8/10/2019 Diode Bridge Rectifier Basics

1/1

Diode Bridge Rectifier Basics

A diode bridge rectifier is a device for converting AC, or alternating current electricity into

DC, or direct current. AC electricity goes from positive to negative constantly, whereas DCalways flows in the same direction. AC electricity is more efficient to transmit and easier toconvert into different voltages, so power is transmitted from the station to your house as AC.However, most appliances need DC current to run. A diode bridge rectifier is the most commontype of power supply used to provide this current.

The Transformer

First, a transformer is used to create the desired voltage. When two coils are placed next

to each other and a moving electric current is run through one coil, it induces a moving electriccurrent in the other one. When the second coil has fewer turns of wire than the first coil, it willhave a lower voltage current. his is called a step down transformer. !lectricity comes into thehouse at "#$ volts, but most devices need about ten percent of that voltage. he step downtransformer ad%usts the voltage to the appropriate level.

The Diode Bridge he diode bridge is the heart of the diode bridge rectifier. Diodes wor& li&e electric one'

way valves, only letting a positive or negative charge through, depending on the direction inwhich they are wired. he wire coming from the transformer has two ends. (ecause the currentis AC, when one end of the wire is negative, the other is positive.

!ach end of the wire is attached to two diodes which shunt the electricity into positive andnegative DC wires. )o if end A has a negative charge and end ( has a positive charge, the diodebetween end A and the negative DC wire opens while the diode between end ( and the positivewire opens. When the electricity switches direction, the diode between end A and the positivewire opens and the diode between end ( and the negative wire opens.

Smoothing out the Signal he DC current from the bridge flows in one direction, but it does not do it slowly.

(ecause the AC electricity was constantly pulsing from negative to positive, the DC currentcomes out a little *bumpy* and uneven. o smooth out the signal, most diode bridges use adevice called a capacitor which stores a charge li&e a tiny battery. When the power pulses up,the capacitor absorbs some of it, reducing the surge. When the power drops bac& down on it, thecapacitor releases some of its charge, raising the power. (y flattening the pea&s and raising thevalleys in the current, the capacitor creates a more even and consistent power supply.