Hello, i am new to circuits design and stuffs. And I need help on infrared break beam circuit. I got no idea how to start it. Basically, i need to have a infrared break beam circuit which will activate a study lamp when a paper is interrupting the infrared beam. So i hope someone will help me. Thanks.

 

Here is a circuit:

http://home.cogeco.ca/~rpaisley4/ATDetIR.html