Tuesday, June 18, 2013

Mains Powered LED Lamp

Today I will be writing about a very simple mains powered LED lamp.


Why LED Lamp? 

Look back 10-15 years, people used Incandescent light bulbs of 25-40 Watt range for table lamp which was not a very small amount. As time goes on Fluorescent lamps became more popular and people started replacing those Incandescent lights with Fluorescent ones which resulted in a reduction of energy consumption as now you can use a 7-11 Watt Fluorescent to get the job done.


However now you might get the similar result with just 3-5W LED lamps so here is a very basic one which can be easily assembled and used. 


Diagram:





How It Works:

In this circuit a very simple Capacitive voltage dropper is used. The 0.22uF 400V capacitor will do that job. The 560KΩ Resistor will discharge the capacitor after turning the circuit off to protect against electric shock. Bridge rectification is done by four general purpose diodes or a Bridge rectifier package and it is smoothed by the 56µF capacitor. Smoothing is done to reduce flickering. To reduce inrush current a 560Ω resistor is used in series with the circuit. All these power 15 White LED in series.

Warning: 

This circuit is not mains Isolated so to avoid shock it can not be touched during operation.


Note:


1. Increasing the 0.22µF capacitor will increase the current. However make sure to use a Higher wattage 560Ω resistor if you do so.
2. To protect the LED from higher voltage spike a 50V Zener Diode can be used across the array.


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