So the fan runs slowly when the device is on standby and fast when on. What sort of device is it? Does it tell you that it's on standby? What power supply are you wanting to use for the fan?
you mean you have a device and a fan, and you need to run the fan with two volatges?
when the device is standby the fan get only 3V?
and when its on then the fan get 12V?
It's for an Xbox 360. I want to make the fan run on 2 or 3 volt Low speed on standby to cool down the system then make it run on 12volt high speed when it runs.
ok give some detail about teh on/standby signal, whats the voltage level? is it logic hig/low? you can use a simple transistor to drive it with teo different voltages