SKEE 2742 BASIC ELECTRONICS LAB

Transcription

1 Faculty: Subject Subject Code : SKEE 2742 FACULTY OF ELECTRICAL ENGINEERING : 2 ND YEAR ELECTRONIC DESIGN LABORATORY Review Release Date Last Amendment Procedure Number : 1 : 2013 : 2013 : PK-UTM-FKE-(0)-10 SKEE 2742 BASIC ELECTRONICS LAB EXPERIMENT 3 OP-AMP

2 PART A : LINEAR OP-AMP APPLICATIONS : INVERTING SUMMING AND DIFFERENCE AMPLIFIERS OBJECTIVES : To demonstrate the use of Operational Amplifier for performing mathematical operations summing and difference. PARTS AND EQUIPMENT: DC Power Supply Oscilloscope Function Generator LM 741 Op-amp Resistors Protoboard PREPARATION/PRE-LAB ASSIGNMENTS/SIMULATIONS (Note: This pre-lab must be done before lab session and will be collected in the beginning of lab session) R F 12 V V 1 R V s = 1V pk V 2 5V R V 6 V O Note: pk = peak Figure 1 1

3 1. For the Inverting Summing Amplifier circuit of Figure 1, (i) Derive the output equation, VO. (ii) Get the mathematical expression for the output waveform, VO given in Figure 2. (iii) Determine the value of R1 and R2 when RF is equal to 100k. (Hint: Use answer in (ii)) (iv) Generate the output voltage waveform, VO using Multisim if VS is a sine wave or square wave of 1Vpk with a frequency 1kHz and V2 is a DC voltage of 5V. Print out the curve plot as a function of Voltage (V) against time (t). V O (V) t(ms) Figure 2 2. For the Difference Amplifier circuit of Figure 3, (i) (ii) Derive the output equation, VO. Generate the output voltage waveform using Multisim if V1 is a sine wave or a square-wave of 1 Vpk, and V2 is a DC voltage of 5 V. Print out the curve plot as a function of amplitude against time. 2

4 R F = 100 kω V 1 R 1 = 47 kω 2 12 V 7 V s = 1V pk V 2 R 2 = 100 kω 5V R 3 47 kω V 6 V O Figure 3 3. For the Comparator circuit of Figure 4, (i) Simulate the circuit in Multisim or of any equivalent software. The purpose of potentiometer, R is to set a variable reference voltage between VCC and VCC that can be applied as VREF to the op-amp. Note that changing the setting (%) of the potentiometer changes the voltage on the associated terminal. Set the signal generator (Vsig) for a 3 V pp triangle waveform at 1 KHz. Set the value of VREF for several positions of the potentiometer. Select both positive and negative values of VREF. Print out the Vsig and Vout as a function of time waveforms for 4 different combinations of potentiometer settings: a) VREF = 0 b) VREF ±Vm sin t c) 0< VREF Vm d) -Vm VREF < 0 (Note: pp stands for peak-to-peak, use virtual OP-AMP if OP-AMP 741 not available) 3

5 Vsig = Vm sinωt Figure 4 (ii) Print out the tranfer curve (V out vs V sig) for the comparator by clicking B/A on the oscilloscope. Choose 3 values of VREF including the one that will produce a square wave at the output. Mark the transition points (Vsig that causes Vout to change state) and record the reference voltage (Vref). 4. For a Schmitt Trigger circuit, (i) Derive the output equation, VO for the given circuit in Figure 5. (ii) From the given values of Upper Threshold Point, VUTP and Lower Threshold Point, VLTP in Figure 6, determine the values of R1 and R2 if the sum of R1 and R2 is equal to 51.7k. (iii) Simulate the circuit in Figure 5 using Multisim if the input voltage, VS is a sine wave of 8Vpk with a frequency 1kHz and Vref is a DC voltage of 5V. Print out the curve plot as a function of Voltage (V) against time (t) and the transfer curve (VO vs VS) by clicking B/A on the oscilloscope. (Note: Use 741 or COMPARATORVIRTUAL) 4

6 Figure 5 V O (V) V S (V) - 12 Figure End of pre-lab activity

7 IN-LAB PROCEDURES Part 1 : Inverting Summing Amplifier 1. Construct the circuit in Figure 1 with the values of R1 and R2 obtained from your pre-lab. 2. Set the input voltage, VS to 1Vpk (sine wave) with a frequency of 1kHz. 3. Record the output voltage, VO and observe the phase difference between the input and output. (Note the DC level in the output) 4. Compare your simulation with the experimental results. 5. Exchange the 5V DC power supply with the 1Vpk signal generator and vice versa. Repeat procedures 2 & 3. Part 2 : Difference Amplifier 1. Construct the circuit in Figure With VS adjusted to produce a 1 V peak sine wave at 1 khz, observe the output voltage VO (and VS to note the phase relationship) on an oscilloscope set to dc input coupling. 3. Sketch the output voltage waveform. Be sure to note the dc level in the output. 4. Exchange the 5 V dc power supply with the 1 V peak signal generator and vice versa. Repeat procedure step 2. Part 3 : Comparator and Schmitt Trigger 1. Construct the circuit in Figure 5 with the values of R1 and R2 obtained from your pre-lab. 2. Set the input voltage, VS to 8Vpk (sine wave) (or 16 Vpp) with a frequency of 1 khz and observe the output waveform on an oscilloscope. Use Vref = 5V. (Note: The input coupling of both channels should be set to DC) 3. Sketch the input, Vs and output voltage, VO in Table 1 (Note the level of VS at which the output voltage, VO changes level (VUTP and VLTP)) 4. Identify the transition points (VUTP and VLTP). 5. Compare your simulation with the experimental results 6. Repeat steps 2 & 3 with input voltage, VS values of 4V and 1V and record your results in Table1. 6

8 Table 1 V S = 8V V S = 4V V S = 1V V O and V I Transfer Curve 7

9 REFERENCES 1. Boylestad, R and Nashelsky. (2006). Electronic Devices and Circuit Theory, 9 th Edition, Prentice Hall. 2. Floyd, Thomas L. (2005). Electronic Devices, 7 th Edition, Prentice Hall. 3. Paynter, R.T. (2003). Introductory Electronic Devices and Circuits, 6 th Edition, Prentice Hall. 4. Neaman, D.A. (2001). Electronic Circuit Analysis and Design, 2 nd Edition, Mc Graw Hill. 5. Horenstein, M.N. (1996). Microelectronic Circuits and Devices, 2 nd Edition, Prentice Hall. 6. Fleeman, S.R. (1990). Electronic Devices Discrete and Intergrated, Prentice Hall. 8