Hi, My problem is very simple, I have a project in which I have to design a voltage regulator out of discrete BJTs, Zeners and resistors etc. the only limitation is that I cannot use an IC. I would prefer not using a zener because i would like to make the output variable through a voltage divider bias if possible. the main problem is that i have looked around a lot, tried to attempt a lot, but i have no idea about any basic design that would allow me to make a low-dropout voltage regulator with mentioned elements. i would be very grateful if someone could nudge me in the right direction, i do not ask for a specific answer, just a general explanation so that i can start working on it and tweak the design as much as i can to my specifications. let's suppose i have a 15 V V(in) and need a 10 V V(out), with as good load and line regulation. can anybody point me to a basic configuration which could allow me to accomplish the task? or any simple configuration that lets the BJT to act as a voltage regulator?