Can I control the flow of a 12V power supply with a 4.5 volt power supply and a IRF3205 mosfet?
This circuit may do what you hope for. Note that the 12V power is &quot;normally on&quot;. That is, if the logic circuit is off, the 12V power will be applied to the load. If you need it to be the other way, it will take more components I think.



simulate this circuit &ndash; Schematic created using CircuitLab