Lab manual Notes of emft, Lab Reports of Electronics

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EE3240 Instrumentation & Measurements Name: ______________________________________ Student ID: ______________________________________ Semester: Spring 2020 i Contents Course Learning Outcomes........................................................................................................................vii Rules and Guidelines.................................................................................................................................viii List of Experiments...................................................................................................................................... ix Lab Rubrics for Non-Programming Courses.................................................................................................x 1 Lab 1-Measuring Unknown Resistance Using Wheatstone bridge...................................................1-1 1.1 Objective..................................................................................................................................1-1 1.2 Theory......................................................................................................................................1-1 1.2.1 Bridge Circuits...................................................................................................................1-1 1.2.2 Balanced Wheatstone bridge............................................................................................1-1 1.3 Working principle of Wheatstone bridge.................................................................................1-2 1.3.1 Balanced and Unbalanced Condition of a Wheatstone bridge.........................................1-2 1.3.2 Measurement using Wheatstone bridge..........................................................................1-2 1.3.3 To measure the value of a resistor using Wheatstone bridge:.........................................1-2 1.3.4 Application of Wheatstone bridge....................................................................................1-3 1.3.5 Wheatstone bridge Light Detector...................................................................................1-4 1.4 Equipment................................................................................................................................1-4 1.5 Procedure.................................................................................................................................1-5 1.6 Results......................................................................................................................................1-5 1.7 Conclusion................................................................................................................................1-6 2 Lab 2 – Maxwell Bridge.....................................................................................................................2-1 2.1 Objective..................................................................................................................................2-1 2.2 Theory......................................................................................................................................2-1 2.2.1 AC Bridge Circuit...............................................................................................................2-1 2.2.2 Maxwell Bridge.................................................................................................................2-2 2.3 Working principle of Maxwell Bridge........................................................................................2-2 2.4 Equipment................................................................................................................................2-3 2.5 Procedure.................................................................................................................................2-3 2.6 Conclusion................................................................................................................................2-4 3 Lab 3 Schering Bridge.......................................................................................................................3-1 3.1 Objective..................................................................................................................................3-1 3.2 Theory......................................................................................................................................3-1 ii 9.5 Equipment................................................................................................................................9-4 9.6 Applications..............................................................................................................................9-4 9.7 Conclusion................................................................................................................................9-6 10 Lab 10 Interfacing Proximity Sensors..........................................................................................10-1 10.1 Objective................................................................................................................................10-1 10.2 Theory....................................................................................................................................10-1 10.2.1 Proximity sensor:............................................................................................................10-1 10.3 Equipment..............................................................................................................................10-1 10.4 Procedure...............................................................................................................................10-2 10.5 PROGRAM:..............................................................................................................................10-3 10.6 Observations:.........................................................................................................................10-3 11 Lab 11 LDR & RTD.......................................................................................................................11-1 11.1 Objective................................................................................................................................11-1 11.2 Theory....................................................................................................................................11-1 11.2.1 Introduction....................................................................................................................11-1 11.3 Procedure...............................................................................................................................11-2 11.3.1 In Light:...........................................................................................................................11-2 11.3.2 In Dark:...........................................................................................................................11-3 11.3.3 RTD.................................................................................................................................11-3 11.3.4 In Cold Temp:..................................................................................................................11-5 11.3.5 In hot Temp:...................................................................................................................11-5 11.3.6 Arduino Light Sensor Circuit using LDR...........................................................................11-5 11.4 Equipment..............................................................................................................................11-6 11.5 Testing....................................................................................................................................11-6 11.5.1 Code Explanation:...........................................................................................................11-7 11.6 Conclusion..............................................................................................................................11-8 12 Lab 12 Temperature & Pressure Sensors Interfacing..................................................................12-1 12.1 Objective................................................................................................................................12-1 12.2 Theory....................................................................................................................................12-1 12.2.1 Arduino Temperature and BMP085 pressure - Module GY-65.......................................12-1 12.2.2 Description.....................................................................................................................12-1 12.2.3 Specification...................................................................................................................12-1 12.3 Procedure...............................................................................................................................12-2 v 12.4 Equipment..............................................................................................................................12-4 12.5 Conclusion..............................................................................................................................12-4 13 Lab 13 Ultrasonic Sensors Interfacing.........................................................................................13-1 13.1 Objective................................................................................................................................13-1 13.2 Theory....................................................................................................................................13-1 13.2.1 Ultrasonic Sound.............................................................................................................13-1 13.2.2 Approximate frequency ranges:.....................................................................................13-1 13.2.3 Ultrasonic Sensor:...........................................................................................................13-2 13.2.4 Ultrasonic range finding..................................................................................................13-3 13.2.5 Ultrasound Identification (USID).....................................................................................13-3 13.2.6 Some Other Application:.................................................................................................13-4 13.3 Equipment..............................................................................................................................13-4 13.4 Procedure...............................................................................................................................13-5 13.4.1 Step 1..............................................................................................................................13-5 13.4.2 Step # 2...........................................................................................................................13-5 13.4.3 Step # 3...........................................................................................................................13-6 13.4.4 Step # 4...........................................................................................................................13-7 13.4.5 Step # 5...........................................................................................................................13-8 13.4.6 Step # 6...........................................................................................................................13-8 13.5 Result:.....................................................................................................................................13-9 13.6 Conclusion..............................................................................................................................13-9 14 Lab 14 TTL Conversion................................................................................................................14-1 14.1 Objective................................................................................................................................14-1 14.2 Theory....................................................................................................................................14-1 14.2.1 Key Features...................................................................................................................14-2 14.3 Procedure...............................................................................................................................14-2 14.4 Equipment..............................................................................................................................14-3 14.5 Results....................................................................................................................................14-3 14.6 Conclusions.............................................................................................................................14-4 vi Course Learning Outcomes A student who successfully fulfills the lab work requirements will have demonstrated the ability to: S. No. CLO Bloom’s Taxonomy Level Corresponding PLO 1. Use different type of sensors, transducers, and electronic measuring instruments. P3 Guided Response PLO-1 Engineering Knowledge 2. Analyze different bridge circuits for measurements of unknown values of components. P4 Mechanism PLO-4 Investigation 3. Apply operational and instrumentational amplifiers to manipulate signals for measurements. P4 Mechanism PLO-4 Investigation 4. Interface sensors to a digital system. P 3 Guided Response PLO-6 Modern Tool Usage 5. Design and develop a project according to given specifications. P4 Mechanism PLO-3 Design/Development of Solutions 6. Effectively work in a team project. A3 Valuing PLO-9 Individual and Teamwork vii Lab Rubrics for Non-Programming Courses  Lab Performance (5 Marks) 0 1 - 3 4 5 Student was unable to perform the required tasks. There was no attempt to make any arrangements to make up the lab. Student has partially implemented the required tasks. Student was able to perform the task but not very cleanly and precisely. Student performed the tasks cleanly and precisely.  Quality of Lab Report (3 Marks) 0 1 2 3 Student report is so incomplete and/or so inaccurate that it is unacceptable Student turned in an incomplete lab report with incomplete post-lab exercise. Student submitted a complete report and post-lab exercises with some lack of clarity. Student submitted a complete, neat and clean report with correct post-lab exercises.  Viva (2 Marks) 0 1 2 Student did not appear in the viva or has no idea of the theoretical concept of the experiment and its implementation. Student has unclear and weak concepts. Student has the required knowledge of the theoretical concepts along with the practical implementation. x 1 Lab 1-Measuring Unknown Resistance Using Wheatstone bridge 1.1 Objective To study and implement the balanced and unbalanced Wheatstone bridge by using galvanometer. 1.2 Theory 1.2.1 Bridge Circuits Bridge circuits are used to convert impedance variations into voltage variations. One of the advantages of the bridge for this task is that it can be designed so the voltage produced varies around zero. This means that amplification can be used to increase the voltage level for increased sensitivity to variation of impedance. Another application of bridge circuit is in the precise static measurement of impedance. A basic type of bridge circuit is shown in figure 1, where four resistances are connected. A galvanometer or voltmeter is used to compare the potentials of points a and b of the circuit. If the current through the galvanometer is zero OR the potential difference across points a and b is zero then the bridge circuit is known as Balanced bridge circuit. In balanced bridge circuit the relation among the resistances is given as: R1R4 = R2R3 1.2.2 Balanced Wheatstone bridge Wheatstone bridge is a simple bridge circuit of resistors, consisting of four resistors, with two branches in parallel and each branch with two resistors in series as shown in the figure below: Figure 1-1: Wheatstone bridge Where, R1, R2 are resistors, R and Rs are also resistors and G is a galvanometer. The Wheatstone bridge is the most widely used circuit for precisely measuring resistance by the comparison method. Wheatstone bridge is actually invented by Samuel Hunter Christie during 1833 and Wheatstone bridge is named after Charles Wheatstone who popularized it in 1843. The Wheatstone bridge circuit is nothing more than two simple series-parallel arrangements of resistors connected between a voltage supply terminal and ground producing zero voltage difference when the two parallel resistor legs are balanced. A Wheatstone bridge circuit has two input terminals and two output terminals consisting of four resistors configured in a diamond-like arrangement as shown. This is typical of how the Wheatstone bridge is drawn. Figure 1-2: Circuit diagram of Wheatstone bridge 1.3 Working principle of Wheatstone bridge 1.3.1 Balanced and Unbalanced Condition of a Wheatstone bridge In most cases the Wheatstone bridge is unbalanced and it is so called when some current is flowing through the galvanometer. But in the case, when the values of R1, R2 and Rs are so adjusted; such that no current flows through the bridge galvanometer; this state is called the balanced state of Wheatstone bridge. 1.3.2 Measurement using Wheatstone bridge A Wheatstone bridge as shown below can be used to measure the resistance of the resistor “R”. Figure 1-3: Measurement using Wheatstone bridge 1.3.3 To measure the value of a resistor using Wheatstone bridge: To measure the value of a resistor using Wheatstone bridge the resistor of which the value is to be measure is placed on the branch AD. The two resistors of a known value and in a fixed ratio such as R1:R2 = K: 1 is placed on the branch AB and BC. 2 2. DC Power Supply 3. Resistors 4. Connecting wires 1.5 Procedure Follow the steps for experiments given below: 1. Connect the circuit as shown in figure 2. Set the DC voltage supply to 10 Volts. 3. Adjust the variable resistor R3 until current through the volt-meter becomes zero. 4. Without altering R3, remove it from the circuit and measure its resistance using an ohmmeter and write in the following table. 1.6 Results W. bridge R1 R2 R3 R4 V1 V2 V3 V4 I1 I2 Balanced Unbalance d Verification of Balanced Bridge Principle: R1 R4 R2R3 A galvanometer is a device that measures electrical current and the direction it is flowing. When electricity passes through the coil the measurement is shown by a magnetic needle. A galvanometer is a type of sensitive ammeter: an instrument for detecting electric current. It is an analog electromechanical actuator that produces a rotary deflection of some type of pointer in response to electric current flowing through its coil in a magnetic field. Galvanometers were the first instruments used to detect and measure electric currents. 5 Figure 1-7: Analog Measurement 1.7 Conclusion 1. Discuss different types of Bridges? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the basic working principle of Wheatstone bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. Why Wheatstone bridge is so commonly used? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. What is the main advantage of Maxwell Wien Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5. Write down any three applications of Wheat stone bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 7 And Y1 = 1/R1 + jωCωCC1 Substituting of these values in above equation (1) ZX=RX+ jw LX=R2 R3 ¿ + jw C1) Separation of the real and imaginary terms RX= R2 R3 R1 , LX = R2R3C1 Figure 2-3: Maxwell Bridge for inductance measurement 2.4 Equipment 1. Galvanometer 2. DC Power Supply 3. Function Generator 4. Resistors 5. Variable capacitor 6. Inductor 7. Connecting wires 2.5 Procedure 1. Connect the circuit as shown in figure 2. Set the AC voltage supply to 10 Volts and frequency at 1 kHz. 3. Adjust the variable resistor and variable Inductor until current through the volt-meter/Galvanometer becomes zero. 3 4. Without altering resistor and capacitor, remove it from the circuit and measure its resistance using an ohmmeter and write in following table. Maxwell Bridge Known values Unknown values R1 R2 R3 C 1 LX RX V 1 V 2 V 3 I 1 I 2 True value of Inducto r (mH) Measure d Value of Inductor (mH) Erro r (%) Dissipatio n Factor Balanced Unbalance d 2.6 Conclusion 1. What are the types of AC Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the basic working principle of Maxwell Bridge?. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. What is the other name for Maxwell inductance Capacitance Bridge? 4 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. What is the main advantage of Maxwell Wien Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5. What is the main disadvantage of Maxwell Wein Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 And expanding RX− j wC3 =¿ R2C1 C3 - J R2 WC3 R1 Equating the real terms, we find that RX=R2 C1 C3 and CX=C3 R1 R2 3.4 Equipment 1. Galvanometer 2. DC Power Supply 3. Function Generator 4. Resistors 5. Variable capacitor 6. Inductor 7. Connecting wires 3.5 Procedure 1. Connect the circuit as shown in figure 2. Set the AC voltage supply to 10 Volts and frequency at 1 kHz. 3. Adjust the variable resistor and variable capacitor until current through the volt-meter/Galvanometer becomes zero. 4. Without altering resistor and capacitor, remove it from the circuit and measure its resistance using an ohmmeter and write in following table. Schering Bridge Known values Unknown values R1 R2 R3 C 1 LX RX V 1 V 2 V 3 I 1 I 2 True value of Inducto r (mH) Measure d Value of Inductor (mH) Erro r (%) Dissipatio n Factor Balanced Unbalance d 3.6 Conclusion 1. Define the basic principle of Schering Bridge? 3 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the difference between Maxwell Bridge, Hay Bridge and Schering Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. Draw the circuit diagram of Schering Bridge. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. What are the advantages of Schering Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 5. What are the measurement factors of Schering Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 R2 R4 = R1 R3 + C3 C1 And, 1 wC1 R3 =wC3 R1 w2= 1 C1R1C3R3 , w = 2πff f = 1 2π √C1 R1C3 R3 4.3 Equipment 1. Galvanometer 2. Function Generator 3. Resistors 4. Variable capacitor 5. Capacitor 6. Connecting wires 4.4 Procedure 1. Connect the circuit as shown in figure 2. Set the AC voltage supply to 10 Volts. 3. Adjust the variable frequency until current through the volt-meter/Galvanometer becomes zero. 4. Without altering resistor and capacitor, remove it from the circuit and measure its resistance using an ohmmeter and write in following table. Wein Bridge Known values Unknown values R1 R2 R3 C 1 LX RX V 1 V 2 V 3 I 1 I 2 True value of Inducto r (mH) Measure d Value of Inductor (mH) Erro r (%) Dissipatio n Factor Balanced Unbalance d 4.5 Conclusion 1. Define the basic principle of Wien Bridge? 3 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the difference between Wien Bridge, Maxwell Bridge, Hay Bridge and Schering Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. Draw the circuit diagram of Wien Bridge?. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. What are the advantages of Wein Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 ______________________________________________________________________ 5. What are the measurement factors of Wein Bridge? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 5.4 Procedure 5.4.1 Summing Amplifier 1. Connect the circuit as shown in figures to construct summer and subtractor circuit respectively. 2. Vary the voltages in RPS and observe the output voltages. 3. Check the result with the theoretical values. 5.4.2 Differential Amplifier 1. Connect the circuit as shown in figures to construct summer and subtractor circuit respectively. 2. Vary the voltages in RPS and observe the output voltages. 3. Check the result with the theoretical values. 5.5 Conclusion 1. Construct a differential amplifier that produces V2 – V1 output? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. Construct a summing amplifier that produces – (V1 + V2) output? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. Discuss applications of differential amplifiers? ______________________________________________________________________ 3 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. Discuss applications of summing amplifiers? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 6 Lab 6 Measuring output impedance of a circuit 6.1 Objective To study impedance concepts & to measure output impedance of a circuit 6.2 Theory 6.2.1 Measuring output impedance of a circuit The output impedance of an operational amplifier, often designated Zo, arises from the fact that the output driver circuit and the associated connections have a defined impedance. The output impedance can be split for many applications. The resistance element is of primary importance and is the major component of the overall impedance. However for some cases the reactance may also be an issue and this is caused mainly by the series inductance. To be fair, the reactive elements are normally small and are ignored for most op amp applications. Typically the frequencies at which op amps are used, the reactance levels will be small and not affect the circuit operation unduly. However they should not be forgotten as they may have an effect in some instances. Figure 6-1: Output impedance of an op-amp As can be seen from the diagram, the op amp output resistance is the DC resistance that appears in series with the output from an ideal amplifier located within the chip. In other words the output resistance can be measured by looking at the voltage drop caused when a defined load is added to the output. In most cases the output resistance is very low and very little drop will be seen. The major issue is normally that if reaching the limit of the current that the op amp will supply. Also the reactance should not be ignored. High frequency operational amplifiers are available and the reactance can be such that it needs to be considered for any calculations. 6.3 Practical issues When looking at data sheets to discover the output impedance. Dependent upon the manufacturer, data sheets may list the output impedance under one of two different conditions. Some list closed-loop output impedance while others list open-loop output impedance. Confusingly both tend to use the designation Zo. If using the op amp for an input stage, then it may well be advisable to choose a low noise op amp. 6.8 Low power / current With many items requiring to be battery powered these days, low power consumption can be an issue. Many op amps have been designed for these applications, and by searching, it is possible to choose some very low power op amps. 6.9 Low supply voltage Early op amps used to run from supplies that might be ±15V. Nowadays with many circuits needing to run from much lower supplies these voltages are not practicable in many instances. Fortunately it is possible to choose low voltage op amps. 6.10 Choosing the right op amp package When choosing an op amp, it is also necessary to select the package type. The chips can be obtained in a variety of different packages, both conventional though hole mounting in 4 and 8 pin dual in line as well as a variety of surface mount packages as well. Also don’t forget that it is possible to select packages with multiple op amps within them. Typically they can come with two and four op amps per package, although higher counts are available. These can save space on the board and cost. When opting for the higher number op-amps per package, remember these multiple devices per package do not normally come with offset null connections. Check this before choosing the device if offset null is required. 6.11 Equipment 1. Op-Amp IC 741 2. Dual power Supply 15V 3. Resistor 4. Capacitors 5. Function Generator 6. Digital Oscilloscope 7. Multimeter 8. Breadboard and Connecting wires. 4 6.12 Procedure Figure 6-3: High impedance, analog DC voltmeter Select R such that the meter movement in figure will read the full scale when v¿=10 vdc . Construct the circuit shown in figure and verify its operation. Record the position of the meter movement for v¿=0V ,2V ,4 V ,6V ,8V∧10V . A value for the resistance 'R' was selected to set the meter movement to read full-scale at an input voltage Vin = 10VDC. It was determined that R = 10kΩ where the current through 'R' was equal to 1mA (max). Next the circuit was constructed (Figure 1) to examine the devices characteristics. Once constructed specific input voltages were selected and the meters output voltage was measured and recorded (Table 1). Table 1: Measured Values for Ideal 741 High Impedance DC Voltmeter v¿ (volts) I ¿=¿ (Expected mA) I ¿=¿ (Measured) Difference 0 0 2 0.023 4 0.406 6 0.61 8 0.813 10 1.016 6.13 Conclusion 1. What are output impedance elements of Op-amp? ______________________________________________________________________ ______________________________________________________________________ 5 ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the significance of having impedance measurements? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. Enlist any 02 applied fields of impedance measurements? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 For the input loop, the voltage equation is: V ¿=V D+V FSince A is very large , V D=0 So, V ¿=V FSince, the input to the Op-amp, I 'B= 0 V ¿=I L X R Therefore, I 1=I L= V ¿ R From the above equation, it is clear that the load current depends on the input voltage and the input resistance. That is, the load current, , which is the input voltage. The load current is controlled by the resistor, R. Here, the proportionality constant is 1/R. So, this converter circuit is also known as Trans-Conductance Amplifier. Other name of this circuit is Voltage Controlled Current Source. The type of load may be resistive, capacitive or non-linear load. The type of load has no role in the above equation. When the load connected is capacitor then it will get charge or discharge at a steady rate. Due to this reason, the converter circuit is used for the production of saw tooth and triangular wave forms. 7.6 Equipment 1. Op-Amp IC 741 2. Dual power Supply 15V 3. Resistor 4. Capacitors 5. Function Generator 6. Digital Oscilloscope 7. Multimeter 3 7.7 Procedure 7.7.1 Ground Load Voltage to Current Converter This converter is also known as Howland Current Converter. Here, one end of the load is always grounded. For the circuit analysis, we have to first determine the voltage, V IN and then the relationship or the connection between the input voltage and load current can be achieved. - Figure 7-3: Ground load to voltage conversion For that, we apply Kirchhoff’s current law at the node V1 I1 + I2 = IL VIN−V 1 R + VO−V 1 R = IL V 1= V ¿+V O−I L 2 VIN + VO -2V1 = IL R For a non-inverting amplifier, gain is A = 1 + RF R1 4 Here, the resistor, RF=R=R1 . So, A = 1 + R R = 2 Hence the voltage in the output will be V O=2V 1=V ¿+V O−I L R 0=V ¿−I L R But, V ¿=I L R I L= V ¿ R Thus, can conclude from the above equation that the current IL is related to the voltage, VIN and the resistor, R. 7.8 Application of Voltage to Current Converter  Zener diode tester  Low AC and DC Voltmeters  Testing LED  Testing Diodes 5 Figure 7-4: Application of Op-amp 8.2.2 Current Buffer: Typically a current buffer amplifier is used to transfer a current from a first circuit, having a low output impedance level, to a second circuit with a high input impedance level. The interposed buffer amplifier prevents the second circuit from loading the first circuit unacceptably and interfering with its desired operation. In the ideal current buffer in the diagram, the input impedance is zero and the output impedance is infinite (impedance of an ideal current source is infinite). Again, other properties of the ideal buffer are: perfect linearity, regardless of signal amplitudes; and instant output response, regardless of the speed of the input signal. 8.3 Equipment 1. Digital Multimeter 2. Oscilloscope 3. LM-741 op-amp. 4. 10kΩ, 22kΩ, 33kΩ, 47kΩ and 82kΩ resistors. 5. Dual Power Supply. 8.4 Procedure Consider the circuit given below: Figure 8-3: Op-amp connections 2 Figure 8-4: 741 pin specification 8.5 Observations S.No V ¿ V ¿ V out Theoretical V out Measured Theoretical Values Experimental Values 1 2 3 8.6 Conclusion 1. What is the purpose of a buffer circuit? ______________________________________________________________________ _______________ _______________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What are buffers in electronics?? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 3. What does a unity gain buffer do? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4. Will the current be high or low in a voltage follower circuit? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 Vout= (V1– V2)(1+50K/RG) This simplifies the transfer function and allows one resistor (RG) to decide the overall gain. The smaller resistor selected for RG will create a large gain, while a large resistor will create a small gain. Table 1 gives examples of different gain values and their associated RG value. Desired Gain RG (Ohms) 1 None 2 50K 5 12.5K 10 5.556K 20 2.632K 50 1.02K 100 505.1 200 251.3 500 100.2 1000 50.05 2000 25.01 5000 10 Table: Gain and Resistor Values For this application note, a gain of 10 was selected, which would make RG a value of 5.5KOhm. 9.4 Testing the Design To ensure the design is working properly, it must be tested. In order to test the circuit, a few different lab machines are required, such as: an oscilloscope, a function generator and two power supplies. First, one must set the power supplies to +15 V and -15 V. This is the typical operation voltage for the LM324 op amp. Next, the circuit should be built on a breadboard so that it is easy to interchange components. The pin-out for the LM324 is shown in figure 4. Once the circuit is built, set the function generator to a 500 mVpp SIN wave at 1 KHz and input it to V1, as shown in figure 5. Also, one must ground the other input terminal. In order to test the gain of the instrumentation amp, one must place an oscilloscope scope probe on the function generator and another on the output of the amplifier. With the power supplied to the circuit and a proper waveform as an input, one should see an output similar to figure 6. Figure 6 displays the input and the output on the same time scale, but different voltage scales. To ensure the gain is about 10, take the output voltage and divide it by the input voltage. This example has Vout/Vin = 5.046 V/513.66 mV = 9.82. 3 Figure 9-4: Waveform 9.5 Equipment 1. Digital Multimeter 2. Oscilloscope. 3. LM324 IC 4. 10kΩ, 22kΩ, 33kΩ, 47kΩ and 82kΩ resistors. 5. Dual Power Supply. 9.6 Applications Instrumentation amplifiers are used in many different circuit applications. Their ability to reduce noise and have a high open loop gain make them important to circuit design. Figures 1-3 illustrate several different applications that utilize instrumentation amplifiers. The instrumentation amplifiers shown in figures 1-3 are the INA128. Figure 9-5: Applications of amplifiers 4 Figure 1. Bridge Amplifier NOTE: Due to the INA128's current-feedback topology, Vg is approximately 0.7V less than the comman-mode input voltage. This DC offset in this guard potential is satisfactory for many guarding applications. Figure 2. ECG Amplifier 9.7 Conclusion V+ 10.0V 6 J REF102 [> = Ay Ry wy ‘ Pt100 Cu ~ SF \/ cu) ra INA128 o = Ra x ea 100Q = Pti00 at 0°C Figure 3. Thermocouple Amplifier Figure 9-6: Applications of Instrumentational amplifier 10 Lab 10 Interfacing Proximity Sensors 10.1 Objective Interfacing Proximity Sensor to a Digital System To compute the wind speed using proximity sensor and Arduino 10.2 Theory 10.2.1 Proximity sensor: A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor's target. Different proximity sensor targets demand different sensors. For example, a capacitive photoelectric sensor might be suitable for a plastic target, an Inductive proximity sensor always requires a metal target. The maximum distance that this sensor can detect is defined "nominal range". Some sensors have adjustments of the nominal range or means to report a graduated detection distance. Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between sensor and the sensed object. Figure 10-1: Inductive Proximity sensor 10.3 Equipment 1. Arduino UNO board 2. Proximity sensor (inductive) 3. Wind vane setup 4. Connecting wires 5. Arduino software 10.4 Procedure To interface a sinking proximity sensor to an Arduino. When the sensor is activated a green LED lights up and a tone is generated from a speaker. When the sensor is inactivated a red LED lights up. CIRCUIT DIAGRAM: Figure 10-2: Speed sensing circuity 2 Figure 10-3: Overall Hookup for PNP sensor 10.5 PROGRAM: Void setup() { Serial.begin(9600); pinMode(A0,INPUT); } Void loop(); { int pulse=analogRead(A0); int conversion=pulse*(5/1023); int speed=conversion*0.9716; Serial.print(“Speed=”); Serial.print(speed); } 10.6 Observations: Serial Monitor: 3 11 Lab 11 LDR & RTD 11.1 Objective To study and implement LDR sensor and RTD sensor. Interfacing LDR sensor and RTD sensor to a Digital System 11.2 Theory 11.2.1 Introduction LDR (light Dependent Resistor) A photo resistor or light-dependent resistor (LDR) or photocell is a light-controlled variable resistor. The resistance of a photo resistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photo resistor can be applied in light-sensitive detector circuits, and light- and dark-activated switching circuits. LDR is Light Dependent Resistor. LDRs are made from semiconductor materials to enable them to have their light-sensitive properties. There are many types but one material is popular and it is cadmium sulfide (CdS). These LDRs or PHOTO RESISTORS works on the principle of “Photo Conductivity”. Now what this principle says is, whenever light falls on the surface of the LDR (in this case) LDRs or Light Dependent Resistors are very useful especially in light/dark sensor circuits. Normally the resistance of an LDR is very high, sometimes as high as 1000 000 ohms, but when they are illuminated with light resistance drops dramatically. Figure 11-1: Light dependent resistor This is an example of a light sensor circuit : When the light level is low the resistance of the LDR is high. This prevents current from flowing to the base of the transistors. Consequently the LED does not light. However, when light shines onto the LDR its resistance falls and current flows into the base of the first transistor and then the second transistor. The preset resistor can be turned up or down to increase or decrease resistance, in this way it can make the circuit more or less sensitive. 11.3 Procedure 1. Connect the circuit as shown in figure 2. Set the DC voltage supply to 12 Volts. And measure the voltage, Current at different points of circuit. 11.3.1 In Light: S.No VCC VB VBE VR VLED VLDR Ic(mA) IB(mA) IE(mA) Light (Luminance ) 1 0V 2 0.5v 3 1.5V 4 3V 5 5V 2 Figure 11-2: Light sensor circuit 11.3.2 In Dark: S.No VCC VB VBE VR VLED VLDR Ic (mA) IB (mA) IE (mA) Light (Luminance ) 1 0V 2 0.5v 3 1.5V 4 3V 5 5V 11.3.3 RTD A thermistor is a type of resistor whose resistance varies significantly with temperature, more so than in standard resistors. The word is a portmanteau of thermal and resistor. Thermistor are widely used as inrush current limiters, temperature sensors, self-resetting over current protectors, and self-regulating heating elements. There are two kinds of of thermistors, NTC (negative temperature coefficient) and PTC (positive temperature coefficient). Thermistors can be classified into two types, depending on the classification of . If is positive, the resistance increases with increasing temperature, and the device is called a positive temperature coefficient (PTC) thermistor, or posistor. If is negative, the resistance decreases with increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor. Resistors that are not thermistors are designed to have a as close to zero as possible, so that their resistance remains nearly constant over a wide temperature range. Thermistor differ from resistance temperature detectors (RTD) in that the material used in a thermistor is generally a ceramic or polymer, while RTDs use pure metals. The temperature response is also different; RTDs are useful over larger temperature ranges, while thermistor typically achieve a higher precision within a limited temperature range, typically −90 °C to 130 °C. Like the RTD, the thermistor is also a temperature sensitive resistor. While the thermocouple is the most versatile temperature transducer and the PRTD is the most stable, the word that best describes the thermistor is sensitive. Of the three major categories of sensors, the thermistor exhibits by far the largest parameter change with temperature. Thermistors are generally composed of semiconductor materials. Although positive temperature coefficient units are available, most thermistor have a negative temperature coefficient (TC); that is, their resistance decreases with increasing temperature. The negative T.C. can be as large as several 3 Figure 11-4: Arduino based LDR circuit 11.4 Equipment 1. Arduino UNO 2. LDR (Light Dependent Resistor) 3. Resistor (100k-1;330ohm-1) 4. LED – 1 5. Connecting wires 6. Breadboard 7. Transistor 8. RTD 9. Capacitor 10. bulb/CFL 11.5 Testing Figure 11-5: Arduino board Connection 6 11.5.1 Code Explanation: Here, we are defining the Pins for Relay, LED and LDR. #define relay 10 int LED = 9; int LDR = A0; Setting up the LED and Relay as Output pin, and LDR as input pin. pinMode(LED, OUTPUT); pinMode(relay, OUTPUT); pinMode(LDR, INPUT); Reading the voltage analog value through the A0 pin of the Arduino. This analog Voltage will be increased or decreased according to the resistance of LDR. Reading the voltage analog value through the A0 pin of the Arduino. This analog Voltage will be increased or decreased according to the resistance of LDR. int LDRValue = analogRead(LDR); Giving the condition for dark and bright. If the value is less than 700 then it is dark and the LED or Light turns ON. If the value is greater than 700 then it is bright and the LED or light turns OFF. if (LDRValue <=700) { digitalWrite(LED, HIGH); digitalWrite(relay, HIGH); Serial.println("It's Dark Outside; Lights status: ON"); } else { digitalWrite(LED, LOW); 7 digitalWrite(relay, LOW); Serial.println("It's Bright Outside; Lights status: OFF"); } 11.6 Conclusion 1. What is the role of the preset resistor? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. What is the difference between LDR and RTD? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3. What is the difference between RTD and Thermistor? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8  High linear mode, a resolution of 0.03hPa (0.25 meters)  With temperature output  I2C interface  Temperature compensation  Lead-free, RoHS compliant  MSL 1  Reaction time: 7.5ms  Standby current: 0.1μA. BMP085 powerful 8-pin ceramic leadless chip carrier (LCC) ultra-thinA  No external clock circuit 12.3 Procedure To interface BMP085 atmospheric pressure sensor module with arduino, which is the temperature module and BMP085 pressure follow the provided instructions: Figure 12-2: temperature module and BMP085 pressure module 2 The name BMP085 comes from the name given to the sensor itself, as we see in the datasheet . In the case of the photo above module, the module code is GY-65. The module works with a voltage of 1.8 to 3.6V. Its pressure reading range is 300 to 1100 hPa (hectoPascal), which determines altitudes from 9000 meters above sea level by -500m. The connection to the controller is made by only 2 pins, using the I2C interface. Use a library Adafruit, which you can download at that address . A parenthesis about this library is that when decompressing, the folder name is "Adafruit-BMP085-Library- master" .Unfortunately, the IDE does not accept name folder libraries with numbers and special characters, then rename the folder just for " BMP085 ". . Use the 1.0.5 version of the Arduino IDE. Figure 12-3: Arduino board connectivity Take care not to reverse any connection to connect the wires, because usually the marking pins comes under the plate, getting hidden when you fit into the breadboard. The program below is based on the test program that comes along with the library, with the due translations to facilitate understanding: 3 Code Explanation: // Program: Pressure test module BMP@s5 // Author: Adafruit ff translations and commentaries: Arduino and Co. #include <Wire.h> #include <[email protected]> #/ Connect Vcc pin of the BMP@85 to the Arduino pin 3.3V (5.@V NOT USE!) // Connect GND pin module to the Arduino GND // Connect the SCL pin module to analog pin 5 Arduino // Connect pin SDA module to pin 4 of analog Arduino // pin EOC (end of conversion) unused // XCLR pin is a reset pin is not used Adafruit_BMP@gS bmp; void setup () Serial.begin ( 9600 ); if (bmp.begin ()) { Serial.println ( “Sensor BHP@35 not found, check the connections!” ); While (1) {} i 13 Lab 13 Ultrasonic Sensors Interfacing 13.1 Objective To study & implement the Ultrasonic Sensor. Interfacing Ultrasonic Sensor with a digital system 13.2 Theory 13.2.1 Ultrasonic Sound An Ultrasonic Sensor is a device that measures distance to an object using Sound Waves. It works by sending out a sound wave at ultrasonic frequency and waits for it to bounce back from the object. Then, the time delay between transmission of sound and receiving of the sound is used to calculate the distance. It is done using the formula Distance = (Speed of sound * Time delay) / 2 We divide the distance formula by 2 because the sound waves travel a round trip i.e from the sensor and back to the sensor which doubles the actual distance. The HC-SR04 is a typical ultrasonic sensor which is used in many projects such as obstacle detector and electronic distance measurement tapes. Ultrasound is an oscillating sound pressure wave with a frequency greater than the upper limit of the human hearing range. Ultrasound is thus not separated from 'normal' (audible) sound by differences in physical properties, only by the fact that humans cannot hear it. Although this limit varies from person to person, it is approximately 20 kilohertz (20,000 hertz) in healthy, young adults. Ultrasound devices operate with frequencies from 20 kHz up to several gigahertz. Figure 13-1: Spectrum 13.2.2 Approximate frequency ranges: Approximate frequency ranges corresponding to ultrasound, with rough guide of some applications Ultrasound is used in many different fields. Ultrasonic devices are used to detect objects and measure distances. Ultrasonic imaging (sonography) is used in both veterinary medicine and human medicine. In the nondestructive testing of products and structures, ultrasound is used to detect invisible flaws. Industrially, ultrasound is used for cleaning and for mixing, and to accelerate chemical processes. Animals such as bats and porpoises use ultrasound for locating prey and obstacles. Ultrasonic is the application of ultrasound. Ultrasound can be used for medical imaging, detection, measurement and cleaning. At higher power levels, ultrasonic is useful for changing the chemical properties of substances. 13.2.3 Ultrasonic Sensor: Ultrasonic sensors (also known as transceivers when they both send and receive, but more generally called transducers) work on a principle similar to radar or sonar which evaluates attributes of a target by interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate high frequency sound waves and evaluate the echo which is received back by the sensor. Sensors calculate the time interval between sending the signal and receiving the echo to determine the distance to an object. This technology can be used for measuring wind speed and direction (anemometer), tank or channel level, and speed through air or water. For measuring speed or direction a device uses multiple detectors and calculates the speed from the relative distances to particulates in the air or water. To measure tank or channel level, the sensor measures the distance to the surface of the fluid. Further applications include: humidifiers, sonar, medical ultrasonography, burglar alarms and non-destructive testing. Systems typically use a transducer which generates sound waves in the ultrasonic range, above 18,000 hertz, by turning electrical energy into sound, then upon receiving the echo turn the sound waves into electrical energy which can be measured and displayed. Figure 13-2: Various Ultrasonic sensors 2 13.2.4 Ultrasonic range finding A common use of ultrasound is in underwater range finding; this use is also called Sonar. An ultrasonic pulse is generated in a particular direction. If there is an object in the path of this pulse, part or all of the pulse will be reflected back to the transmitter as an echo and can be detected through the receiver path. By measuring the difference in time between the pulse being transmitted and the echo being received, it is possible to determine the distance. The measured travel time of Sonar pulses in water is strongly dependent on the temperature and the salinity of the water. Ultrasonic ranging is also applied for measurement in air and for short distances. For example hand-held ultrasonic measuring tools can rapidly measure the layout of rooms. Figure 13-3: Ultrasonic range finding mechanism 13.2.5 Ultrasound Identification (USID) Ultrasound Identification (USID) is a Real Time Locating System (RTLS) or Indoor Positioning System (IPS) technology used to automatically track and identify the location of objects in real time using simple, inexpensive nodes (badges/tags) attached to or embedded in objects and devices, which then transmit an ultrasound signal to communicate their location to microphone sensors. 3 Trig (Trigger) Echo (Receive) The key features to be noted are: Operating Voltage: 5V DC Operating Current: 15mA Measure Angle: 15° Ranging Distance: 2cm - 4m 13.4.3 Step # 3 Figure 13-7: Coding Step 3 6 The Serial Monitor is a part of the Arduino IDE. It is also available in the Web IDE. It allows you to send and receive data from the board connected via USB. This is using the concept of Serial Communication. You can send the commands by typing in the window on the top and pressing 'Enter' or clicking 'Send'. The data from the board is displayed below that. This is very useful when debugging the code, or if you need to give inputs to the board, this is probably the most useful tool in the IDE. The more you use it, the better you get at testing complex projects that takes inputs and provides consequent outputs. 13.4.4 Step # 4 Figure 13-8: The circuit The connections are as follows:  Vcc to 5V Pin of the Arduino.  Gnd to Gnd Pin of the Arduino.  Trig to Digital Pin 9 .  Echo to Digital Pin 10. Refer the schematics for more clarity on the connections. . Few things to remember while building the circuit  Avoid placing the sensor on metal surfaces to avoid short circuits which might burn the sensor.  It is recommended to put electrical tape on the back side of the sensor. 7  You can also directly connect the Ultrasonic sensor to the Arduino with jumper wires directly. 13.4.5 Step # 5 13.4.6 Step # 6 8 Figure 14-1: TTL gate levels If a voltage signal ranging between 0.8 volts and 2 volts were to be sent into the input of a TTL gate, there would be no certain response from the gate. Such a signal would be considered uncertain, and no logic gate manufacturer would guarantee how their gate circuit would interpret such a signal. 14.2.1 Key Features  Brand Name:LOGOELE  Camera Equipped:No  Compatibility:Others  Model Number:D196  State of Assembly:Almost Ready  is_customized:yes  Compatible:Game Console  working voltage:DC 4-30V  Size:28mm wide X 10mm high X12mm long  main chip:LM35 temperature sensor  wide operating voltage range:DC4-30V  Output:TTL level signal output 14.3 Procedure Connect temperature sensor probes as shown: 2 Figure 14-2: LM35D Signal output indicator Figure 14-3: LM35D sensor module dimensions 14.4 Equipment  LM35D sensor module 14.5 Results S.No Input Parameter Output Parameter Temperature rating 3 14.6 Conclusions 1. A very important concept to understand in digital circuitry is the difference between current sourcing and current sinking. Explain? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2. Compare LM 35 Temperature sensor Vs LM35D temperature sensor module? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4