Question

Draw the block diagram of regulated power supply, explain function of each block and draw waveforms of each stage.

Answer 1

The block diagram of a Regulated Power supply unit is as shown below

A typical Regulated Power supply unit consists of the following. 

Transformer – Stp Up or Step Down input transformer for the stepping up or down AC power supply. 

Rectifier − A Rectifier circuit to convert the AC signal into pulsating DC components. 

Smoothing − A filtering circuit to smoothen the variations present in the rectified output. 

Regulator − A voltage regulator circuit is used to control the voltage to a desired output level against line and load variations. Load − The load which uses the pure dc output from the regulated output.

Answer 2

Figure shows block diagram of Regulated power supply

Function of each block:

1)Transformer: - converts higher as voltage to lower ac voltage with same frequency.

2)Rectifier: - converts ac signal into dc signal. Rectifiers are of different types.

 i) Half wave rectifier

 ii) full wave rectifier

3) Filter- filter is used to remove unwanted signals. Ac signal is removes and pure dc signal is

passed to regulator block.

4) Regulator: -used to provide constant output.

Answer 3

1. A step down transformer

2. A rectifier

3. A filter

4. A regulator

Operation of Regulated Power Supply:-

Step Down Transformer:-

A step down transformer will step down the voltage from the ac mains to the required voltage level. The turn’s ratio of the transformer is so adjusted such as to obtain the required voltage value. The output of the transformer is given as an input to the rectifier circuit.

Rectifier:-

Rectifier is an electronic circuit consisting of diodes which carries out the rectification process. The input to a rectifier is ac whereas its output is unidirectional pulsating dc.

Usually a full wave rectifier or a bridge rectifier is used to rectify both the half cycles of the ac supply (full wave rectification).

Filter :-

The rectified voltage from the rectifier is a pulsating dc voltage having very high ripple content. Hence a filter is used.

Regulator:

This is the last block in a regulated DC power supply. The output voltage or current will change or fluctuate when there is change in the input from ac mains or due to change in load current at the output of the regulated power supply or due to other factors like temperature changes. This problem can be eliminated by using a regulator. A regulator will maintain the output constant even when changes at the input or any other changes occur.