Can someone give me a circuit diagram of a 9-12V power supply; just a simple one. I'm very new at this kind of stuff. I'd really appreciate it if the parts and the lay-out were included. I hope this is not asking too much. I can't find anything on the internet that's why I posted this.

Thank You!

 

How many ampere do you need from your power supply?

 

have a look at this :
http://www.discovercircuits.com/DJ-Circuits/18VPS1.htm

It may be 18v but you can look at this site to get the Resistor values for different voltages :
http://www.reuk.co.uk/LM317-Voltage-Calculator.htm

Hope this helps

 

If you are new I suggest you to take a linear variable voltage regulator which is quite easy to use.