Hi guys. I learned that you need to apply DC biasing to establish your transistor's amplification zone. Some weeks ago I was struggling (as almost we all do with anything related to E.E.) with transistor amplifiers. I had to make 3 amplifiers with 3 different biasing configurations. I read a lot using Malvino's book, and I think I learned how to make the DC model. But when It comes to putting the AC input signal, it becomes almost useless, I had to modify almost all the resistor values, and I still could never get the gain that I had calculated ( I calculated 150X, all I got was 126). I started to play a bit with the resistors until I could get my 150X gain. But my only conclussion was that the biasing is pointless because you'll end up replacing playing with the resistor values to fit your desired output. So, what's the secret?, why would you calculate your DC biasing model if you'll end up with different resistor values to fit your design requirements. I wasted nights asleep but I just couldn't figure out how to get the exact values to fit your desired output.