Bridge Rectifier Circuit

FULL WAVE RECTIFIER (BRIDGE RECTIFIER)

AIM:

To study the characteristics of  Full wave Bridge rectifier with and without filter and calculate its ripple factor.

MATERIALS AND TOOLS REQUIRED:

Solder, flux, knife/blade, soldering iron, desoldering pump and nose pliers.

THEORY:

In a bridge configuration, the number of rectifier elements used is same as that used in full wave rectifier with centre tap.The principal features of bridge rectifier is

1. Current in both the primary and secondary of the supply transformer flows for the entire ac cycle and hence for a given power output, power transformer of a smaller size is used in comparison with that of full wave rectifier.
2. No centre tap is needed in the transformer secondary.
3. Since two diodes are present in series in each conduction path, the peak inverse voltage is shared equally by the two diodes. Peak inverse voltage is V_m

Hence bridge rectifier is used for high voltage applications.

   The output of full wave rectifier is pulsating, it has a dc value of magnitude 2V_m/π and some AC variations called ripples. Certain circuits need very smooth dc voltage. Hence the circuits that converts a pulsating output from a rectifier to a very steady dc level is known as filter, because it filters out or smoothens out pulsations in the output. Here a capacitor of suitable value C₁ connected across the rectifier and in parallel with the load R_L to achieve filtering action. This filter circuit depends on a property of capacitor that it opposes any change in voltage across its terminals. When connected across a pulsating DC voltage, it tends to smoothen out or filter out the voltage pulsations.

Circuit Diagram:

Bridge F W R without filter

Bridge F W R with filter

PROCEDURE

1. The circuit is wired as in the circuit diagram
2. Connect the supply voltage to the primary of the transformer
3. Connect the output terminals to the CRO and observe the input output waveform
4. Measure the dc voltage at the input and output points
5. Measure the dc voltage across the load resistor
6. Calculate the ripple factor, dc output voltage

Observations:

RESULT

Ripple factor ,        r = ………(with filter)

                                = …….. (without filter)