Question 1

AIM: To determine the common-emitter current-transfer characteristics.

1. Connect the circuit as shown in Figure 1.
2. Ask your supervisor to check the circuit connection.
3. Copy Tables 1 into your answer booklet.

Table 1
     

1.  Close switches S1 and S2.
2.  Set V2 to 12 V.
3.  Set the input voltage (V1) to 1 V, measure and record in Table 1 the current (IC).
4.  Repeat step f for the other values of V1 in Table 1.
5.  Open switches S1 and S2.
6.  Complete Table 1.
7.  Plot a graph of IC (mA) on the vertical axis against IB ( on the horizontal axis.
8.  Determine the slope of the graph in step (j).
9.  Comment briefly on the value of the slope obtained in step (k) with the calculated average value of the d.c. current gain (IB).

The candidates were expected to connect the circuit as shown in Fig.1, measure and record in Tables 1,2 and 3 the different milliammeter and microammeter readings, plot the graph and make some deductions.

The expected answers were:

(c)                                                        Table 1
           

                                        
The candidates, as reported, understood the question and carried out the actions required. As reported, some of the candidates had challenges in taking readings in microamperes range.