Question 2
AIM: To investigate the characteristics of a diode-logic circuit.
- Connect the circuit diagram as shown in Figure 1.
- Ask the Supervisor to check the circuit connection.
- You are provided with Table 1.
- Close switch (s)
- Set switches S1, S2 and S3 to low positions as indicated in Table 2.
- Observe and record in Table 2, the state of the LED as either ON or OFF.
- Repeat steps (e) and (f) for the other states of switches S1, S2 and S3 in Table 2.
- Open switch (s)
- From your result, state the logic gate implemented by the circuit in Figure 2.
- Draw the logic symbol of the gate in (i).
- Write the Boolean expression of the gate in (i).
Observation
The expected responses were:
Both experiments required candidates to connect the logic circuits as shown in Figures 1 and 2, vary the combinations of inputs as instructed and record observations (output) as either ON or OFF. The Chief Examiner reported that majority of the candidates were able to vary the inputs combinations as expected and record the necessary outputs as required. It was however noted that a good number of these candidates could neither interpret nor deduce from their recorded observations the type of logic gate that suits the logic operation established.