Basic Electronics Paper 3, May/June 2015

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%