A rectifier is an electronic circuit that can convert the bipolar direction of the voltage into unipolar without changing its amplitude or frequency, which means AC voltage to DC voltage. Anyone can implement the circuit simply using a capacitor-diode combination. The unique property of diodes is they permit the current to flow in a single direction, this circuit utilizes this advantage of diodes. The bridge rectifier is one special type of rectifier which is also called a full wave bridge rectifier circuit. It uses the combination of four diodes that has the advantage of converting both the half cycles of AC input into DC output.
Rectifiers are one of the basic electronic circuits. If you are an electronic hobbyist then this tutorial will help you to get started with your lessons in electronic circuits. A good bridge rectifier power supply (rectifier applications) is essential to start your home electronics lab. Below is the full wave bridge rectifier circuit with working explanation and its schematic in detail.
Full Wave Bridge Rectifier Circuit Diagram
- Step down transformer-1 (230V to 12V or 110V to 12V)
- Diodes-4 (1N4007)
- Capacitor-1 (470µF)
- Led-1 (Red)
- Resistor-1 (1K)
NOTE: You can use a step-down center-tapped transformer as well as an ordinary step-down transformer. If you choose a center-tapped transformer it is possible to control the output DC according to your requirement. By connecting the middle point and a terminal point of the transformer to the rectifier or by connecting both terminal points of the transformer to the rectifier, you can change the voltage.
Working of a Full Wave Bridge Rectifier
- During the positive half cycle of secondary voltage, diodes D1 and D3 are forward biased and diodes D2 and D4 are reverse biased. Now the current flows through D1–>Load–>D3
- During the negative half cycle of the secondary voltage, diodes D2 and D4 are forward biased and rectifier diodes D2 and D3 are reverse biased. Now the current flows through D2–>Load–>D4
- In both the cycles, load current flows in the same direction. Hence we get a pulsating DC voltage as shown in fig (1).
Fig (1). The input-Output wave shape of full wave bridge rectifier using four diodes. Image credit: watelectronics.com
- Addition of a capacitor at the output converts the pulsating DC voltage to fixed DC voltage.
- Upto a time period of t=T/4s, where T is the time period of full cycle, input voltage is increasing, so the capacitor charges up to peak value of the input. After t=T/4s input starts to decrease, then the voltage across the capacitor reverse biases the diodes D1 and D3 and therefore it will not conduct. Now capacitor discharges through the load, then voltage across the capacitor decreases.
- When the peak voltage exceeds the capacitor voltage, diodes D2 or D4 forward biases and as a result capacitor again charges to the peak value. This process continues. Hence we get almost smooth DC voltage as shown in fig (2).
Fig. (2) Filter Output of the full wave bridge rectifier using a capacitor. Image credit: lastminuteengineers.com
Bridge Rectifier Circuit Working Animation
The full wave bridge rectifier is one of the simplest circuits of basic electronics but can be a significant part of any big projects where conversion of ac voltage to dc voltage is necessary, It is cost-effective and required a minimum number of components that anyone can fabricate the circuit within minutes following the above tutorial.