrates.

Current is generated.

When coil is shorted

current startsto flow in the coil.

Convert sound electrical energy.


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TRANSDUCER FUNCTION

Sense thepresence,

magnitude, changein, and frequency

of some*measurand

Sense

Provide anelectrical output

that givesaccurate

quantitative dataabout *mesurand

Provideoutput

Transducer

MeasurandElectrical

Output

Excitation

Transducers block diagram

*Measurand =

the quantity,property, or

conditiontranslated intoelectrical signal


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TYPES OF TRANSDUCERS

Passive Active/Self Generating

Transducers- Variable resistance

- Variable inductance

- Variable capacitance

- Moving-coil generator

- Thermocouple

- Piezoelectric

- Photovoltaic cell


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HOW TO SELECT ATRANSDUCER?


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ASCERTAIN ON THE FOLLOWINGCRITERIA

Operating range range requirement & goodresolutions

Sensitivity to allow sufficient output

Accuracy to minimize calibration error

Environmental compatibility ensure that theimpact from the environment (i.e. humidity,

extreme hot or cold etc.) does notcompromise the transducer used

Electrical determine the additionalappliances needed


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COMMON TRANSDUCERS

Resistive positiontransducers

Strain gauge

Capacitive transducers

Variable inductancetransducers

Piezoelectrictransducers

Resistancetemperature detectors

Thermocouples

Thermistors

Photoconductive cells

Photodiode

Phototransistor


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Resistive position transducers

VT

R

R

V

Principle the physical variable undermeasurement that causes resistance change in

the sensing element

Basic equations

A

B


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Exercise example:

A displacement transducer with a shaft stroke of 3.0 in.is applied in the circuit of the previous figure. The total

resistance of the potentiometer is 5k, and the appliedvoltage VT = 5.0V. When the wiper is 0.9 in. from B, whatis the value of the output voltage V?


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Resistive position transducersExercise example:

A resistive position transducer with a resistance of 5000and a shaft strokeof 5.0 in. is used in the arrangement of figure below. Potentiometer RRis also5000and VT = 5.0 V. The initial position to be used as a reference point issuch that R= R(i.e. the shaft is at midstroke). At the start of the test,potentiometer RRis adjusted so that the bridge is balanced (V= 0).Assuming that the object being monitored will move a maximum distance of 0.5in. toward A, what will the new value of Vbe? (If the wiper moves 0.5 in.toward A from midstroke, it will be 3.0 in. from B).

R

R

x

VT

VE


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To be continued in the next

lecture

segi transducer

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