Chapter 1

Rectifier Circuits (Power Supply Circuits)

A Power Supply Circuit Consists of:

• A. Transformer

• B. Rectifier

• C. Smoothing Circuit (Filter)

1. Transformer

The transformer provides the required voltage at the secondary winding by stepping the mains voltage up or down according to the circuit requirements.

2. Rectifier

The rectifier converts Alternating Current (AC) into Pulsating Direct Current (DC).

In this experiment, a Bridge Rectifier is used. It consists of four silicon diodes connected in a bridge configuration to produce full-wave rectification.

3. Smoothing Circuit

The simplest smoothing circuit consists of an electrolytic capacitor, which smooths the pulsating DC and produces a more stable DC output.

Experiment 1-1

Bridge Rectifier Circuit

Objective

To obtain a DC voltage suitable for supplying electronic circuits and devices with the required operating voltage.

Theory of Operation

1. The transformer reduces the mains voltage from 220 V AC to a lower AC voltage required by the load.

2. The bridge rectifier converts the low-voltage AC into pulsating DC.

3. The electrolytic capacitor filters the pulsating DC to produce a smoother and more constant DC voltage.

Components Required

• 1 × Power Transformer (220 VAC / 6 VAC, 1 A)

• 1 × Bridge Rectifier (or 4 × Silicon Diodes)

• 1 × Electrolytic Capacitor (Filter Capacitor)

Procedure

1. Test all components using a multimeter.

2. Place the components on the PCB (or breadboard).

3. Solder the components using a soldering iron and solder.

Measurements

1. Measure the DC output voltage using a multimeter.

2. Using an oscilloscope and a load resistor connected across the output terminals, observe the waveform at:

   • The transformer secondary terminals.

   • The bridge rectifier output terminals.

   • The electrolytic capacitor terminals.

3. Record all measured values and observed waveforms.

Bridge Rectifier Circuit

The essential component in a full-wave rectifier is the bridge rectifier. It consists of four diodes connected in a bridge configuration. Bridge rectifiers are available in different shapes and with different current and voltage ratings depending on the application.

Expected Waveforms