CCE 301L Midterm, Spring 2012

CCE301L: Electronics Laboratory Midterm Exam Dr. Adel Chit (Beirut) AMERICAN UNIVERSITY OF SCIENCE & TECHNOLOGY DEPARTMENT OF COMPUTER AND COMMUNICATIONS ENGINEERING CCE 301L: Electronics Laboratory Spring 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 of for scratch or for your answers. Do not detach any sheet from the question booklet. This exam consists of 2 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 : 15 3 : 10 4 : 20 5 : 10 6 : 10 7 : 10 8 : 05 9 : 10 SCORE /100 1 CCE301L: Electronics Laboratory Midterm Exam Dr. Adel Chit (Beirut) Question #1 (10 points) Draw a circuit to measure the forward characteristic of a semiconductor diode. Indicate also how to measure the current and the voltage. Question #2 (15 points) a. State the difference between an ideal and a real transformer. (5 points) b. Draw the equivalent circuit of a real transformer. How can you measure the impedance of a transformer. (10 points) Question #3 (10 points) a. Draw the circuit of an ac-dimmer with a resistive load (incandescent lamp). (5 points) b. Suppose this load has to be supplied by a dc-voltage. How your new circuit will look like? The dimmer remains the same but you have to change or to add a small circuit to the lamp. ( 5 points) Question #4 (20 points) Given a pure ac-sine wave voltage that supplies a full-wave rectifier bridge. a. How can you measure the PIV of one diode (no calculation). Draw the wave form? (5 points) b. Suppose that one diode is taken away (interruption of the current path) from the bridge. Draw the output voltage and find the PIV for the rest three diodes. (15 points) Question #5 (10 points) a. Design a dual power supply (+18 V…0…-18V) using Zener-diodes and feeding an op-amp with a maximum input current of 25 mA. (5 points) b. State the value ( rate and maximum power) of all components, and the secondary voltage of the transformer.( 5 points) Question #6 (10 points) Design a power supply +6 V for a load with a maximum current of 25 mA without using a transformer. State the value of all components. You have to show all necessary calculation. Question # 7 (10 points) A transistor is switching an inductive-resistive to a dc-power supply. Draw a circuit to protect your device from overvoltage. Question #8 (5 points) Draw the equivalent circuit of an npn- and pnp-transistor and show how to troubleshoot them using a DVM? Question #9 (10 points) a. How can you measure the ripple voltage peak to peak from a filtered and rectified ac-voltage? ( 5 points) b. The average voltage of a filtered dc-output is greater or less than the same rectified voltage without filter. Explain on hand the corresponding waveform. ( 5 points) 2