AA Chapter 4 - Power Supply

Which one of the following devices is used as a regulator in a power supply?

• Capacitor.

• Zener diode.

• Transformer.

• Silicon Diode.

Which one of the following is a disadvantage of a linear voltage regulator over a switching voltage regulator?

• The circuit is more complex.

• It is used in high power application.

• It can be built only as a step-down regulator.

• The response time to changes in load is slower.

Fig 1 shows a basic switching regulator. If the output voltage tends to decrease due to an increase in the load, the conduction time of the switch transistor Q1 is

• longer.

• irregular.

• shorter.

• unchanged.

Refer to Fig 2. Calculate the average voltage (Vdc) of the waveform.

• 4.77 V.

• 9.56 V

• 10.61 V.

• 15 V.

In a simple shunt regulator, a current controlled element is connected in parallel with the load. Identify the current controlled element

• Resistor.

• Capacitor.

• Transistor.

• Zener diode.

Determine the function of a zener diode in a simple shunt voltage regulator.

• Limit the current through the load.

• Establish a constant output voltage.

• Allow maximum current through the load.

• Prevent the output load from being damaged by excessive current.

Which one of the rectifier circuits requires a centre-tapped transformer?

• Bridge rectifier.

• Full-wave rectifier.

• Half-wave rectifier.

• Controlled rectifier.

The capacitor filter in a power supply circuit is used to

• amplify the ac ripple voltage.

• reduce the ac ripple voltage.

• produce the ac ripple voltage.

• maintain the ac ripple voltage.

Determine which component of Fig 3 compensates for fluctuations in the output voltage.

 

• Q1.

• Q2.

• R4.

• Z.

A voltage regulator has an open circuit output voltage of 30 V. When a load is connected across the output terminals, the load voltage drops to 29 V. Calculate the percentage voltage regulation.

• -3.33 %.

• 0 %.

• 3.33 %.

• 3.45 %.