Here is the circuit i used. For the 12v power supply i found a spare molex connector from the computer power supply and cut it. I used a multi meter to find which 2 was the positive and negative. (for me the yellow was positive and the black wire beside it was negative). Be careful when doing this and make sure the computer is off to prevent the risk of electric shock. (im not responsible if you get shocked or hurt). If you have any questions just comment below.