I am wanting to build a Dual Polarity Adjustable Power Supply, basically something like this: http://www.jaycar.com.au/productVie...d2=&pageNumber=&priceMin=&priceMax=&SUBCATID= I want to be able to control the two output voltages independently, and ideally be able to limit the current. I would like to be able to use them together to supply say -5v and +5v, with a common ground. Or -5v and +7v to get 5v output and 12v output. So the first thing is to find a schematic to use. I havent been able to find anything that will do exactly what I want, but here are what I've found: http://www.uoguelph.ca/~antoon/circ/vps.htm Single output variable voltage and current. http://home.cogeco.ca/~rpaisley4/PSupply.html LM317 adjustable voltage. http://www.electronics-lab.com/projects/power/003/index.html Single output variable voltage and current. http://www.mitedu.freeserve.co.uk/Circuits/Power/l200var.html Single output variable voltage and current http://www.aaroncake.net/circuits/supply3.htm Dual output variable voltage http://sound.westhost.com/project44.htm Dual output (tracking?) variable voltage Has anyone done anything like this, or knows of a schematic for what I want? Or should I use one of the single output variable voltage/current ones and make it twice, using a centre tapped transformer to supply each set with positive/negative power?