Previously before 10-15 years the majority of electrical lights were either light bulbs (with yellow light) or tube-light sticks (with white light). The major disadvantage of these lighting devices was they consume more electrical energy (in terms of Watt) and gives less luminance (brightness). Light bulb wastes their most of the energy in form of heat. Also the life time of such devices was also short.
Next comes compact fluorescent light (CFL) bulbs. They consume much less electrical energy than light bulbs and tube-light sticks and give more light. But their disadvantage is their intensity cannot be varied. Also their life time is limited to few thousand hours. But because their energy consumption is very less compare to light bulbs, they almost replace them.
Now a days LED light bulbs are becoming more and more popular because they have several advantages over light bulbs and CFL bulbs. Some of their advantages are listed below
· Their energy (electrical) consumption is much more less
· Their luminance is more
· Their intensity can be varied
· Their life time is more
Looking at these advantages one might think LED light bulb must replace all CFL and other light bulbs but it is not so because there are some disadvantages also
· They are much more costlier
· They cannot be directly connected to AC, rectifier – converter is required
· Additional DC driver circuit is required
However they will replace all other light bulbs because their energy consumption is very less. Today all the nations are facing crisis of electrical energy. The electrical energy generated using conventional energy sources like coal, petrol or diesel are becoming scares now. So any how to save such resources saving electrical energy is the ultimate requirement. So the LED light will be used everywhere in near future.
Here I am presenting the tutorial for controlling intensity of LED light using micro controller. For this project Reader should have knowledge of How to Start with AVR.The LED light intensity can be controlled by feeding PWM to it. As the width of applied signal increases the average voltage applied to LED increases that increases its intensity and vice versa. This can be done using any simple PWM generator IC like IC555 or IC741 etc any. But using microcontroller the light intensity can be controlled in precise steps like 10%, 20%, 30%…….. to 100%. Also the light intensity can be varied in accordance to sunlight (day light). Like during day with full sunlight the LED light is off. In the evening as day light decreases LED light intensity increases and in the night LED is fully ON.
So in this simple project 10 V LED light bulb is used. Its intensity is varied using PWM. PWM is generated using AVR micro controller ATMega16. Three push buttons are given to ON/OFF LED bulb and to increase / decrease its intensity. ATMega16 micro controller has built in 4 PWM channels. Out of these four one channel is used to vary intensity of bulb.
Read more: LED Light Bulb Controller using AVR Microcontroller