Guys let me explain my situation first...im a second semester student who is pursuing a diploma...so...i dont know much...hope u guys can help me out...thanks alot in advance This is my problemesign a DC regulated power supply(AC to DC)that is able to display the digit 0 to 7 in an LED array for indication purpose. These are the specs: 1. 3 control switches for digit display 2. input 240V r.m.s from TNB(its the power station name in my area) 3. The current in each LED is 10 ~ 20mA 4. Only discrete components allowed(means no IC...) 5. power indicator and necessary safety feature required. well i manage to figure out the starting part....this is how it goes 1)step down transformer 2)full wave rectifier(bridge) 3)filter(capacitor) 4)zener diode(as regulator) So...any help?