### Basic Electronics Paper 3, May/June 2015

 Menu General Comments Weakness/Remedies Candidate's Strength

### Question 1

AIM: To investigate the voltage regulation of the half-wave rectifier circuit.

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

Table 1

 Input voltage (V) a.c Output voltage (Vout) d.c Percentage voltage regulation VAB RL= 1kΩ RL=47Ω RL(removed) RL= 1kΩ RL= 47Ω
1.   Close switch (sw).
2. Measure and record in Table 1 the voltages VAB and Vout.
3.   Open switch (sw) and replace the 1 kΩ resistor (RL) with 47 Ω resistor.
4.   Repeat steps (d) to (e).
5. Open switch (sw) and remove the 47 Ω resistor.
6. Repeat steps (d) and (e) for no resistor in the circuit diagram.
7. Open switch (sw).
8. Using the formulae:

Calculate the percentage voltage regulation of the half-wave rectifier circuit for the

(i) 1 kΩ resistor;

(ii) 47 Ω resistor.

### Observation

The candidates were expected to connect the circuit as shown, measure and record the voltmeter readings and calculate the percentage regulation.
The expected answers were:
Table 1

 Input Voltage (V) a.c. Output Voltage (V) d.c Percentage Voltage Regulation VAB RL = 1K Ω RL = 47 Ω RL (removed) RL =1K Ω RL= 47Ω 9V 11V 8V 12.7V 15.45% 58.8%