Ok perfect... now i need to do this..
control the pc fan with the positive cable. Need to turn on and off.
I have tried with TIP137 and transistor or with TIP132 and 6n135 but all my test make the negative conclusion.
Not working both solution...
Please help me. What can I do for controll the fan with positive side ? Only with this system I can read the tachio of the fan... otherwise in the yellow cable there is 10V and damage arduino.
Thank you