Autumn 2006 Exam: Higher Certificate in Electronic Engineering - Analogue Electronics, Exams of Digital & Analog Electronics

Download Autumn 2006 Exam: Higher Certificate in Electronic Engineering - Analogue Electronics and more Exams Digital & Analog Electronics in PDF only on Docsity! Cork Institute of Technology Higher Certificate in Engineering in Electronic Engineering – Award (NFQ - Level 6) Autumn 2006 Analogue Electronics (Time: 3 Hours) Instructions Answer Question 1 [28 marks] and any four other questions [Each 18 marks]. Maximum available marks is 100. Examiner: Mr. T.Connolly Mr. J. Berry Dr. R. O Dubhghaill Q1. (a) Draw circuit diagrams for each of the following. (i) op-amp differentiator. (ii) 3 input-summing amplifier. (iii) Common emitter amplifier (iv) Non-inverting op-amp amplifier. (v) Op-amp. peak detector [10marks] (b) Draw the circuit diagram of an AM demodulator. Explain in detail the operation of the circuit. [10marks] (c) Draw a circuit diagram of a series transistor voltage regulator. Compare and contrast this with the simple zener diode regulator. [8marks] Q2 (a) Compare A.M. and F.M. in terms of the following:. (i) Bandwidth (ii) Ease of demodulation (iii) S/N ratio [3marks] (b) Draw suitable waveforms to illustrate A.M. and show how the depth of modulation m can be obtained using the waveforms [5marks] (c) Draw the block diagram of an A.M. superheterodyne receiver and briefly explain the function of each block. [8marks] (d) For A.M. explain the term Image Frequency (I.F.). If the I.F.frequency is 470 kHz and the wanted carrier frequency is 1000KHz, calculate the image frequency. [2marks] Q3. (a) Draw the small signal equivalent circuit of a bi-polar transistor. Explain each component in the circuit. [4marks] (b) Draw the circuit diagram of an emitter follower. [3marks] (c) Draw the small signal equivalent circuit of the amplifier in part (b) [3marks] (d) Using the circuit in part (c), derive the equations for input resistance and voltage gain of the circuit in part (b) [8marks] 2 Q4. (a) Explain why a transmission line must be terminated in its characteristic impedance... [4marks] (b) State typical values for the characteristic impedance of (i) coaxial cable (ii) twin feeder cable [2marks] (c) Explain (i) Voltage reflection coefficient (ii) Voltage standing wave ratio (iii) Attenuation coefficient (iv) Phase change coefficient [4marks] (d) A transmission line has a characteristic impedance of 120 ohms and is terminated in a load of 200Ω. Calculate (i) Voltage reflection coefficient (ii) The Voltage standing wave ratio (iii) The maximum and minimum voltages on the line if the incident voltage is 300V. [8marks] Q5 (a) Explain the differences between class A, class B and class C power amplifiers [3marks] (b) Draw the circuit diagram of a class A transformer loaded audio power amplifier and explain its operation. [10marks] (c) A class A transformer loaded amplifier is operated from a single supply of 30V with a dc collector current of 10mA. If the AMP is driven to 60% of its maximum value Calculate (i) A – C o/p power (ii) Efficiency of the amplifier. [7marks] Q6. (a) For the Irish analogue TV system State (i) Field Frequency (ii) Line Frequency (iii) Frame Frequency (iv) Intercarrier Sound Frequency (v) Sound I.F Frequency (vi) Vision I.F Frequency (vii) Colour Subcarrier Frequency (viii) The Channel Bandwidth [8marks] (b) Explain the term Aspect ratio when applied to a TV picture. [2marks] (c) For a 625 line black and white TV signal calculate the bandwidth required if the aspect ratio is 4 : 3. [3marks] Q7. (a) Draw the circuit diagram of a 741 op amp astable multivibrator. [6marks]