How can make three terminal supply that will have common ground and one will give +12v and other will be -12v.

 

What will you be starting with? For example, will your source be DC or AC? What voltage(s) are available? How much current do you need for your + supply and - supply?

 

What will you be starting with? For example, will your source be DC or AC? What voltage(s) are available? How much current do you need for your + supply and - supply?

i have DC sources +12v i want to use it and current 500mA for both

 

500 mA for a negative supply is quite a bit. The simplest methods of generating a negative voltage produce less than 100 mA, For example, the ICL7660 (switched capacitor) device only produces about 10 mA, which is adequate for many purposes.

If you really need a 500 mA negative supply, you will probably be getting into a switching supply. That is convert to AC then work from that.

 

Hello,

You could do it with a switching circuit:

Bertus

 

i have DC sources +12v

That source must be able to deliver over an amp if you want 500mA for both outputs.