I have this design homework, where i have to design a biased circuit for a 2N3904 npn bipolar transistor with 5% tolerance resistors.
Here is what the circuit should look like. With a few changes, Vcc is 15V, Rc=0 ohm and the design is to give a nominal collector current of 1.2 mA. Unknown are R1, R2, RE.

http://i115.photobucket.com/albums/n288/johndoe_00/cir1.jpg

I need to design it based on worst case max and min to home in on a good design. Since i have to consider 4 factors ( beta,R1,R2 and Re) and the 5% tolerance. I also dont know what info i need from the datasheet. I need some help or directions, i'm totally lost and confused on this problem.

 

This might be the logic and calculations that you are looking for:

http://www.bcae1.com/transres.htm