please, i would be most grateful if i could get the circuit diagram of a multipupose regulated DC power supply
Expecting please

 

What do you plan on doing with your power supply?

If you're going to be working with digital circuits, consider converting a used computer's switching power supply. You can get quite a few amps output for very low cost, but they are really too noisy to use for analog circuits.

Linear power supplies give very stable outputs, but get expensive to build if for more than a few amps, particularly if for a wide voltage range. Your largest single expense will most likely be the transformer(s). Obtaining one that produces more than a couple of amperes at over 30 volts will get pricey. You could always use two transformers with the outputs in series to get higher voltage, or if the same voltage rating, in parallel for greater current. Your supply doesn't necessarily have to have the same current for the negative supply as the positive supply - that is, if you're even thinking about a bipolar supply.

Regulator IC's: there are quite a few out there in various current ratings. Some popular IC's follow.
The datasheets for the following devices can be downloaded from http://www.national.com
LM117/LM317: 1.2v to 37v 1.5A Positive Adjustable Regulator
LM150/LM350: 1.2v to 33V 3A Positive Adjustable Voltage Regulator
LM138/LM338: 1.2v to 32v 5A Positive Adjustable Voltage Regulator
LM137/LM337: -1.2v to -37v 1.5A Negative Adjustable Voltage Regulator
LM133/LM333: -1.2v to -32V 3A Negative Adjustable Voltage Regulator

The datasheets for the following devices can be downloaded from http://www.linear.com/
LT1083/LT1084/LT1085 7A,5A,3A 1v to 30v Positive Adjustable Regulators

The datasheets contain many example circuits and application notes. You decide what you need, and what amount of time and expense you're willing to put into the project.

 

Have you seen "The Projects Collection" section? Lots of PSUs there. What are your specifications?