hi all,

can i know the equation for postitive feedback of a op amp ? and can any of you provide a really detailed of how op amp operates ?
i've a op amp linked through a resistor to a transistor. but i keep getting stuck on how the op amp works. thank you!!

 

Have a look here:

http://www.allaboutcircuits.com/vol_3/chpt_8/index.html

Also, google has many results.