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I&M LAB LAB MANUAL

Name: Qasim Ali Roll No# 18143122-022 Lab Instructor: Waqas Jabar 1

Instrumentations & Measurement Lab (EE-245) List of Experiments Experiment Week No. 1

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 Introduction to Instrumentation and Measurements Trainer List the basic components of Instrumentation and Measurements Trainer and explain their function.  Positional Resistance Transducers  Plot the Variation of Output voltage with control Setting of Rotary Potentiometer  Plot the Variation of Output voltage with control Setting of Slide Potentiometer  Plot the Variation of Loading on the Potentiometer Output Voltage  Compare the application of a carbon track variable resistor to the wire wound type.

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Wheatstone bridge Measurements  Set the offset control of null detector  Measure the unknown resistance by using two unknown resistances and one variable resistance at balance. Then verify this unknown resistance with the theoretical calculated value.  Measure unknown voltage by using Wheatstone bridge  Measure unknown voltage by using Dial reading at balance and standard voltage

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Light Sensors  Observe and calculate lamp filament power and resistance  Plot the graph of photovoltaic cell, phototransistor, photoconductive cell and PIN diode against applied filament voltages. Linear Position or force Applications  Plot the graph of output voltage from the analog meter readings against core positions of a Linear Variable Differential Transformer (LVDT).  Plot the graph of output voltage against different turns of Linear Variable Capacitor.  Analyze the construction and characteristics of a strain gauge.

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Environmental Measurements

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 Analyze the construction, working and characteristics of an air flow transducer, air pressure transducer and humidity transducer.  Rotation Speed or Position Measurement.  Analyze the construction, principles and application of Slotted Opto Transducers for counting and speed measurement.  Analyze the construction, principles and application of Reflective Opto Transducers and Gray Coded Disc for position measurement.  Analyze the construction, principles and application of Inductive Transducers, Hall Effect Transducers for speed measurement.

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Sound Measurements  Analyze the construction and characteristics of a dynamic microphone, ultrasonic receiver and transmitter...

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Sound Output  Analyze the construction and characteristics of a moving coil loud speaker and buzzer.

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Linear or Rotation Motion  Analyze the construction and working of a DC Solenoid, DC relay, DC Solenoid air valve and DC permanent magnet motor.

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13

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14

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Display Devices  Analyze the characteristics and application of the Counter/Timer, State and calculate the requirement to extend the voltage range of a Moving Coil Meter.  Select a suitable device for a particular voltage measurement. Signal Conditioning Amplifiers  Analyze the characteristics and application of DC amplifiers.  Observe the use of "Offset" and the need for offset control.  Analyze the characteristics and application of an AC amplifier, power amplifier, current amplifier, buffer amplifier, inverter amplifier and differential amplifier. Signal Conversions  Plot and analyze the characteristics of a voltage to current and Current to voltage converter  Plot and analyze the characteristics of a voltage to frequency and frequency to voltage converter  Characteristics analysis of a full wave rectifier. Comparators, Oscillators and Filters  Observe the characteristics of a comparator.  The effect of hysteresis on the operation of a comparator.  Analyze the characteristics of an alarm oscillator.  Use of "latch" applied to an alarm oscillator.  Analyze the characteristics of an electronic switch, 40 kHz oscillator, band pass filters and low pass filters. Mathematical Operations  Plot the characteristics of a summing amplifier, integrator and differentiator  Analyze the characteristics and application of a "sample and hold" circuit.

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I To V and V to I converter  Observe the current to Voltage conversion and vice versa.

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Opend Handed Lab  Observe the working of schering and maxwell briges.

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Experiment # 1 Title: Introduction Instrumentation and Measurements Trainer Objectives: List the basic components of Instrument at ion and Measurements Trainer and their function. Apparatus required: DI G I AC 17 50 Transducer and Instrumentation Trainer. 

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Introduction: The digiac 1750 (D1750) unit is a comprehensive transducer and instrumentation trainer with examples of a full range of input and output transducers, signal conditioning circuits and display devices.

1-Basic control systems equipment: Open loop System: In an open loop system, a reference input, or command signal, is fed to an actuator which operates on the controlled variable to produce an output. The output magnitude depends on the magnitude of the reference input signal but the actual output magnitude for a particular input may not remain constant but may vary due to changes within or exterior to the system. Closed Loop System: In this system, the output magnitude is sensed, fed back and compared with the desired value as represented by the reference input. Any error signal is fed to the actuator to vary the controlled variable to reduce this error. The system thus tends to maintain a constant output magnitude for a fixed magnitude input reference signal. The feedback signal is effectively subtracted from the reference signal input to obtain the error signal and hence the system is referred to as a negative feedback system.

2-Input Transducers: Resistance Transducers: The unit consists basically of a "track" having a fixed resistance and a variable contact which can be moved along and make continuous contact with the track. With a voltage applied across the ends of the fixed track, a variable voltage can be obtained from the variable contact as it is moved along the track. On Digiac 1750, in addition to carbon track and wire-wound track resistance transducers, a further rotational resistance transducer is fitted to the motorised shaft assembly. Transducers for Temperature Measurement: On digiac 1750 the active transducers are contained within a clear plastic container which includes as a heater. In this unit following equipment’s are used to measure temperature. 5

1. The I.C. Temperature Transducer. 2. The Platinum R.T.D. (resistance temperature dependent). 3. The N.T.C. (negative temperature coefficient) Thermistor. 4. The Type "K" Thermocouple Temperature Transducer. Transducers for Light Measurement: The transducers are contained within a clear circular container and are illuminated by a lamp which is placed centrally. In this unit following equipment’s are used for light measurements. 1. The Photovoltaic Cell. 2. The Phototransistor. 3. The Photoconductive Cell. 4. The P.I.N. Photodiode. Transducers for Linear Position or Force: An LVDT is consisting of three coils mounted on a common former and having a magnetic core that is movable within the coils. In this transducer movement of core from its central position produces an output voltage. Strain gauge consist of a grid wire which gives variation in length under loaded conditions. Transducer for environmental measurements: Following transducer are used for Environmental measurements: 1. The air flow transducer 2. The air pressure transducer 3. The humidity transducer Transducer for sound measurements: Following transducer are used for sound measurements: 1. The dynamic microphone 2. The ultra-sonic receiver. Transducer for rotational speed or position measurements: Following transducer are used for rotational speed or position measurements: 1. Slotted opto transducer

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2. Reflected opto transducer 3. Inductive transducer 3-Output Transducers: Transducers for sound output: Following elements are used for sound output: 1. The moving coil load speaker 2. The ultra-sonic transmitter 3. The buzzer. Transducer for linear or angular motion: Following elements are used for linear and angular motion: 1. The DC solenoid 2. The DC relays. 3. The solenoid air valve 4. The DC permanent magnet motor 4-Display Devices: Following element are used as display devices: 1. The timer/ Counter 2. The L.E.D bargraph 3. The moving coil meter. 5-Signal Conditioning Circuits: These circuits are used to strengthen the week signals or transform from one form to another. On DIGIAC 1750 Following elements are used as signal conditioning circuits: 1. Amplifiers. 2. Signal convertors. 3. Comparators. 4. Oscillator& Filters. 5. Mathematical operations circuits.

The unit is self-contained and enable the characteristics of individual devices. The only recommended items are oscilloscope and digital multimeter in addition. 7

Experiment No 2 Title: Positional Resistance Transducers Objectives:     

Plot the Variation of Output voltage with control Setting of Rotary Potentiometer Plot the Variation of Output voltage with control Setting of Slide Potentiometer Plot the Variation of Loading on the Potentiometer Output Voltage Compare the application of a carbon track variable resistor to the wire wound type. Plot the Variation of Output voltage with Servo Potentiometer

Apparatus required:   

DIGIAC 1 7 5 0 Transducer a n d instrumentation Trainer. 4 m m Connecting leads. Digital Multi meter.

Procedure: 2.1- Practical Exercise Plot the Variation of Output voltage with control Setting of Rotary Potentiometer

    Control Setting Output Voltage

I Connected the circuit as shown in Fig using the power supply facilities at the bot t om of the panel and the 2 0V D C r ang e of a digital multimeter. Set the 10 0kΩ rotary resistor control full y counter - clockwise to set ting 1 as shown in Fig. Note that the dial is not marked with numbers on the print e d pane l. After ensuring that the volt ag e adjustment is correct l y s et, I switched ON the power supply. I noted down the output voltage as indicated on the digital multimeter and recorded them in T able. 1 0V

   

2

3

4

5

6

7

0.72V

2.42V

4.08V

5.46V

6.87V

8.34V

8

9

10

9.41V 11.23V 11.97V

I Set the rotary control to “2” and repeated the readings, recorded the result in table again. I Repeated the reading and recording for all other settings of the rotary control. From the results I recorded in Table above plotted the characteristic of the 100kΩ 8

variable resistor on graticule of Graph. Note: that it is not easy to be precise with your setting of the variable resistor and this may result in the plot ted points not following a smooth relationship. You should draw the best compromise to show the characteristic as you believe that it should be. At the ends of the t rack the wiper comes into contact with the terminal connect ions to the track, causing nonlinearity at both ends. From setting 2 through setting 9 the variation of voltage should be fairly linear. Voltage across this section (V9 – V2) = 10.7 V Voltage per division (V 9 – V 2 /9 - 2) = 1.5 V Enter your Voltage per Division=1.5

Obj ect3

Conclusion: Hence we can concluded that voltage drop due to increase in resistance.

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2.2- Practical Exercise Plot the Variation of Output voltage with control Setting of Slide Potentiometer

    Control Setting Output Voltage

I Connected the circuit as shown in Fig using the power supp l y facilities at the bot t om of the panel and gave 2 0V D C r ang e to digital multimeter. I Set the l 0kΩ s l ide resistor control t o t h e left to set ting 1 as shown in Fig Note that the mar k ed number s are ag a in not on the print e d panel. I Switched ON the power supp l y. Noted the output volt ag e as indicated on the dig it a l multimeter and recorded in T able. 1

2

3

4

5

-5.02V -4.17V -3.14V -1.93V -0.78V

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7

8

9

0.51V

1.79V

2.79V

4.15V

10 5V

I Set the control to "2" and repeated the reading. I Repeated the readings for all other settings of the slide control, recorded the result in Table.  From the result I recorded in Table plotted the characteristic of the 10kΩ slide resistor with dual polarity supply on graticule of Graph  I Switched OFF the power supply and removed the connect ions between the slide potentiometer and the power supply panels.  I Used the digital multimeter on a suitable range (20kΩ) to measure the resistance between terminal A and wiper B with the wiper set to position 9: Resistance R9 = 9.6 k  

Move the wiper to position 2 and repeat the resistance measurement: Resistance R2 = 1.76 kΩ Resistance between settings 9 & 2 = R9 - R2 = 7.84 kΩ Voltage between settings 9 & 2 = V9 - V2 = 8.34V Voltage Per kΩ = 1.01 V/kΩ Enter your Voltage per kΩ= 1.01 V/kΩ 10

Obj ect5

Conclusion: Hence we can concluded that voltage changes due to change in resistance.

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2.3 - Practical Exercise Plot the Variation of Loading on the Potentiometer Output Voltage Compare the application of a carbon track variable resistor to the wire wound type. 

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With the power supply switched OFF and no connect ions made to any components, I measured the resistance of the 100kΩ rotary variable resistor between contact A and the wiper as it is set to the marked points on its scale. Used a suitable scale ( 200kΩ) on digital multimeter and recorded the results in Table over leaf in the row marked "Load Resistance". The 100kΩ resistor is used as a load resistance across the output of a 10kΩ position sensing variable resistor. Connected the circuit as shown in Fig but initially leave out the lead from contact C of the 100kΩ resistor to contact B of the 10kΩ so that the load is not connected across the output. 

S witched on t h e power supply ON and adjusted t h e 10k Ω rotary r es is t or to give a n output of 6V. Do not re-adjust this setting during the rest of this exercise. 

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I Set the 10 0k Ω resistor fully clockwise (1 0) and connected the missing lead fr om cont act C of the 100kΩ resistor to cont act B of the 10k Ω so that the load i s connect ed across the output of the positional sensor (10kΩ resistor). Noted t h e output voltage and recorded i n T ab le.

Control Setting

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Output Voltage

5.8V

9

8

7

6

5.79V

5.76V

5.71V

5.66V

Load Resistance 3.86kΩ 3.85kΩ 3.80kΩ

3.78kΩ

3.74kΩ

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2

1

4.45V

1.32V

3.70kΩ 3.60kΩ 3.35kΩ 2.07kΩ

0.7kΩ

5.6V

4 5.54V

3 5.5V

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Changed the setting of the 100kΩ load resistor and recorded the effect as the load resistor is set to each marked position in Table. From the information in Table, plotted the characteristic of Output Voltage against Load Resistance on the graticule of Graph.

Do not alter the setting of the 10kΩ resistor. 

With the Load Resistance (l 00k Ω resistor) removed from circuit I connected the pane l mount ed Mo vi ng Coil Meter as in Fig 2 .8 and s witched O N t he power supply.

Noted the effect on the output voltage rea ding of having the analog type meter connect ed in circuit as well a s the dig it a l multimeter. Multimeter voltage reading with the Moving Coil Meter connected= 

Compared this reading with the results on the characteristic curve of Graph and read off the graph the loading resistance presented by the Moving Coil Meter to the output: Loading resistance of the Moving Coil Meter = 

Enter your value of the loading resistance of the Moving Coil Meter in What you have observed here is a problem which can be very misleading if you are not aware of the difficulties of using a low impedance meter to take measurements in a high impedance circuit. The problem can be overcome by using a Buffer Amplifier.

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Modify the circuit to include Buffer #1 as in Fig and note the effect on the output voltage as indicated by both meters. Output voltage = 4.4V 

Enter your value of analog output voltage with Buffer #1 in circuit in volts.

Obj ect7

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Obj ect9

Conclusion: After performing this Experiment I can conclude that voltage varies directly with the resistance as general formula of ohm's Law say that V=IR.That have practically little curve on the straight line of Voltage and resistance graph.

2.4 - Practical Exercise Plot the Variation of Output voltage with Servo Potentiometer A special positional potentiometer is mounted o n t he experiments boar d which has a very large a r c of turning, approaching 360°. I t is call ed a Servo Potentiometer.

To bring the potentiometer scale int o cont act with the drive wheel on t h e shaft, press and release t h e mounting at the point arrowed in Fig. The potentiometer can t hen be turned manually with the shaft, using one of the large w h e e ls , such as the Hall Effect Sens or Disk. The potentiometer can be tur ned directly f r om the dial, manually, if preferred. The ±5V input voltages to the Servo Potentiometer are connected internally. 15

Connect a digit al multimeter on the 20V D C r ang e t o t he output o f the potentiometer as shown in F ig. Tur n the potentiometer to find the maxi m um positive output volt ag e position. Note the value of this voltage and the angle, as given on t h e potentiometer dial, in the first column of Table overleaf. Control Dial Set ting Output

150 4.5V

120

90

60

30

360

330

300

270

0

- 30

- 60

- 90

240 120

210 150

3.6V 2.73V 1.80V 0.9V 0.05V -0.85V -1.72V -2.60V -3.53V -4.37V

Rotate the dial in steps of 30° clockwise from the maximum voltage position (beginning with 150°), noting the output voltage at each step and recording the values in Table. At the final step note the angle from the dial setting and the value of the maximum negative voltage setting. From the information recorded in Table, draw the characteristic of the output voltage/dial setting of the Servo Potentiometer on the graticule on Graph.

Obj ect11

Conclusion & Discussion: In this experiment we observed that when a voltage applied across the ends of fixed track, the changing voltage obtained with the change in resistance. The output voltage will depend on the position of the variable contact because by changing the position we change the resistance so output voltages change and hence the output voltage indicates the position of the variable contact.

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Experiment # 3 Title: Wheatstone bridge Measurements Objectives:   

Set the offset control of null detector Measure the unknown resistance by using Wheatstone...