Full Wave Bridge Rectifier

Before anything, let’s discuss about a bridge rectifier. So, the first question that hits your brain is obviously, “What is bridge rectifier…?” Here the term bridge denotes a circuit, or you can say that a kind of electronic circuit. According to this term, you can understand that bridge rectifier is an electronic circuit made of diodes which were arranged in bridge pattern. The main function of a bridge rectifier is to rectify waves. Being a low cost wave rectification method, full wave bridge rectifier is used in several applications.

Also see Half Wave Rectifier

Wherever steady and smooth Direct Current (DC) voltage is required, full wave rectifier is used. The circuit produces a purely DC output current or voltage.

Full Wave Bridge Rectifier Circuit
Full Wave Bridge Rectifier Circuit

Components of full wave bridge rectifier

Working of full wave bridge rectifier

This bridge circuit works on a simple mechanism.

  • All the four diodes are connected in such a way that they form a bridge network.
  • We use a multiple winding transformer for this circuit.
  • Transformer’s secondary winding is connected to the two points of a bridge which are diametrically opposite to the secondary winding of the transformer.
  • The load resistor is connected at the output.
  • Electrolytic capacitors are connected in parallel with load; as the capacitors act as storage devices.
  • The working of the full wave rectifier is divided into two cycles:
  1. First half cycle
  2. Second half cycle
Full Wave Bridge Rectifier characteristics
Full Wave Bridge Rectifier characteristics

First half cycle

  • The input voltage of the secondary winding is positive on the upper end and negative on the lower end; during the first half cycle.
  • In this, two of the diodes are connected in forward-bias so that the current flows in the forward arm.
  • This current then from the forward arm enters into the load resistor and then flows back through another arm.
  • Other two diodes present in the circuit are connected in reverse-bias, so current cannot flow through those two arms.
  • So, the current begins to flow from the secondary winding of the transformer to the load resistor.
  • And, then returns to the source along the same path via load resistor to transformer.
  • Hence, the first half cycle is completed in the circuit.

Second half cycle

  • Now, it’s completely opposite of the first half cycle of full wave rectifier.
  • The lower end is positive and the upper end of the secondary winding of the transformer is negative in this cycle.
  • So, other two diodes through which the current was not flowing in the first half cycle are now connected in forward-bias.
  • And, current flows through those two arms.
  • And, the flow of current through the load resistor is same as in the first cycle.
  • Then, current traces its path back from the load resistor to voltage supply to complete the circuit.

Peak voltage is obtained and the output voltage is generated.

Applications of the full wave bridge rectifier

  • It is used for detecting the amplitude of the modulating radio signal.
  • They are also used to supply steady and polarized Dc voltage in the welding process.
  • These bridge circuits are widely used in power supply circuit, as they are much cheaper than other transformers.
  • This type of circuit is also used in the capacitor filters.
  • Full wave rectifier is also used for powering up the devices which work on DC voltage like motor and led.

This full wave bridge rectifier circuit is used more than the other rectifier circuits due to its end number of advantages over others.

Also watch Wheatstone Bridge Working Principle and Application

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