Basic Electricity & Electronics IT 1011 for Second Semester Sample Question 1. Determine the forward voltage and forward current for the diode in figure for each of the diode models. Also find the voltage across the limiting resistor in each case. Assume r'd = 10 ohms. (10 marks) 2. Determinte the reverse voltage and reverse current for the diode in figure for each of the diode models. Also find the voltage across the limiting resistor in each case. Assume IR = 1 microAmpere. (10 marks) 3. Sketch the output voltage of each rectifier circuit for the indicated input voltages, as shown in fig. (a), (b) (10 marks) Figure (a) Fig (b) 4. Determine the peak and average power delivered to RL in figure 2.2. (10 marks) 5. Consider the circuit in figure. (10 marks) Figure 2.3 (a) What type of circuit is this? (b) What is the total peak secondary voltage? (c) Find the peak voltage across each half of the secondary. (d) Sketch the voltage wave form across RL. (e) What is the peak current through each diode? (f) What is the PIV for each diode? 6. Determine the output voltage for the bridge rectifier in figure. What PIV rating is required for the silicon diodes? The transformer is specified to have a 12 Vrms secondary voltage for the standard 110 V across the primary. (10 marks) 7.Determine the ripple faction for the filtered bridge rectifier in figure. (20 marks) 8.A 120 Hz full-wave rectified voltage with a peak value of 162 V is applied to the LC filter in figure. Determine the filter output in terms of its dc value and the rms ripple voltage. (20 marks) 9. A certain full-wave rectifier has a peak output voltage of 30V. A 50microF capacitor filter is connected to the rectifier. Calculate the peak-to-peak ripple and the dc output voltage developed across a 600 ohms load resistance. What is the percentage of ripple for that rectifier filter. (20 marks) 10.A certain zener diode has a ZZT = 6.8 V at IZT = 20 mA, and IZM = 50 mA. What is the voltage across the zener terminals when the current is 30 mA? When the current is 10 mA? (10 marks) IZ в€†l Z VZ + в€†l Z - + - VZ = VZT 11.Determine the minimum and the maximum input voltages that can be regulated by the zener diode in Figure. (20 marks) 12. Determine the minimum and the maximum load currents for which the zener diode in Figure will maintain regulation. What is the minimum RL the can be used? VZ = 12 V, IZK = 1mA and IZM = 50mA. Assume ZZ = 0 ohm and VZ remains a constant 12 V over the range of current values for simplicity. (20 marks) 13 .For the circuit in Figure. (20 marks) (a) Determine VOUT at IZK and at IZM. (b) Calculate the value of R that should be used. (c) Determine the minimum value of RL that can be used. 14.To what value must R be adjusted in figure to make IZ = 40mA? Assume VZ = 12 V at 30 mA and ZZ = 30 ohms. (20 marks) 15. A loaded zener regulator is shown in figure 3.5. VZ = 5.1 V at 35 mA, IZK = 1mA, ZZ = 12 ohms and IZM = 70mA. Determine the minimum and maximum permissible load currents. (20 marks) 16. State the mathematical relationship between О±DC and ОІDC. (20 marks) 17.Determine IB,IC,IE,VBE,VCE and VCB in the circuit of figure. The transistor has a ОІDC = 150. (20 marks) 18.Determine IB,IC,IE,VBE,VCE and VCB in figure for the following values: RB = 22kohm, RC = 220 ohms, VBB = 6V, VCC = 9V and ОІDC = 90. (20 marks) 19. Determine whether or not the transistor in figure is in saturation. Assume VCE(sat) = 0.2. (20 marks) 20. Determine whether or not the transistor in figure is saturated for the following values: ОІDC = 125, VBB = 1.5V, RB = 6.8kohms, VCE(sat) = 0.2, RC = 180 ohms, and VCC = 12 V. (20 marks) 21. The transistor in figure has the following maximum ratings: PD(max) = 800 mW, VCE(max) = 15V and IC(max) = 100mA. Determine the maximum value to which VCC can be adjusted without exceeding a rating which rating would be exceeded first? (20 marks) 22.Determine whether or not the transistor in figure are saturated. Assume VCE(sat) = 0.2. (20 marks) Basic Electricity & Electronics IT 1011 for Second Semester Sample Answer & Question 1. Determine the forward voltage and forward current for the diode in figure for each of the diode models. Also find the voltage across the limiting resistor in each case. Assume r'd = 10 ohms. (10 marks) Figure Solution: Complex model: IF = VBIAS в€’ 0.7 V 5V в€’ 0.7 V 4.3V = = 4.26mA = ' 1kв„¦ + 10в„¦ 1010в„¦ R LIMIT + rd VF = 0.7 V + I F rd' = 0.7 V + (4.26mA)(10в„¦) = 743mV VLIMIT = I F R LIMIT = (4.26mA)(1kв„¦) = 4.26V 2. Determinte the reverse voltage and reverse current for the diode in figure1. (b) for each of the diode models. Also find the voltage across the limiting resistor in each case. Assume IR = 1 microAmpere. (10 marks) Figure Solution: 3. Sketch the output voltage of each rectifier circuit for the indicated input voltages, as shown in fig. (a), (b) (10 marks) Figure (a) Fig (b) ). Solution: 3(b) Solution: 4.Determine the peak and average power delivered to RL in figure 2.2. (10 marks) Figure 2.2 Solution: 5.Consider the circuit in figure 2.3. (10 marks) Figure 2.3 (a) What type of circuit is this? (b) What is the total peak secondary voltage? (c) Find the peak voltage across each half of the secondary. (d) Sketch the voltage wave form across RL. (e) What is the peak current through each diode? (f) What is the PIV for each diode? Solution: Vp ( pri ) = 1.414Vrms = 1.414(110) = 155.54 (a) (b) This type of circuit is full-wave center-tapped rectifier. вЋ› N sec вЋћ вЋџвЋџVp( pri ) Vp(sec) = вЋњвЋњ вЋќ Npri вЋ 1 (155.4) =38.885 v 4 V sec 38.885 = = 19.4425v 2 2 = (c) (d) v (e) V sec - 0.7v 2 = 19.4425-0.7 Vp ( out ) = = 18.7425v Ipeak = (f) Vp(out ) 18.7425 = = 0.085A R 220 PIV = 2Vp(out) + 0.7v = 38.185v` 6. Determine the output voltage for the bridge rectifier in figure 2.4. What PIV rating is required for the silicon diodes? The transformer is specified to have a 12 Vrms secondary voltage for the standard 110 V across the primary. (10 marks) Figure Solution: The peak output voltage is Vp (sec) = 1.414 vrms = 1.414(12v) = 17v Vp(out) = Vp(sec) вЂ“ 1.4v = 17v-1.4v = 15.6v The PIV for each diode is PIV =Vp(out)+ 0.7v = 16.3v 7.Determine the ripple faction for the filtered bridge rectifier in figure 2.5. (20 marks) Figure The peak primary voltage is Vp(pri) = 1.414(115)v =163v The peak secondary voltage is 1 (163) = 16.3 Vp(sec) = 10 Vp(in) = Vp(sec) вЂ“ 1.4v = 14.9v VDC = (1- вЋЎ вЋ› вЋћвЋ¤ 1 1 вЋџвЋџвЋҐ 14.9 ) Vp(in) = вЋў1 в€’ вЋњвЋњ 2 fRLc вЋЈ вЋќ (240)(2.2)(50) вЋ вЋ¦ = (1-0.038)14.9v = 14.3v вЋ› 1 вЋћ вЋџвЋџ Vp(in) Vr = вЋњвЋњ вЋќ fRlc вЋ вЋЎ вЋ¤ 1 вЋў (120)(2.2)(50) вЋҐ (14.9) вЋЈ вЋ¦ = = 1.13v Vr r= V DC 1.13 14.3 = 0.079v = The percent ripple is 7.9%. 8.A 120 Hz full-wave rectified voltage with a peak value of 162 V is applied to the LC filter in figure. Determine the filter output in terms of its dc value and the rms ripple voltage. (20 marks) Figure Solution: . VDC(IN) = VAVG = 2V p ПЂ = 2(162) ПЂ = 103v Vr (in) = 0.308 Vp = 0.308 (162) = 49.9v VDC(OUT) Xl = 2 ПЂfl = Xc = вЋЎ вЋ¤ Rl вЋЎ1вЋ¤ вЋў вЋҐ VDC(IN) = вЋў вЋҐ вЋЈ1.1вЋ¦ вЋЈ ( Rw + Rl ) вЋ¦ = 2 ПЂ (120)(1000) = 754 (103) = 93.6v в„¦ 1 1 = 26.5 в„¦ = 2ПЂfc 2ПЂ (120)(50) вЋЎ Xl вЋ¤ вЋў вЋҐ Vr(in) вЋўвЋЈ X l в€’ X c вЋҐвЋ¦ вЋЎ 26.5 вЋ¤ = вЋў вЋҐ (49.9) вЋўвЋЈ 754 в€’ 26.5 вЋҐвЋ¦ = 1.82Vrms Vr(out) = 9. A certain full-wave rectifier has a peak output voltage of 30V. A 50microF capacitor filter is connected to the rectifier. Calculate the peak-to-peak ripple and the dc output voltage developed across a 600 ohms load resistance. What is the percentage of ripple for that rectifier filter. (20 marks) Solution: Vp (in) = 30v c = 50Вµf Rl 600 в„¦ = VDC = = вЋЎ вЋ› 1 вЋў1 в€’ вЋњвЋњ вЋЈвЋў вЋќ 2 fR вЋћвЋ¤ вЋџвЋҐ Vp(in) c вЋџвЋ вЋ¦вЋҐ вЋЎ вЋ› вЋћвЋ¤ 1 вЋџвЋџвЋҐ (30) вЋў1 в€’ вЋњвЋњ вЋЈ вЋќ 2(120)(600)(50) вЋ вЋ¦ = (1-0.138) 30 = 25.86v Vr вЋЎ 1 вЋ¤ вЋў вЋҐ Vp(in) fR c вЋЈ l вЋ¦ = вЋЎ вЋ¤ 1 = вЋў вЋҐ 30 вЋЈ (120)(600)(50) вЋ¦ = (0.277)30 = 8.33v r = Vr 8.33 = = 0.322v V DC 25.86 10.A certain zener diode has a ZZT = 6.8 V at IZT = 20 mA, and IZM = 50 mA. What is the voltage across the zener terminals when the current is 30 mA? When the current is 10 mA? (10 marks) IZ в€†l Z VZ + в€†l Z - + - VZ = VZT Solution: ZZT = 5в„¦, VZT = 6.8 V For I z = 30mA : The 30mA current is a 10mA increase above I ZT = 20mA . в€†I Z = I Z в€’ I ZT = +10mA в€†VZ = в€†I Z I ZT = (10mA)(5в„¦) в€’ +50mV VZ = 6.8V + в€†VZ = 6.8V + 50mV = 6.85V For I Z = 10mA : The 10mA current is 10 mA decrease below I ZT = 20mA в€†l Z = в€’10mA в€†VZ = в€†l Z Z ZT = (в€’10mA)(5в„¦) = в€’50mV VZ = 6.8V в€’ в€†VZ = 6.8V в€’ 50V = 6.75V 11.Determine the minimum and the maximum input voltages that can be regulated by the zener diode in Figure (20 marks) Figure Solution: VZ = 5.1V at IZT = 49mA, IZK = 1mA, and ZZ = 7в„¦ at IZT. The equivalent circuit is shown in figure. At IZK = 1mA, the output voltage is VOUT = 5.1V - в€†VZ вЂ“ 5.1V вЂ“ (IZT_IZK) ZZ = 5.1V вЂ“ (48mA) ( 7в„¦) = 5.1V вЂ“ 0.336V = 4.76V Therefore, VIN(min) = IZK R + VOUT = (1mA)(100 в„¦) + 4.76V = 4.86V IZM = PD(max) / VZ = 1W/5.1V = 196mA VOUT = 5.1V+ в€†VZ = 5.1V + (IZM - IZT) ZZ = 5.1V + (147mA) (7в„¦) = 5.1V + 1.03V = 6.13V VIN(max) = IZMR + VOUT = (196mA)(100 в„¦) + 6.13V = 25.7 V 12. Determine the minimum and the maximum load currents for which the zener diode in Figure will maintain regulation. What is the minimum RL the can be used? VZ = 12 V, IZK = 1mA and IZM = 50mA. Assume ZZ = 0 ohm and VZ remains a constant 12 V over the range of current values for simplicity. (20 marks) Figure Solution: When I L = 0A ( R L = О± ) I Z (max) = I T = (VIN в€’ VZ ) / R = (24V в€’ 12V)470в„¦ = 25.5mA I L (max) = 0A When R L (min) в‡’ I L = I T в€’ I ZK = 25.5mA в€’ 1mA = 24.5mA R L (min) = VZ / I L (max) = 12V / 24.5mA = 490в„¦ 13 .For the circuit in Figure. (a) Determine VOUT at IZK and at IZM. (b) Calculate the value of R that should be used. (20 marks) (c) Determine the minimum value of RL that can be used. Figure Solution: (a) FOR IZK: (b) (c) VOUT = VZ = 15V -в€†IZ ZZT = 15V вЂ“(IZT-IZK )ZZT = 15V вЂ“ (16.75mA) (14в„¦) = 15V вЂ“ 0.235V = 14.76V IZM = PD(max) / VZ = 1W / 15V =66.7mA For IZM: VOUT = VZ = 15V + в€†IZIZZT = 15V + (IZM - IZT) ZZT = 15V + (49.7mA)(14 в„¦) R = (VIN- VZ ) / IZM = (24V вЂ“ 15.7V) / 66.7V = 124 в„¦ R = 130 в„¦ IT = (VIN вЂ“ VOUT) / R = (24V вЂ“ 14.7V) / 130 в„¦ = 71.0mA IL = IT вЂ“IZK = 71.0mA вЂ“ 0.25mA RL(min) = VOUT / IL = 14.76V / 70.75mA = 209 в„¦ (a) (b) 14.To what value must R be adjusted in figure to make IZ = 40mA? Assume VZ = 12 V at 30 mA and ZZ = 30 ohms. (20 marks) Figure Solution: в€†Iz = 40-30 = 10mA в€†Vz = в€†Iz Zz = 10(30mA) = 0.3v Vz = 12+ в€†Vz = 12+0.3 = 12v R= Vin в€’ V z 18 в€’ 12.3 = = 142.5v I 40mA 15. A loaded zener regulator is shown in figure. VZ = 5.1 V at 35 mA, IZK = 1mA, ZZ = 12 ohms and IZM = 70mA. Determine the minimum and maximum permissible load currents. (20 marks) Figure Solution: When Rl = в€ћ , Iz (max) = It = Vinв€’V z R 8 в€’ 5.1 = 22 = 0.131A I L (min) = 0A When R L (min) в‡’ I L (max) = I T в€’ I ZK = 0.131 вЂ“ 1 mA = 0.1308 A 16. State the mathematical relationship between О±DC and ОІDC. (20 marks) Solution: 17.Determine IB,IC,IE,VBE,VCE and VCB in the circuit of figure 4.1. The transistor has a ОІDC = 150. (20 marks) Figure Solution: 18.Determine IB,IC,IE,VBE,VCE and VCB in figure for the following values: RB = 22kohm, RC = 220 ohms, VBB = 6V, VCC = 9V and ОІDC = 90. (20 marks) Figure Solution: 19. Determine whether or not the transistor in figure is in saturation. Assume VCE(sat) = 0.2. (20 marks) Figure Solution: 20. Determine whether or not the transistor in figureis saturated for the following values: ОІDC = 125, VBB = 1.5V, RB = 6.8kohms, VCE(sat) = 0.2, RC = 180 ohms, and VCC = 12 V. (20 marks) Figure Solution: IC (sat) = VCC вЂ“ VCE (sat) = 12 вЂ“ 0.2 = 0.065 A RC 18 IB = VBB вЂ“ VBE = 1.5 вЂ“ 0.7 = 1.176 x 10-4A RB 6.8k в„¦ IC = ОІDC вЂ“ IB = 1258 x 1.176x 10-4 = 0.014A Therefore, IC < IC (sat) Therefore, transistor is not saturated. 21. The transistor in figure has the following maximum ratings: PD(max) = 800 mW, VCE(max) = 15V and IC(max) = 100mA. Determine the maximum value to which VCC can be adjusted without exceeding a rating which rating would be exceeded first? (20 marks) Figure Solution: IB = (VBB - VBE) / RB = (5V вЂ“ 0.7V) / 22kв„¦ = 195 ВµA IC = ОІDC IB = (100)(195 ВµA) = 19.5 mA VRC = IC RC = (19.5mA)(1kв„¦) = 19.5 V When VCE = VCE (max) = 15V VRC = VCC вЂ“ VCE VCC (max) = VCE (max) + VRC = 15V + 19.5V = 34.5V PD = VCE (max) IC = (15V)(19.5mA) = 293mW If the base current is removed causing the transistor to turn off, VCE (max) = VCC = 34.5V 22.Determine whether or not the transistor in figure are saturated. Assume VCE(sat) = 0.2. (20 marks) Figure Solution: IC(sat) = VCC вЂ“ VCE (sat) = 15 вЂ“ 0.2 = 0.082 A RC 180 IB = VBB вЂ“ VBE = 5 вЂ“ 0.7 = 1.102mA RB 3.9k в„¦ IC = ОІDC IB = 50 x 1.102 mA = 0.055 mA Therefore, IC < IC (sat) Therefore, transistor is not saturated. Introduction to Computer System IT 1012 Sample Question for Second semester 1. Write a program that determines whether a given integer is even or add. (10 marks) 2. Create a program that test whether a given integer is zero or positive or negative. (10 marks) 3. Write a program that test on exam mark is pass, pass with Distinction or fail. (10 marks) 4. Write a program that will input numbers and find the maximum number and minimum numbers. (10 marks) 5. Write a program to sort the three integers a, b and c in ascending order. The number will be given from the keyboard. (10 marks) 6. Write a program to input two numbers and then display the following menu: Вѓ Sum of two numbers Вѓ Subtract the second number from the first Вѓ Multiply the two numbers by the second Вѓ Divide the two numbers by the second Вѓ None of the above The program will then produce the output selected by the user from the menu. (20 marks) 7. Write an appropriate control structure that will examine the value of a following point variable called temp and print one of the following messages, depending on the value assigned to temp. (10 marks) (a) ICE, if the value of temp is less than 0. (b) WATER, if the value of temp lies between 0 and 100, (c) STEAM, if the value of temp exceeds 100. 8. Write a program that reads a grade A, B, C, D or F and then print вЂњExcellentвЂќ, вЂњGoodвЂќ, вЂњFairвЂќ, вЂњPoorвЂќ, and вЂњFailвЂќ. (10 marks) 9. Write a program to calculate the sum of the given ten integers and then display the result. Ask the user to input ten integers. (5 marks) 10. Write a program to calculate the sum and average value of the given integers. (by while loop) (10 marks) 11. Write a program to calculate the sum and average value of the given integers. (by do while loop) (10 marks) 12. Write a program to find and display the sum of the successive even integers 2, 4, вЂ¦ 200. (5 marks) 13. Write a program to find and display the sum of the successive add integers 1, 3, вЂ¦.. 199. (5 marks) 14. Write a program to find the sum of the following series. (5 marks) 7, 11, 15, 19, 23, 31, 35, 39, 43. 15. Write a program to find the factorial value for a given number n ! = 1*2*3* ... *n (10 marks) 16. Suppose you deposit $ 50 per month in blank account every month for a year. Every month, after the deposit has been made interest at the rate of 1 % is added to the balance. Eg. After one month, the balance is $ 50.5, and after two month it is $ 101.51. Write a program to calculate the balance for one year. (10 marks) 17. Ten students in a class write a test. Three subject marks enter as input data for each student. Write a program which will read all ten students marks from the keyboard and determine the result as follow. (20 marks) Roll No. Subject 1 Subject 2 Subject 3 Total Remark 1 67 85 70 222 Pass with Credit 2 35 68 59 162 Fail 3 70 60 57 187 Pass . . . . . . . . . . . . . . . . . . 10 67 75 65 207 Pass 18. Create a function to calculate the sum and product of the given two integers. Write a program to implement function. (10 marks) 19. Write a function to calculate the area of a room. Ask the user to enter the length and width of the room. (10 marks) 20.Write a function to calculate tax amount from the amount of purchase. Ask the user to enter the amount of purchase and then call tax (float) function to calculate tax and then display the amount of purchase, amount of tax and total amount. Use tax rate = 0.065. (10 marks) 21. Write the functions to calculate the following equations. x cos (a) + y sin (a) , - x sin (a) + y cos (a) (20 marks) 22. Write your own function double Mypow (double a, double b); to return the value of ab, calculated as exp ( b * log (a) ) Try it out in a test program (remember to include math.h) (10 marks) 23. Write your own C++ function to compute the exponential function directly from the Tayler series: (20 marks) ex + 1 + x + n2 / 2! + n3 / 3! + --24. Write a function Bin (int n, int r) which returns the binomial coefficient n! / (r!(r-n)! ). (20 marks) 25. Write a function to find the Fibonacci numbers are generated by the sequence 1, 1, 2, 3, 5, 8, 13, вЂ¦. (20 marks) 26. Write a program to perform the following: (20 marks) - Accept three numbers - Calculate average - Find smallest and largest numbers - Display the results such as average, maximum, and minimum. 27. Write a program or function the max: number of the 10 integers. (20 marks) 28. Write some statements to put some Fibonacci numbers (1, 2, 3, 5, 8, 13, вЂ¦) int an array F[0],вЂ¦. What is the largest one which can be represented exactly? (10 marks) 29. Salary level at any educational institution are (in thousand of dollars) 9, 10, 12, 15, 20, 35 and 50. The numbers of employees at each level are respectively, 3000, 2500, 1500, 1000, 400, 100, 25. Write a program which finds and writes. (a) the average salary level; (b) the number of employees above and below the average level, (c) the average salary earned by an individual in the institution. (20 marks) 30. Write a program which finds the mean of the elements of an array, and the element of the array furthest in absolute value from the mean. Eg. If the array elements are -4, 0, 5, 1, 10, 3, 4, 1, 2, 4 The element 10 is furthest from the mean. (20 marks) 31. Write a program to sort the n integers by using exchange sort method. (20 marks) 32. Write a program to sort the n integers by using bubble sort method. (By using ascending order) (20 marks) 33. List an integer array with n elements. By using linear search, write a program to search a number in that array. Display вЂњFoundвЂќ if the search number is found or display вЂњNot foundвЂќ if the search number is not found. (20 marks) 34. List an integers array with n elements and write a program to search a number in that array by using binary search method. Display a вЂњFoundвЂќ if the search number is found or display вЂњNot foundвЂќ if it is not found. (20 marks) Introduction to Computer System IT 1012 Sample Answer and Question for Second semester 2 1. Write a program that determines whether a given integer is even or add.(10 marks) Answer # include <iostream.h> void main ( ) { int num; cout << вЂњEnter a numberвЂќ; cin >> num; if (num % 2 == 0 ) cout << вЂњEnter numberвЂќ; else cout << вЂњOdd numberвЂќ; } 2. Create a program that test whether a given integer is zero or positive or negative. (10 marks) Answer # include <iostream.h> void main ( ) { int num; cout << вЂњEnter a numberвЂќ; cin >> num; if (num <0) cout <<вЂќNegativeвЂќ; else if (num >0) cout << вЂњPositiveвЂќ; else cout << вЂњZeroвЂќ; } 3. Write a program that test on exam mark is pass, pass with Distinction or fail. (10 marks) Answer #include<iostream.h> void main() { int x; cout<<вЂќEnter three exam markвЂќ; cin>>x>>y>>z; if(x>=40&& y>=40&& z>=40) { if(x>=80&& y>=80&& z>=80) cout<<вЂќpass with DistinctionвЂќ; else if(x>=65&& y>=65&& z>=65) cout<<вЂќpass with CreditвЂќ; else cout<<вЂќPassвЂќ; } else cout<<вЂќfailвЂќ; getch(); } 3 4. Write a program that will input numbers and find the maximum number and minimum numbers. (10 marks) Answer # include <iostream.h> void main ( ) { int x, y; cout << вЂњEnter two numberвЂќ; cin << x >> y; if ( x > y ) cout << x << вЂњis maxвЂќ << y << вЂњis minвЂќ; else cout << y << вЂњis maxвЂќ << x << вЂњis minвЂќ; } 5. Write a program to sort the three integers a, b and c in ascending order. The number will be given from the keyboard. (10 marks) Answer # include <iostream.h> void main ( ) { int a, b, c, max, mid, min; cout << вЂњEnter three numbersвЂќ; cin >> a >> b >> c; if (a > b && a > c) { max = a; if (b>c) { mid = b; min = c; } else { mid = c min = b } } else if (b > a && b > c) { max = b; if (a > c) { mid = a; min = c; } else { mid = c; min = a; } } else { max = c; if (a > b) 4 { mid =a; min = b; } else { mid = b; min = a; } } cout << min << вЂњ\tвЂќ << mid << вЂњ\tвЂќ << max; } 6. Write a program to input two numbers and then display the following menu: Вѓ Sum of two numbers Вѓ Subtract the second number from the first Вѓ Multiply the two numbers by the second Вѓ Divide the two numbers by the second Вѓ None of the above The program will then produce the output selected by the user from the menu. (20 marks) Anwer #include <iostream.h> void main { int a, b, x; cout << вЂњEnter two numbersвЂќ; cin << a >> b; cout << вЂњ 1. Sum of two numbersвЂќ; 2. Subtract the second number from the first \n 3. Multiply the two numbers by the second \n 4. Divided the two numbers by the second \n 5. None of the aboveвЂќ cout << вЂњEnter select numberвЂќ; cin >> x ; Switch (x) { case 1: cout << вЂњSum =вЂќ << a + b; break; case 2: cout << вЂњSubtract =вЂќ << a вЂ“ b; break; case 3: cout << вЂњMultiply =вЂќ << a * b; break; case 4: cout << вЂњDivide =вЂќ << a/b ; break; default: cout << вЂњcout << вЂњNone of aboveвЂќ; } } 7. Write an appropriate control structure that will examine the value of a following point variable called temp and print one of the following messages, depending on the value assigned to temp. (10 marks) (a) ICE, if the value of temp is less than 0. (b) WATER, if the value of temp lies between 0 and 100, (c) STEAM, if the value of temp exceeds 100. 5 Answer # include <iostream.h> voice main ( ) { float temp; cout << вЂњEnter temperatureвЂќ; cin >> temp; if (temp < 0) cout << вЂњICEвЂќ; else if (temp >= 0 && temp <= 100) cout << вЂњWATERвЂќ; else cout <<вЂќSTREAMвЂќ; } 8. Write a program that reads a grade A, B, C, D or F and then print вЂњExcellentвЂќ, вЂњGoodвЂќ, вЂњFairвЂќ, вЂњPoorвЂќ, and вЂњFailвЂќ. (10 marks) Answer # include <iostream.h> void main ( ) { char ch ; cout << вЂњEnter A, B, C, D or FвЂќ; cin >> ch; switch ( toupper (ch) ) { case вЂ�AвЂ™ : cout << вЂњExcellentвЂќ; break; case вЂ�BвЂ™ : cout << вЂњGoodвЂќ; break; case вЂ�CвЂ™ : cout << вЂњFairвЂќ; break; case вЂ�DвЂ™ : cout вЂњPoorвЂќ; break; case вЂ�FвЂ™ : cout << вЂњFailвЂќ; break; default : cout << вЂњInvalid characterвЂќ; } } 9. Write a program to calculate the sum of the given ten integers and then display the result. Ask the user to input ten integers. (5 marks) Answer # include <iostream.h> void man ( ) { int i, num, sum = 0 ; for ( i = 0; i < 10 ; i++ ) { cout << вЂњEnter a numberвЂќ; cin >> num; sum += num; } cout << вЂњ\n The sum isвЂќ << sum; } 6 10. Write a program to calculate the sum and average value of the given integers. (by while loop) (10 marks) Answer # include <stdio.h> # include <conio.h> void main ( ) { int i = 0, sum = 0, num; float avg; cout << вЂњEnter the numberвЂќ; cin >> num; while (num пЂЎ! = 0) { i++ sum += num; cout << вЂњEnter numberвЂќ; cin >> num; } avg = sum / i ; cout << вЂњThe sum isвЂќ << sum; cout << вЂњThe average isвЂќ << avg; } 11. Write a program to calculate the sum and average value of the given integers. (by do while loop) (10 marks) Answer # include <iostream.h> # include <conio.h> void main ( ) { int i = 0, sum = 0, num; float avg; do { cout << вЂњEnter the numberвЂќ; cin >> num; i++ ; } while (I < 5) avg = sum / 5 ; cout << вЂњThe sum isвЂќ << sum; cout << вЂњThe average isвЂќ << avg; } 12. Write a program to find and display the sum of the successive even integers 2, 4, вЂ¦ 200. (5 marks) Answer # include <iostream.h> # include <conio.h> void main ( ) 7 { int i, sum = 0; clrscr ( ); for ( i = 2; i <= 200; i+ = 2) sum = sum + i ; cout << вЂњsum =вЂќ << sum; getch ( ); } 13. Write a program to find and display the sum of the successive add integers 1, 3, вЂ¦.. 199. (5 marks) Answer # include <iostream.h> # include <conio.h> void main ( ) { int i, sum = 0; clrscr ( ); for ( i = 1; i <= 199; i += 2 ) sum = sum =+ i; cout << вЂњSum =вЂќ << sum; getch ( ); } 14. Write a program to find the sum of the following series. 7, 11, 15, 19, 23, 31, 35, 39, 43. (5 marks) Answer # include <iostream.h> # include <conio.h> void main ( ) { int i, sum = 0; clrscr ( ); for (i = 1; i <= 10; i++ ) sum = sum + ( (i*4) + 3 ); cout << вЂњSum =вЂќ << sum; getch ( ); } 15. Write a program to find the factorial value for a given number n ! = 1*2*3* ... *n Answer # include <iostream.h> void main ( ) { int n, f = i ; cout << вЂњEnter factorial numberвЂќ; cin >> n; for ( i = 1; i <= n; i++ ) { f *= i ; } cout <<n << вЂњ! =вЂќ << f; } (10 marks) 8 16. Suppose you deposit $ 50 per month in blank account every month for a year. Every month, after the deposit has been made interest at the rate of 1 % is added to the balance. Eg. After one month, the balance is $ 50.5, and after two month it is $ 101.51. Write a program to calculate the balance for one year. (10 marks) # include <iostream.h> void main ( ) { int i ; float balance = 0 ; interest ; cout << вЂњmonth \t balance \nвЂќ; for ( i = 1; i<= 12; i++ ) { balance += 50; interest = (balance * 1) / 100; balance += interest; cout << 1 << вЂњ\tвЂќ << balance << вЂњ\nвЂќ; } } 17. Ten students in a class write a test. Three subject marks enter as input data for each student. Write a program which will read all ten students marks from the keyboard and determine the result as follow. (20 marks) Roll No. Subject 1 Subject 2 Subject 3 Total Remark Pass with Credit 222 70 85 67 1 Fail 162 59 68 35 2 Pass 187 57 60 70 3 . . . . . . . . . . . . . . . . . . Pass 207 65 75 67 10 Answer # include <iostream.h> void main ( ) { int i; m1, m2, m3; cout << вЂњRoll no \t sub 1 \t sub 2 \t sub 3 \t total \t remark \nвЂќ; for ( i = 1; i <=10; i ++ ) { cout << вЂњEnter Students MarksвЂќ; cin >> m1 >> m2 >>m3; cout << i << вЂњ\tвЂќ << m1 << вЂњ\tвЂќ << m2 << вЂњ\tвЂќ << m3 << вЂ�\tвЂќ << (m1+m2+m3) << вЂњ\tвЂќ; if ( m1 > 65 && m2 > 65 && m3 > 65 ) cout << вЂњPass with credit \nвЂќ; else if ( m1 >= 50 && m2 >= 50 && m3 >= 50 ) cout << вЂњPass \nвЂќ; else cout << вЂњFail \nвЂќ; } } 9 18. Create a function to calculate the sum and product of the given two integers. Write a program to implement function.(10 marks) Answer # include <iostream.h> int sum (int x, int y); int mul (intx, int y); void main ( ) { int a, b; cout << вЂњEnter Two NumberвЂќ; cin >> a >> b; cout << вЂњSum =вЂќ << (a, b); cout << вЂњMul + вЂњ << (a, b); } int sum (int x, int y) { int z; z = x + y; return z; } int Mul (intx, int y) { int h; h = x * y; return h; } 19. Write a function to calculate the area of a room. Ask the user to enter the length and width of the room. (10 marks) Answer # include <iostream.h> int area (int x, int y); void main ( ) { int l, h, A; cout << вЂњEnter length and wideвЂќ; cin >> l >> h; A = area (l, b); cout << вЂњArea =вЂќ << A; } { int area (int x, int y) return (x * y); } 10 20.Write a function to calculate tax amount from the amount of purchase. Ask the user to enter the amount of purchase and then call tax (float) function to calculate tax and then display the amount of purchase, amount of tax and total amount. Use tax rate = 0.065. (10 marks) Answer # include <iostream.h> float tax (float P); void main ( ) { float P; cout << вЂњEnter purchaseвЂќ; cin >> P; float t = tax (p); cout << вЂњPurchase =вЂќ << P; cout << вЂњTax =вЂќ << t; cout << вЂњTotal =вЂќ << (p + t); } float tax (float P) { return (0.065 * P); } 21. Write the functions to calculate the following equations. x cos (a) + y sin (a) , - x sin (a) + y cos (a) Answer # include <iostream.h> # include <math.h> # include <conio.h> double Xnew (double, double, double); double Ynew (double, double, double); void main ( ) { double a, x, y; cout << вЂњEnter a, x, yвЂќ; cin >> a >> x >> y; cout << вЂњXnewвЂќ << Xnew (x, y, a) << endl; cout << вЂњYnewвЂќ << Ynew (x, y, a); getch ( ); } double Xnew (double x, double y, double a) { return (x * cos (a) + y * sin (a) ); } double Ynew (double x, double y, double a) { return (-x * sin (a) + y * cos (a) ); } (20 marks) 11 22. Write your own function double Mypow (double a, double b); to return the value of ab, calculated as exp ( b * log (a) ) Try it out in a test program (remember to include math.h) (10 marks) (10 marks) # include <iostream.h> double Mypow (double a, double b); void main ( ) { double a, b; cout << вЂњEnter a & bвЂќ; cin >> a >> b; cout << вЂњMypow =вЂќ << Mypow (a, b); } double Mypow (double a, double b) { return exp ( b * log (a) ); } 23. Write your own C++ function to compute the exponential function directly from the Tayler series: ex + 1 + x + n2 / 2! + n3 / 3! + --(20 marks) Answer # include <iostream.h> double Myexp (double n); void main ( ) { double x; cout <<вЂќEnter xвЂќ; cin >> x; cout << вЂњMyexp =вЂќ << Myexp (x); } double Myexp (double x) { double e = 1, d = 1, p = 1, f = 1, i = 1; while ( d > 0.00001) { p *= x; f *= I; i++ ; d = p/f; e += d; } return exp; } 24. Write a function Bin (int n, int r) which returns the binomial coefficient n! / (r!(r-n)! ). (20 marks) 12 Answer # include <iostream.h> double Bin (int n, int r); int facto (int x); void main ( ) { int n, r; cout << вЂњEnter n & rвЂќ; cin >> n >> r; cout << Bin } double Bin (int n, int r) { double res; res = (double) facto (n) / (facto (n) * facto (n вЂ“ r) ); return res; } int facto (int x) { int f = 1; for (i = 1;i <= x ; i++ ) { f *= I; } return f; } 25. Write a function to find the Fibonacci numbers are generated by the sequence 1, 1, 2, 3, 5, 8, 13, вЂ¦. (20 marks) Answer # include <iostream.h> void fibo (int n); void main ( ) { int n; cout << вЂњEnter How many numbersвЂќ; cin >> n; fibo (n); } void fibe (int n) { int f = 1, s = 1, t, n, I; cout << f << вЂњ\tвЂќ << s << вЂњ\TвЂќ ; for ( I = 3; I <= n; i++ { t = f + s; cout << t << вЂњ\tвЂќ; f = s; s = t; } } 13 26. Write a program to perform the following: - Accept three numbers - Calculate average - Find smallest and largest numbers - Display the results such as average, maximum, and minimum. Answer # include <iostream.h> int a, b, c; void accept ( ); float avg (int x, int y, int z); int min (int x, int y, int z); int max (int x, int y, int z); void display (float avg, int min, int max); void main ( ) { float A; int B, C; accept ( ); A = avg (a, b, c); B = min ( a, b, c); C = max (a, b, c); Display (A, B, C); } void accept ( ) { cout << вЂњEnter three numbersвЂќ; cin >> a >> b >> c; } float avg (int x, int y, int z) return (x = y + z) / 3.0 ; } { int min (int x, int y, int z) { int m; m = x; if (m > y) m = y; if (m > z) m = z; return m; } void display (float avg, int min, int max) { cout << вЂњAvg =вЂќ << avg; cout << вЂњmin =вЂќ << min; cout << вЂњmax =вЂќ << max; } (20 marks) 14 27. Write a program or function the max: number of the 10 integers. (20 marks) Answer # include < stdio. h> # include < conio. h> # define MAXINT - 32768 void maximum (int n, int* cmax); void main ( ) { int i , num , max; printf ( вЂњPlease enter 10 integers \nвЂ™вЂ™); max= MAXANT; for ( i=0; i<10; i+1) { Scanf (вЂњ % dвЂќ , & num); maximum (num, &max); } Printf (вЂњ \n The maximum number entered was %d\n, max); getch ( ); } Void maximum ( int n, int* cmax ) { if ( n> * cmax ) * cmax = n; } 28. Write some statements to put some Fibonacci numbers (1, 2, 3, 5, 8, 13, вЂ¦) int an array F[0],вЂ¦. What is the largest one which can be represented exactly? (10 marks) Answer # include < iostream .h > void main ( ) { int f [100] = {1,1}; int I; cout << вЂњ How many Fibonacci numberвЂ™вЂ™ ; cin >> n; for ( i=0 ; i<n-2; i++ ) { f[i+2] = f[i]+ f[i+1]; } Cout << вЂњthe largest numвЂќ << f(n-1) ; } 15 29. Salary level at any educational institution are (in thousand of dollars) 9, 10, 12, 15, 20, 35 and 50. The numbers of employees at each level are respectively, 3000, 2500, 1500, 1000, 400, 100, 25. Write a program which finds and writes. (20 marks) (a) the average salary level; (b) the number of employees above and below the average level, (c) the average salary earned by an individual in the institution. Answer # include <iostream.h> void main ( ) { int I, total salary = 0, below + 0, above = 0, total = 0, total emp = o; float avg salary , avg; int s [7] = { 9, 10, 12, 15, 20, 35, 50 }; int e [7] = { 3000, 2500, 1500, 1000, 400, 100, 25}; for (i = 0; i < 7; i++ ) { total salary += s [i]; } avg salary = total salary / 7.0; for ( i= 0; I < 7; i++ ) { if ( s [i] < avg salary ) below += e [i]; else above += e [i]; } for ( i= 0; i < 7; i++ ) { total += s [i] * e [i]; total emp = e [i]; } avg = (float) total / total emp ; cout << вЂњavg salary =вЂќ << avg salary; cout << вЂњthe number of employees below level =вЂќ << below; cout << вЂњthe number of employees above level =вЂќ << above; cout << вЂњindividual avgвЂќ << avg; } 30. Write a program which finds the mean of the elements of an array, and the element of the array furthest in absolute value from the mean. Eg. If the array elements are -4, 0, 5, -1, 10, 3, 4, 1, 2, 4 The element 10 is furthest from the mean. (20 marks) Answer # include <iostream.h> # include < math.h> void main ( ) { int I, float d, f, sum = 0; float mean; int A [10] = { -4, 0, 5, -1, 10, 3, 4, 1, 2, 4}; for ( i = 0; i < 10; i++ ) { if (d < fabs (mean вЂ“ A [i]) ) { d = fabs (mean вЂ“ A [1]) ); f = A [i]; } } cout << вЂњfarthest =вЂќ << f; 16 cout << вЂњabs value =вЂќ << mean; } 31. Write a program to sort the n integers by using exchange sort method. (20 marks) Answer # include <iostream.h> void sel-sort (int B [ }, int n); void main ( ) { int A [100], n; cout << вЂњHow many sorting numberвЂќ; cin >> n; for (i = 0; i < n, i++ ) { cout << вЂњEnter numbersвЂќ; cin >> A [i]; } sel-sort (A, n); for (i = 0; i < n; i++ ) { cout << A [i]; } void sel-sort (int B [ ], int n) { int i, j, temp, min, p; for ( i = 0; i < n вЂ“ 1; i++ ) { min = B [i]; p = i; for ( j = i+ 1; j < n; j++ ) { if (min > B [j] ) { min = B [j]; p = j; } } temp = B [i]; B [i] = B [p]; B [p] = temp; } } 32. Write a program to sort the n integers by using bubble sort method. (By using ascending order) Answer # include <iostream.h> void bub-sort (int A [ ], int n); void main ( ) { int A [100], n; (20 marks) 17 cout << вЂњHow many sorting numbersвЂќ; cin >> n; for ( i = 0; i < n; i++ ) { cout << вЂњEnter numbersвЂќ; cin >> A [i}; } bub-sort (A, n); for ( i = 0; i < n; i++ ) { cout << A [i]; } } void bub-sort (int A [ ], int n ) { int x, temp, l; x = n; while ( x > 0 ) { l = 0; for ( i = 0; i < x вЂ“ 1; i++ ) { if ( A [i] > A [ i + 1] ) { temp = A [i]; A [i] = A [ I + 1]; A [ i + 1] = temp; l =i + 1; } } x = 1; } } 33. List an integer array with n elements. By using linear search, write a program to search a number in that array. Display вЂњFoundвЂќ if the search number is found or display вЂњNot foundвЂќ if the search number is not found. (20 marks) Answer # include <iostream.h> void main ( ) { int A [100], n, num, found = 0; cout << вЂњHow many numbersвЂќ cin >> n; for (int i = 0;i < n; i++ ) { cout << вЂњEnter numberвЂќ; cin >> A [i]; } cout << вЂњEnter search numberвЂќ; cin >> num; 18 i=0 while (i < && ! found ) { if ( num == A [i] ) found = 1; else i++ ; } if (found) cout << вЂњFoundвЂќ; else cout << вЂњNot FoundвЂќ; } 34. List an integers array with n elements and write a program to search a number in that array by using binary search method. Display a вЂњFoundвЂќ if the search number is found or display вЂњNot foundвЂќ if it is not found. (20 marks) Answer # include <iostream.h> void main ( ) { int A [100], num, n, f, l, M; cout << вЂњEnter how many numbersвЂќ; cin >> n; for ( i = 0; i < n; i++ ) { cout << вЂњEnter search numberвЂќ; cin >> num; f = 0; l = n вЂ“ 1; while ( f <= 1 && !found ) { M = (f + i )/ 2 ; if ( num == A [M] ) found = 1; else if ( num > A [M] ) f = M + 1; else l = M вЂ“ 1; } if (found) cout << вЂњFoundвЂќ; else cout << вЂњNot FoundвЂќ; } Digital Electronic IT 1013 for Second Semester Sample Question 1. Explain full adder and draw a complete logic circuit of it. (20 marks) 2. Use 74HC85 comparators to compare the magnitudes of two 8-bits numbers. Show the comparators with proper interconnections. (10 marks) 3. What is multiplexers and draw a logic diagram for 4-inputs multiplexers.(20 marks) 4. (a) Convert the binary number 0101 to Gray code with exclusive- OR gates.(10 marks) (b) Convert the Gray code 1011 to binary with exclusive- OR gates.(10 marks) 5. Implement the logic function specified in table by using a 74LS151 8-input data selector/multiplexer. Compare this method with discrete logic gate implementation. (10 marks) Inputs Output A2 A1 A0 Y 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 1 1 1 1 0 6. (a) Draw the logic diagram for a 1-line-to-4-line demultiplexer.(10 marks) (b) The serial data input waveform (Data in) and data-select inputs (S0 and S1) are shown in figure. Determine the data-output waveform on D0 trough D3 for the demultiplexer.(10 marks) Data in S0 S1 7. (a) Determine the Q output waveform if the inputs shown in figure are applied to a gated S-R latch that is initially RESET. (b)Determine the Q output waveform if the inputs shown in figure are applied to a gated D latch, which is initially RESET. (20 marks) S R EN 8. Determine the Q and Q output waveform of the flip-flop in figure for the S, R and CLK input in figure. Assume that the positive edge-triggered flip-flop is initially RESET. (10 marks) CLK 1 2 3 4 5 6 CLK S Q S C R o R 9. The waveform in figure are applied to the J, K and clock inputs are indicated. Determine the Q output, assuming that the flip-flop is initially RESET. (10 marks) 10. For the positive edge-triggered J-K flip-flop with preset and clear input in figure, determine the Q output for the inputs shown in the timing diagram in part (a) if Q is initially LOW.(10 marks) Q 1 2 3 4 5 6 7 8 9 CLK PRE CLR HIGH PRE o Q J C o R Q o CLR 11. (a) A certain application requires a one-shot with a pulse width of approximately 100ms. Using 74121 show the connections and the component values. (b) Determine the values of REXT and CEXT that will produce a pulse width of 1 Вµs when connected to a 74LS122. (20 marks) 12.(a) What is the output width for a 555 mono stable circuit with R1=2.2 kв„¦ and C1=0.01ВµF? (b) A 555 timer configured to run in the as table mode (oscillator) is shown in figure. Determine the frequency of the output and duty cycle. (10 marks) 13. A 4-bit asynchronous binary counter is shown in figure. Each flip-flop is negative edge-triggered and has a propagation delay for 10ns. Develop a timing diagram showing the Q output of each flip-flop and determine the total propagation delay time from the triggering edge of a clock pulse until a corresponding change can occur in the which the counter can be operated. (10 marks) 14. Show how an asynchronous counter can be implemented having modulus of twelve with a straight binary sequence from 0000 though 1011. (20 marks) 15. Design a counter with the irregular binary count sequence in the state diagram of figure. Use J-K flip-flops.(30 marks) 001 (1) 010 (2) 111 (7) 101 (5) 16. Develop a synchronous 3-bit UP/DOWN counter with a Gray code sequence. The counter should count up when an UP/ control input is 1 and count down when the control input is 0. (30 marks) 17. Design a binary counter with the sequence shown in the state diagram of figure. (20 marks) 0 3 11 9 5 7 18. Use 74LS160 counters to obtain a 10KHz waveform from a 1MHz clock. Show the logic diagram. (10 marks) 19. Implement the decoding of binary state 2 and binary state 7 of a 3-bit synchronous counter. Show the entire counter timing diagram and the output waveforms of the decoding gates. Binary 2 = 2Q1 0 and binary 7 = Q2Q1Q0 .(20 marks) 20. Determine the overall modulus of the two cascaded counter configurations in figure. (10 marks) Input Input CTR DIV 8 CTR DIV 12 CTR DIV 10 CTR DIV 4 CTR DIV 16 CTR DIV 7 Output CTR DIV 5 Output Digital Electronic IT 1013 for Second Semester Sample Answer & Question 1 1. Explain full adder and draw a complete logic circuit of it.(20 marks) Answer The full-adder accepts two input bits and an input carry and generates a sum output and an output carry. Truth Table for full-adder A 0 0 0 0 1 1 1 1 A B B 0 0 1 1 0 0 1 1 Cin 0 1 0 1 0 1 0 1 Cout 0 0 0 1 0 1 1 1 C in =input carry C out=output carry ОЈ =sum A and B=input variables ОЈ 0 1 1 0 1 0 0 1 A B ОЈ=(A B) Cin Cin (A B) C in Cout=AB+(A B)Cin AB Complete Logic circuit for a full- adder 2 2. Use 74HC85 comparators to compare the magnitudes of two 8-bits numbers. Show the comparators with proper interconnections.(10 marks) Answer 74HC85 comparator is 4 bit comparator, so we need two 74HC85 comparator to compare the magnitude of two 8 bits numbers. They are connected as the following figure. LSBs A0 A1 A2 A3 +5V 0 A 3 A>B A=B A<B 0 B0 B1 B2 B3 3 A>B A=B A<B B 74HC85 MSBs A4 A5 A5 A6 B4 B5 B5 B6 0 A 3 A>B A=B A<B 0 3 A>B A=B A<B Output B 74HC85 Q.3 What is multiplexers and draw a logic diagram for 4-inputs multiplexers.(20 marks) Answer A multiplexer (MUX) is a device that allows digital information from several sources to be routed onto s dingle line for transmission over that line to a common destination. The basic multiplexer has several data input lines and a single output line. It also has data select inputs which permit digital data on any one of the inputs to be switched to the output line. Multiplexers are also known as data selectors. S0 S1 0 o o 1 D0 D1 Y D2 3 D3 Data Select Inputs S1 S0 0 0 0 1 1 0 1 1 Input Selected D0 D1 D2 D3 Logic diagram for a 4-input multiplexer 4. (a) Convert the binary number 0101 to Gray code with exclusive- OR gates.(10 marks) (b) Convert the Gray code 1011 to binary with exclusive- OR gates.(10 marks) Answer (a) Binary = 0101 Binary Gray LSB 1 1 0 1 1 0 1 0 MSB Gray code for binary 01012 is 0111 4 (b) Gray Code = 1011 Gray Binary LSB 1 1 1 0 0 1 1 1 MSB Binary number for Gray code 1011 is 1101 5. Implement the logic function specified in table by using a 74LS151 8-input data selector/multiplexer. Compare this method with discrete logic gate implementation. (10 marks) 5 Inputs Output A2 A1 A0 Y 0 0 0 0 0 0 1 1 0 1 0 0 0 1 1 1 1 0 0 0 1 0 1 1 1 1 0 1 1 1 1 0 Solution: Y= 2 1A0+ 2A1A0+A2A1 0 EN Input Variables +5V A0 A1 A2 0 2 001 011 101 110 MUX G Y= 0 1 2 3 4 5 6 7 74LS151 2 1A0+ 2A1A0+A2A1 0 6 The implementation of this function with logic gates would required four 3-input AND gates, one4-input OR and three inverters unless the expression can be simplified. 6. (a) Draw the logic diagram for a 1-line-to-4-line demultiplexer.(10 marks) (b) The serial data input waveform (Data in) and data-select inputs (S0 and S1) are shown in figure. Determine the data-output waveform on D0 trough D3 for the demultiplexer.(10 marks) Data in S0 S1 Answer (a) A 1-line-to-4-line demultiplexer Data Input Select lines S0 o S1 o D0 D1 D2 Data Output lines D3 (b) 7 Data in S0 S1 D0 D1 D2 D3 7. (a) Determine the Q output waveform if the inputs shown in figure are applied to a gated S-R latch that is initially RESET. (b)Determine the Q output waveform if the inputs shown in figure are applied to a gated D latch, which is initially RESET. (20 marks) 8 S R EN Solution: 9 8. Determine the Q and Q output waveform of the flip-flop in figure for the S, R and CLK input in figure. Assume that the positive edge-triggered flip-flop is initially RESET. (10 marks) CLK 1 2 3 4 5 6 CLK S R Q S C R Q o Solution: 1. At clock pulse 1, S is LOW and R is LOW, so Q does not change. 2. At clock pulse 2, S is LOW and R is HIGH, so Q remains LOW (RESET). 3. At clock pulse 3, S is HIGH and R is LOW, so Q goes HIGH (SET). 4. At clock pulse 4, S is LOW and R is HIGH, so Q goes LOW (RESET). 5. At clock pulse 5, S is HIGH and R is LOW, so Q goes HIGH(SET). 6. At clock pulse 6, S is HIGH and R is LOW, so Q stays HIGH. 9. The waveform in figure are applied to the J, K and clock inputs are indicated. Determine the Q output, assuming that the flip-flop is initially RESET. (10 marks) 10 Solution: 10. For the positive edge-triggered J-K flip-flop with preset and clear input in figure, determine the Q output for the inputs shown in the timing diagram in part (a) if Q is initially LOW.(10 marks) 11 1 2 3 4 5 6 7 8 9 CLK PRE CLR HIGH PRE o Q J C o R Q o CLR Solution: 12 11. (a) A certain application requires a one-shot with a pulse width of approximately 100ms. Using 74121 show the connections and the component values. (b) Determine the values of REXT and CEXT that will produce a pulse width of 1 Вµs when connected to a 74LS122. (20 marks) Solution: 13 (a) (b) 12.(a) What is the output width for a 555 mono stable circuit with R1=2.2 kв„¦ and C1=0.01ВµF? (b) A 555 timer configured to run in the as table mode (oscillator) is shown in figure. Determine the frequency of the output and duty cycle. (10 marks) Solution: (a) tw = 1.1R1C1 = 1.1(2.2k-ohm)(0.01 micro-F) = 24.2 micro-s. 14 +5.5V R1 2.2kв„¦ VCC 4.7 kв„¦ R2 THRESH TRIG C1 0.022 ВµF C2 0.01ВµF (b) 13. A 4-bit asynchronous binary counter is shown in figure. Each flip-flop is negative edgetriggered and has a propagation delay for 10ns. Develop a timing diagram showing the Q output of each flip-flop and determine the total propagation delay time from the triggering edge of a clock pulse until a corresponding change can occur in the which the counter can be operated. (10 marks) 15 HIGH вЂў вЂў вЂў FF0 вЂў CLK FF1 Q0 J0 вЂў FF2 Q1 J1 o C вЂў 2 3 4 5 6 вЂў o C K2 7 8 9 10 11 Q3 J3 o C K1 1 FF3 Q2 J2 o C K0 CLK вЂў K3 12 13 14 15 16 Q0 Q1 - Q2 Q3 Solution tp(tot) = 4 x 10ns = 40ns The maximum clock frequency is Fmax = (1/ tp(tot)) = 1/40ns = 25 MHz 14. Show how an asynchronous counter can be implemented having modulus of twelve with a straight binary sequence from 0000 though 1011. (20 marks) Answer When the counter gets to its last state, 1011, it must recycle back to 0000 rather than going to its normal next state of 1100 as illustrated in the following sequence chart. Q3 Q2 Q1 Q0 0 . . . 1 0 . . . 0 0 . . . 1 0 . . . 1 Recycles Normal next state 16 1 1 0 0 12 decoder o HIGH FF1 FF0 Q0 J0 o C CLK K0 CLR o CLK 1 2 3 FF2 Q1 J1 Q2 J2 o C o C K1 K2 K3 5 o 6 7 Q3 J3 o C o 4 FF3 o 8 9 10 11 12 Q0 Q1 Glitch Q2 Q3 Decoder Output Glitch 17 15. Design a counter with the irregular binary count sequence in the state diagram of figure. Use J-K flip-flops.(30 marks) 001 (1) 010 (2) 111 (7) 101 (5) Solution; PRESENT STATE Q2 Q1 Q0 0 0 1 0 1 0 1 0 1 1 1 1 OUTPUT QN 0 0 1 1 TRANSITION Q N+1 0 1 0 1 NEXT STATE Q2 Q1 Q0 0 1 0 1 0 1 1 1 1 0 0 1 FLIP-FLOP J 0 1 X X INPUTS K X X 1 1 18 Q1 Q2Q1 0 1 00 x 0 01 1 x 11 x x 10 x x Q2Q1 0 0 1 00 x x 00 x 1 01 1 x 01 x x 11 x x 11 x x 10 x x 10 x 1 Q1 Q2Q1 J0 map 0 1 x x 00 x x 01 x x 01 1 x 11 x 1 11 x 1 10 x 0 10 x 1 Q1 Q2Q1 0 1 00 x 1 01 x x 11 x 0 10 x 0 K0 map K1map K2 map J0 1 J1 map 1 J0=1,K0= 2 J1 =K1 =1 J2 =K2 =Q1 HIGH 0 Q1 Q2Q1 J2 map Q1 Q1 Q2Q1 Q0 HIGH Q2 Q1 J1 C C K0 K1 J2 C K2 o 2 19 16. Develop a synchronous 3-bit UP/DOWN counter with a Gray code sequence. The counter control input is 1 and count down when the control input is should count up when an UP/ 0. (30 marks) Solution: 000 110 PRESENT STATE 001 Q2 0 0 0 0 1 1 1 1 Q1 0 0 1 1 1 1 0 0 Q0 0 1 1 0 0 1 1 0 OUTPUT TRANSITIONS QN+1 QN 0 0 0 1 1 0 1 1 J 0 1 X X 100 011 101 010 111 Q0Y 00 Q2Q1 00 01 11 10 Q0Y Q2Q1 01 10 Q2Q1 Q0Y 00 Q0Y 00 01 2 1 01 11 10 00 01 11 10 00 01 11 10 Q1 11 11 10 Q2Q1 K X X 1 0 00 0 01 0 11 1 100 00 X 01 X 11 0 10 X X 0 X X 0 X X 1 1Y 2 Q0Y 00 Q2Q1 00 01 11 10 2Q1 01 11 Q0Y Q2Q1 00 01 11 2Q 1Y 10 00 01 11 10 Q2Q1 Q2Q0Y K1 map 10 Q2 1Y Q2Q1Y 2Q0 0Y K2 map NEXT STATE Y=0(Down) Y=1(Up) Q2 Q1 Q0 Q2 Q1 Q0 1 0 0 0 0 1 0 0 0 0 1 1 0 0 1 0 1 0 0 1 1 1 1 0 0 1 0 1 1 1 1 1 0 1 0 1 1 1 1 1 0 0 1 0 1 0 0 0 Q2 20 1Y K0 map 1 0 X X 0 1 X X 0 0 X X 0 0 X X 0 1 0 1 X X 1 0 X X 0 1 X X 0 0 X X 0 0 X 0 0 X X 0 0 X X 0 1 X X 1 0 X 1 0 1 0 X X X X X X X X X X X X X X X X 0 1 0 1 1 0 1 0 21 2 Q2 1 Q1 0 Q0 Y J0 Q0 C K0 J1 0 Q1 C K1 J2 1 Q2 C K 2 22 CLK 17. Design a binary counter with the sequence shown in the state diagram of figure. (20 marks) 0 3 11 9 5 7 Solution: 0 J3 Q3 Q3 Q2 J2 Q2 Q1 J2 1 1 Q1 J0 Q0 1 K3 o 3 3 Q1 K2 o 2 K2 o 1 3 Q2 o K0 Y CLK 23 0 18. Use 74LS160 counters to obtain a 10KHz waveform from a 1MHz clock. Show the logic diagram. (10 marks) Solution: To obtain 10 KHz from a 1MHz clock requires a division factor of 100. Two 74LS160 counters must be cascaded as shown in figure. The left counter produces an RCO pulses for every 10 clock pulses. The right counter produces an RCO pulse for every 100 clock pulses. D0 D1 D2 D3 D0 D1 D2 D3 3 4 CTR DIV 6 5 3 4 5 6 CTR DIV 10 6 10 1 9 ENP RC0 ENT >C 14 CLK 1MHz 13 12 11 15 7 ENP 10 ENT 2 >C RC0 14 13 12 15 10KHz 11 Q0 Q1 Q2 Q3 Figure:A device by 100 counter using two 74LS160 decode counters. 19. Implement the decoding of binary state 2 and binary state 7 of a 3-bit synchronous counter. Show the entire counter timing diagram and the output waveforms of the decoding gates. Binary 2 = 2Q1 0 and binary 7 = Q2Q1Q0 .(20 marks) 24 Solution; FF2 HIGH FFO FF1 Q0 J0 FF2 J1 J2 >C >C >C >C >C >C K1 K2 0 K0 MSB 1 7 2 CLK 1 2 3 4 5 6 7 8 Q0 Q1 Q2 2 Figure: A 3bit counter with active-HIGH decoding of count 2 and count 7. 25 20. Determine the overall modulus of the two cascaded counter configurations in figure. (10 marks) Input Input CTR DIV 8 CTR DIV 12 CTR DIV 10 CTR DIV 4 CTR DIV 16 CTR DIV 7 Output CTR DIV 5 Output Solution; In figure (a), the overall for the 3 counter configuration is 8 12 16 =1536 In figure (b), the overall modulus for the 4 counter configuration is 10 4 7 5 =1400 26

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