RECTIFIER CIRCUIT FOR LED APPLICATIONS

LED DRIVER CIRCUIT

Light Emitting Diode is a special kind of diode that emits energy in the visible band of the electromagnetic spectrum. However, it conducts in forward bias the same as the p-n junction diode. It is used as an optoelectronic device. 

Now let me ask you a simple question. At our home we get 230 volts AC supply, can we give this directly to an LED? The answer should be Of course not. This is because an LED needs a constant current input. Thus to serve this purpose, we need a driver circuit. 

what is OPTOELECTRONICS ?

It is a branch of Technology which deals with the combined use of Electronics and Light

DESIGN OF LED DRIVER CIRCUIT

• To the main supply, an AC capacitor is connected in a line with the mains supply.
• Then, a resistor of 390k ohm is connected in parallel with this capacitor. This is to discharge the capacitor in the absence of supply. One more resistor of 10Ω is connected between the mains supply and the rectifier which can be called fuse here.
• To make the incoming AC voltage as DC, we use the Full-wave Bridge rectifier. Its capability is 1.5A for current.
• Now, bridge rectifier output is filtered using a capacitor (C filter) of 4.7μF.
• Zener diode is used next for regulating the output of the full-wave bridge rectifier. Keeping in mind the current that goes to Zener, we have connected a resistor of 22 KΩ in series. The value of the Zener voltage is 4.7 volts.
• Once more the Zener output is filtered with a capacitor of 47 μF, and finally given to the LED (load).

ADVANTAGES

• Simple
• Small in Size
• Affordable
• Efficient

LIMITATIONS

• Only for single phase
• Only for Domestic use

APPLICATIONS

• Decoration and Lighting
• Automobiles
• Door Bells