CCE 301 Midterm, Spring 2012

CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) AMERICAN UNIVERSITY OF SCIENCE & TECHNOLOGY DEPARTMENT OF COMPUTER AND COMMUNICATIONS ENGINEERING CCE 301: Electronics Spring Term 2011-2012 Midterm Exam April , 2012 Student Name: __________________________ ID Number: _______________ CLOSED BOOK (90 Minutes) IT IS IMPORTANT THAT YOU READ AND UNDERSTAND THE FOLLOWING: Questions are not allowed during the examination. If you believe that there is ambiguity in a specific question, simply write your own assumptions and proceed with the answer. The CHEATING penalty will result in an F in the course. Mobile Phones are strictly prohibited in the examination hall. Programmable Calculators are not allowed in this exam. Borrowing of any material is not permissible. Write your Name and ID Number in the indicated space of the question booklet. You may use the back of any page for scratch or for your answers. Do not detach any sheet from the question booklet. This exam consists of 7 pages. Make sure that you have the correct number of pages. THE WHOLE EXAM SHOULD BE MADE ON THIS QUESTION BOOKLET ANY OTHER SUBMISSION IS NOT GOING TO BE GRADED YOU NEED TO SHOW ALL OF YOUR WORK TO GET COMPLETE CREDIT. Good Luck! PROBLEM POINTS 1 : 10 2 : 10 3 : 15 4 : 20 5 : 20 6 : 10 7 : 15 SCORE: /100 1 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question #1 (10 points) a.Find IB, IE, and Ic in the following fig. αDC= 0.975. (5 points) b. Find VE, VCB, and VCE. (5 points) R1 1k + 3V + V1 10V Question #2 (10 points) a. Find VCE, and VBC. βDC= 55. (5 points) b. Determine whether or not the transistor is saturated. ( 5 points) Q1 NPN Rc 180 Ohm 4 kohn + Vcc 15 V + 5V 2 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question #3 (15 points) a. Determine Ic(sat)for the transistor. (3 points) b. What is the value of IB necessary to produce saturation ? (6 points) c. What minimum value of VB is necessary for saturation ? (6 points) βDC = 150. Assume VCE = 0.1 V +V Vcc 5V + VB R2 1.0 MOhm R1 10k Q1 3 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question # 4 (20 points) Draw the output voltage of the following circuits and indicate the peak value for each wave. Vin= 15Vsinωt for all circuits a. 4 points Vout Vout D1 6V R1 1k + - 15sinwt b. 4 points Vout D1 6V R1 1k + - 15sinwt c. 4 points Vout D2 D1 18 V R1 1k + - 15sinwt d. 4 points Vout Vz10 Vz18 R1 1k + - 15sinwt e. 4 points Vout Vz10 Vz18 R1 1k + - 15sinwt 4 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question #5 (20 points) Given PD= 1 W, Izk= 0.5 mA, and Vz=12 V at Iz = 25 mA, Zz= 10 Ω for a Zener– diode in the following circuit. The resistive load R out is variable and can have any value. Vout Rout Vz12 Rin + - 18 V a. Find the value of Rin that should be used. State the value of Rout in this case. (10 points) b. Find the minimum value of Rout where the Zener-diode is still regulating the voltage. (10 points) 5 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question #6 . a. Light activated b. Light deactivated Q4 NPN Q2 R2 1k D1 DIODE +V V2 12V contact RLY1 12V-coil RLY1 12V-coil contact +V V1 12V D1 DIODE R1 1k Q3 Q1 NPN Q4 NPN Q2 R2 1k D1 DIODE +V V2 12V contact RLY1 12V-coil RLY1 12V-coil contact +V V1 12V D1 DIODE R1 1k Q3 Q1 NPN a. Try to explain in few words the function of this circuit. (5 points) b. State or imagine two applications for this circuit. Explain briefly. (5 points) Remark: Q3 and Q2 is the same photo-transistor. 6 CCE 301 : Electronics Midterm Exam Dr. Adel Chit (Beirut) Question #7 (15 points) Following transistor circuit is given: Bdc=150 +V Vcc R1 1k + VB 5V Rin 100k NPN a. Find the value of Vcc(max) if VCE(max)= 18 V. PD= 600 mW. (10 points) b. What happen to the transistor if VBB= 0 V by taking into consideration item a. (5 points) 7