Deck 17: Understanding Transducers, Sensors, and Conversion in Industrial Processes

Question 1

Displacement transducers can be made using a variety of types of optical or electrical circuits.

Answer 1

True

Question 2

One method of providing an accurate thermocouple interface is:

A)capacitive coupling.
B)to use a reference thermocouple.
C)to use a referenceVoltage in the feedback circuit.
D)to use a swamping resistor.

Answer 2

to use a reference thermocouple.

Question 3

Basic analog physical parameters such as angular position, temperature, pressure, strain, and flow rate can be measured by What devices?

A)Transmissions
B)Transducers
C)Telemeters
D)Transmitters

Answer 3

Transmitters

Question 4

Pressure sensors make use of an RTD for their operation.

Question 5

The aperture time for a sample-and-hold circuit refers to the change in the voltage from the sampled value during the hold interval time.

Question 6

What device has the same function as a thermocouple but has a more linear output?

A)resistance temperature detectors
B)analog temperature device
C)capacitive temperature detector
D)linear temperature device

Question 7

Which of the following is not a temperature sensor?

A)thermocouple
B)thermistor
C)resistance temperature detector
D)triac

Question 8

A cold-junction:

A)opposes measured temperature.
B)can have an unpredictable effect on the thermocouple effect.
C)has aValue that depends on ambient temperature.
D)all of the above.

Question 9

What device is formed by adjoining two dissimilar metals?

A)pop-sensor
B)thermocouple
C)sequencer
D)none of the above

Question 10

What affects the accurate operation of a resistance bridge measuring temperature?

A)inputVoltage
B)length of Wires going to the detector
C)ambient temperature
D)all of the above

Question 11

Conversion of analog signals to digital signals is common in most controlled industrial processes.

Question 12

A SCR is used mainly in the control of AC circuits.

Question 13

Circuits that contain features such as common-mode rejection, isolation, gain, etc. are called:

A)signal conditioners.
B)interfaces.
C)thermocouples.
D)none of the above.

Question 14

Analog-to-Digital conversion takes a specific analog quantity and produces a unique binary number to represent that quantity.

Question 15

RTDs and thermistors both operate on the same principle of resistive changeW ith temperature.

Question 16

A triac must be triggered for each alternation for proper operation.

Question 17

The typical output for a normally operating thermocouple is in the range of 1 V to 10 V.

Question 18

The ac value that is equal to the same dc heating effect is usually called:

A) peak value.
B) heat value.
C) rms value.
D) average value.

Question 19

An input transducer converts:

A)voltage to current.
B)a nonelectrical quantity to an electrical quantity.
C)current to Voltage.
D)an electrical quantity to a nonelectrical quantity.

Question 20

Strain gauges are used to detect minute changes in temperature.

Question 21

Which of the following devices changes resistance inverselyW ith the temperature?

A)thermocouple
B)thermistor
C)RTD
D)triac

Question 22

The voltage gain of an instrumentation amplifier is setW ith an external resistor.

Question 23

The deformation of a material due to force acting on it is called:

A)stress.
B)compression.
C)pressure.
D)strain.

Question 24

A basic instrumentation amplifier has three op-amps.

Question 25

Voltage storage in a sample and hold amplifier is accomplished by:

A)a JFET switch
B)a holding inductor.
C)a holding capacitor.
D)the output buffer op-amp.

Question 26

A basic isolation amplifier has two electrically isolated sections.

Question 27

Displacement transducers make use ofW hich of the following?

A)capacitance
B)magnetism
C)light
D)any of the above

Question 28

One common method of measuring flow rate of a fluid through a pipe is the:

A)differential pressure method.
B)dynaflow method.
C)wein-bridge method.
D)hall effect.

Question 29

Which of the following ADC circuits has the highest resolution?

A)16 bit
B)one that has the highest aperture time
C)4 bit
D)none of the above

Question 30

Sample and hold circuits:

A)increase resolution.
B)convert analogVoltages to a binary number.
C)reduce quantization error.
D)all of the above.

Question 31

Which of the following components is not used as a temperature measurement device?

A)thermocouple
B)RTD
C)triac
D)All are used to measure temperature changes.

Question 32

Which of the following is not a force-related parameter?

A)motion
B)strain
C)pressure
D)velocity

Question 33

A device that exhibits a change in resistance based on a change in pressure is called a:

A)gauge transducer.
B)psi gauge.
C)pressure transducer.
D)none of the above.

Question 34

Most isolation amplifiers use transformer coupling for isolation.

Question 35

Since the triac can be triggered to allow current to flow both directions, it can be used in:

A)phase control.
B)dc circuits.
C)ac circuits.
D)any of the above.

Question 36

The device often used as an electronic switch in many applications is the:

A)SCR.
B)SPDT.
C)diode.
D)SPST.

Question 37

One of the key characteristics of an instrumentation amplifier is its low input impedance.

Question 38

The quantity usually measured using a spring-supported seismic mass is:

A)velocity.
B)weight.
C)volume.
D)acceleration.

Question 39

What quantity indicates change in positions of a body or point?

A)motion coefficient
B)displacement
C)FIFO
D)relative velocity

Question 40

Precise control of a triac to prevent high-frequency transients is called:

A)microcontroller pulsing.
B)zero-voltage switching.
C)pulse switch triggering.
D)negative feedback biasing.

Question 41

(d)

Figure $20 < 1$


-Refer to Figure 20-1 (a). If $\mathrm { R } _ { 1 } = \mathrm { R } _ { 2 } = 30 \mathrm { k \Omega }$ and the closed loop gain is 450 , the value of the external gain-setting resistor $R _ { G }$ is:

A) $134 \mathrm { k } \Omega$
B) $13.4 \Omega$
C) $134 \Omega$
D) none of the above.

Question 42

An active clamping circuit negates the opposite polarity 0.7 V peak by using two diodes in series.

Question 43

Active limiting and clamping employs an amplifier circuit.

Question 44

Refer to Figure 20-2.Which of these circuits contains an OTA?

A)(a)
B)(b)
C)(c)
D)(d)

Question 45

A voltage-to-current converter has a JFET in the feedback loop.

Question 46

A voltage-to-current converterW orks by controlling current proportional to the input Voltage.

Question 47

Refer to Figure 20-1.W hich of these circuits is known as an instrumentation amplifier?

A)(a)
B)(b)
C)(c)
D)(d)

Question 48

Refer to Figure 20-1.W hich of these circuits is known as a constant-current source?

A)(a)
B)(b)
C)(c)
D)(d)

Question 49

Refer to Figure 20-1.W hich of these circuits is known as an isolation amplifier?

A)(a)
B)(b)
C)(c)
D)(d)

Question 50

A voltage limiter that limits both positive and negative peaks uses two zener diodes connected anode to cathode.

Question 51

Refer to Figure 20-2.Which of these circuits is known as a voltage-to-current converter?

A)(a)
B)(b)
C)(c)
D)(d)

Question 52

The OTA is a voltage-to-current amplifier.

Question 53

OTA stands for operational transistor amplifier.

Question 54

A peak detectorʹs output continually changes based on the input.

Question 55

Refer to Figure 20-1 (a). If and , the A_cl would be:

A) 551 .
B) 560 .
C) 56.1 .
D) 5.61 .

Question 56

Refer to Figure 20-2.Which of these circuits is known as a current-to-voltage converter?

A)(a)
B)(b)
C)(c)
D)(d)

Question 57

The main purpose of an instrumentation amplifier is to amplify common mode Voltage.

Question 58

The OTA has a ________ input impedance and a ________ CMRR.

A)low, low
B)high, low
C)low, high
D)high, high

Question 59

The diode clamper circuit output is an ac signal that has a dc reference point of the peak voltage of the ac.

Question 60

Refer to Figure 20-1 (b). If V_in =5 V and R_in=22 kΩ , the current thru the load R_L would be:

A) 227 https://d2lvgg3v3hfg70.cloudfront.net/TB34225555/.
B) 227 mA
C) 22.7 mA
D) 22.7

Question 61

An instrumentation amplifier has a high:

A)output impedance.
B)supply Voltage.
C)CMRR.
D)power gain.

Question 62

The output of a peak detector is always:

A) equal to the min value of the peak level received since the last reset pulse.
B) 70.7% of input.
C) equal to the max value of the peak level received since the last reset pulse.
D) none of the above.

Question 63

An active limiter includes an op-ampW hich:

A)works better under loaded conditions.
B)keeps the circuit from oscillating.
C)increases the output Voltage.
D)allows a reference level to be set.

Question 64

The input signal for an instrumentation amplifier usually comes from:

A)a transducer.
B)an inverting amplifier.
C)a Wheatstone bridge.
D)a differential amplifier.

Question 65

An instrumentation amp with one open input:

A) may work correctly in a low noise environment.
B) will not work at all.
C) will allow common-mode noise to be present on the output.
D) both A and C

Question 66

Refer to Figure 20-2.Which of these circuits is known as a peak detector?

A)(a)
B)(b)
C)(c)
D)(d)

Question 67

In the classic three op-amp instrumentation amplifier, the differential voltage gain is usually produced by the:

A)second stage.
B)output op amp.
C)mismatched resistors.
D)first stage.

Question 68

Which statement best differentiates between limiter and clamper circuits?

A) A limiter limits the both peaks of the output of a given signal, while the clamper limits only one.
B) A limiter sets the limit of the peak output of a given signal while the clamper establishes a dc reference level based on the peak output of the signal from which the ac signal will vary.
C) A limiter sets a dc reference voltage that the ac signal varies upon while the clamper limits the peak output.
D) none of the above

Question 69

If an operational transconductance amplifier (OTA)is used as a nonlinear mixer and an audio signal is mixedW ith an RF signal, the outputW ill be a(n)________ signal.

A)amplitude modulated (AM)
B)square Wave
C)triangular Wave
D)frequency modulated (FM)

Question 70

How many op-amps does the basic instrumentation amplifier consist of?

A)2
B)3
C)4
D)5

Question 71

Two zener diodes are used in a limiter circuit to:

A)better regulate a power supply.
B)limit both positive and negative peaks.
C)reduce interelectrode capacitance at high frequencies.
D)none of the above

Question 72

The voltage gain of an OTA can be calculated using the formula:

A)
B)
C)
D)

Question 73

When using an OTA in a Schmitt-trigger configuration, the trigger points are controlled by:

A)the IOUT.
B)the IBIAS.
C)theV OUT.
D)both A and B.

Question 74

Which op-amp circuitW ould be useful to switch to an ʺonʺ condition at a specified voltage?

A)instrumentation amp
B)isolation amplifier
C)operational transconductance amplifier configured as a Schmitt-trigger
D)voltage-to-current converter

Question 75

Refer to Figure 20-2 (d). If gm=25 mS and
, the voltage gain would be:

A) 62.5 .
B) 625 .
C) 6.25 .
D) not enough information.

Question 76

The primary function of the oscillator in an isolation amplifier is to:

A)convert dc to low frequency ac.
B)rectify high frequency ac to dc.
C)convert dc to high frequency ac.
D)produce dual polarity dcVoltages for the input to the demodulator.

Question 77

Refer to Figure 20-2 (b). If R_L=20 k, R₁=1.2 k , and V_in=2.5 V , the load current I_L would be:

A) 2.08 mA .
B) 2.08 A .
C) 208 A .
D) 20.8 mA.

Question 78

In some respects an isolation amplifier is nothing more than an elaborate:

A)instrumentation amplifier.
B)op amp.
C)rectifier and filter.
D)both A and B

Question 79

A voltage-to-current converter is used in applicationsW here itʹs necessary to have an output load current that is controlled by ________.

A)inputVoltage
B)input frequency
C)output resistance
D)input resistance

Question 80

Which statement best describes the action of an OTA amplitude modulator?

A) The power supply bias adjusts the output level.
B) Variations of light intensity adjust the gain of the amplifier.
C) The variations of voltages applied to the current bias input adjusts the gain of the amplifier.
D) The OTA is versatile and can be configured to work in any of these ways.