Practical: Rectifier circuit

Introduction

In this practical the input and output of a half wave and full wave rectifier will be investigated with a datalogger.

Method

Depending on the equipment available you can either build the circuit by clipping components together or using a soldering iron. If doing the latter make sure that you get proper instruction on how to use the soldering iron properly. The best way to ensure a good connection is to solder the components onto a printed circuit board like the one in the photo.

Half wave rectification

Construct the following circuit. The red line on the diode is the end corresponding to the line of the symbol.

  • Compare the input and output signals by connecting the "voltage sensor" across the power supply and then the resistor . You can use the scope mode to do this but it is simpler to plot Voltage against time. Make sure the sampling rate is set high enough, it must be a lot higher than the frequency of the AC signal.
Full wave rectification

Disconnect the half wave rectifier and construct the following circuit

  • Use the voltage sensor to compare the input and output signals.

Breadboard method

An alternative way of building this circuit is to use a breadboard, this isn't the board use to cut bread on in the kitchen but a special type of circuit board used to make prototype circuits. The breadboard is made of rows of connected sockets so to connect components together you need to push their wires into the same row. In the piece of board shown the vertical lines of 5 sockets are all connected.

Before connecting the components you first need to convert your circuit diagram to a breadboard circuit, for example the image below shows a combination of resistors drawn for breadboard.

Draw the rectifier circuit for breadboard using a blank like the one shown.

You can test your circuit by building it with Paul Falstads circuit simulator Here is a blank breadboard to build your circuit on.

Blank breadboard

Right click the link and download the file then open it with the circuit simulator applet. For more details about how to use this simulator see Rectifier simulation (Falstad)

If the circuit is made with LEDs you will be able see which way the current flows. LEDs are also diodes (light emitting diodes), the positive side has the longer wire. Try connecting an LED to a battery and see that it only lights if the long leg is connected to the positive terminal.

  • Build the circuit with LEDs then connect a DC power supply each way and see that the middle LED always lights.

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