As this project concentrates on low-cost solution, I have decided not to use any micro-controllers for this. Because it makes the device cost high. And I have not used any pre-builded sensors which is available in the market. I have solved these two issues by just using some low cost semiconductor devices. PCB soldering was an another issue I was facing, but as time passed, I completed it. After my final setup of my bell at home, the bell rang continuously - I couldn't figure it out why its happening. I again removed all the connection from my main board and checked it in my room and it was working Fine. And I reliased that the SUN is the major source of Infrared Rays. As my device is in direct contact to sunlight, the bell rings. I solved this using a BLACK insuation tape-surrounding it to the photodiode. As black is a good absorber, it does not allow the infrared rays from the sun to pass thorugh it.