DC Power Supply

Design? Why not just purchase one of many readily available power supplies?

Because it is part of my semester assignment..and i have found the schematic for such a circuit in this link http://www.aaroncake.net/circuits/supply3.asp but i would like to know how can i make the circuit to produce an out put power from 0 - 20v instead of just 0 -15V..do you have any suggestions?

Well if you had actually read the preamble to posting the initial question, you should have seen that we do not do homework. This will be robbing you of your education. I will give you one hint about where you should start. What do you expect the voltage to be after the diode bridge?

By the way, there's a significant error in the schematic you've referenced. Without a properly placed and sized fuse or circuit breaker, this design can eventually ignite and cause an electrical fire.

you mean the value of the voltage??and what significant error would that be?

The answer is in T1.

Seriously now... you couldn't see this?

Anyhow, you should be learning about switch mode supplies not series regulated... that is so last century.

There are advantages and disadvantages for each type (linear and switching) of power supply. Linear supplies are easier for a novice to understand. Linear supplies also produce very little interference signals. A switch mode supply can be made to produce very little interference signal but that requires a real skill of the field.

Step-down Transformer->Full bridge rectifier->Filter-> Fuse(1.5A)->Potentiometer-> Analog display Voltmeter & Ammeter--> Polarity switch

Consult the book for calculation.

Thanks for the help..appreciate it =)

Quote " What do you expect the voltage to be after the diode bridge?"

Answer the question Julian. If you want 20 volts out what do you need to do?

If I had known better, I would have thought this was the same guy here. And, here I thought Finals were over for the season