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?

 

Don't forget the fuse on the AC line, along with insulating the wires when you're doing wiring it up.

We need clarification on your led array. Is it a 5X7 array? Or, a 7-segment LED module? Nonetheless, the logic behind this is going to be intense, especially that you need to use transistors.

Once you come up with the boolean equation, you probably can implement with standard complex cmos methods. Check out implementation in complex CMOS, it is a systematic way to create a logical function via p and n channel devices.

Steve

 

This is apparently the same assignment as this one - http://forum.allaboutcircuits.com/showthread.php?t=14640.

 

yeah
It sounds like the same "Sir" different student.