Radio,Television And Electronic Paper 2, WASSCE (SC), 2018

Question 4

Question 4
Fig. 3 is a circuit diagram of a power supply unit showing only three stages.

(a) Use Fig. 3 to complete Table 3.

*Stage*	*Name of stage*	*Function of stage*	*One component identified*	*Sketch of output waveform*
1.
2.
3.

In order to ensure a stable output, Fig. 3 requires an additional stage. Draw the circuit symbol of one component need in the additional stage needed to achieve the output.

Observation

The expected answers were:

The expected responses were:
(a) Table 3

*Stage*	*Name of stage*	*Function of stage*	*One component identified*	*Sketch of output waveform*
1.	Transformer	-isolates d.c. voltage from mains -step down voltage	transformer
2.	Rectifier	Converts a.c. to d.c./rectification	Diode
3.	Filter	Smoothens/remove ripples from d.c./filtering	capacitor

(b)      Circuit symbol of additional stage
Zener diode                 I.C. regulator

It was reported that majority of the candidates who attempted Question 4 responded very well.