Electronics Paper 2, Nov/Dec. 2014  
Questions: 1 2 3 4 5 6 7 Main
General Comments

Question 1
  1. Draw and label the block diagram of an oscillator.
  2. State two conditions for oscillation to occur.
  3. State two advantages of negative feedback in an amplifier.

          The expected answers were:

(b)        Conditions for oscillation to occur
            (i)         The gain must be greater than 1.
              (ii)      The feedback signal must be in phase with the input signal
            (i)         | Aβ | > 1
            (ii)         =  
(c)        Advantages of negative feedback
            (i)         Circuit stability
            (ii)        Reduction in distortion
            (iii)       Increase in bandwidth
            (iv)       Reduction in noise
            (v)        Gain stability
            (vi)       Causes changes in the values of input/output impedance


The question was on Oscillators and Amplifiers. It was quite unpopular with the candidates. Candidates’ average performance was reported to be poor.

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