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Electronics Paper 2, May/June 2009  
Questions: 1 2 3 4 5, 6 &7 8 9 10 Main
General Comments

Question 3

(a)        Figure 7 is a transistor a.f. amplifier with a current gain (β) of 100. 
           Calculate the values:
(i)         VCE (max);
(ii)        Ic (sat.).

(b)(i)    Draw the d.c. load line Vce(Q) and Ic(Q)
    (ii)    Show on the d.c. load line in (b) (i) the values for Vce and Ic at Q.


The expected answers were:

(a)(i)    VCE(max) is Vcc = 6v
    (ii)   Ic(max)    =  Vcc/RL = 6/2000  =  3mA. 

(b)       The load line specified by the values of VCE(max) and IC(max)  
            obtained above is displayed below.

(c) Candidates should pick any quiescent point on this load line and specify the coordinates.

This question was on the application of RLC circuits.  This question was quite unpopular.  However, the requirements or the solution was very simple - the load-line is a straight line specified by the points here identified as (O, Vcc) on the

vertical axis and (Vcc, O)on the horizontal axis which was suggested could be made simpler.

The Q-point (the transistor’s operating point) could be selected on this line
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