Rectifier Circuits

Simply defined, rectification is the conversion of alternating current (ac) to direct current (dc). Rectifiers are found in all dc power supplies that operate from an ac voltage source. Because of their ability to conduct current (electrons) in one direction and block current in the other direction, diodes are used in circuits called rectifiers that convert ac voltage into dc voltage. A power supply is an essential part of each electronic system from the simplest to the most complex.


Diodes are the main components of rectifier circuits, because they let current flow in only one direction. The anode terminal is the base of the triangle, while the cathode terminal is the tip of the triangle and marked with a silver ring or with a line in its schematic symbol

In the following experiments, you will become familiar with the following types of rectifier:

  • Half-wave rectifier
  • Full-wave or bridge rectifier

Furthermore, you will become familiar with filters used at the output of rectifier circuits. The usual elements of such circuits are:

  • Capacitors
  • Inductors


Rectifiers with transformer-coupled input

Although you are not able to see it directly in this course, the UniTrain-I power supply (black box with cable connected to the line) has one transformer inside! A transformer is often used to couple the ac input voltages from the source to the rectifier circuit. Transformer coupling provides two main advantages:

  • It allows the source voltage to be stepped up or stepped down as needed according to the  relationship


    (where V2 is the output voltage, V1 is the input voltage, N2 is the number of turns of the output or secondary side and N1 is the number of turns of the input or primary side)
  • The power source is electrically isolated from the rectifier circuit, thus reducing the hazard through electric shock.


Transformers allow low input voltages to be stepped up to higher levels or high input voltages to be stepped down to a safer voltage level


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