I need to know how to slow down my 2v brush motor to <40 RPM and >20 RPM. I'm using a 9v battery, and im wondering what length of wire, and /or resistors i would need to achieve this. The wire is from a master/slave cord for an old computer, its copper and as thin as hair, do not know its size, or resistance it has. Basically i need to know; How many volts to make a 2v really slow, and how to achieve that voltage with wire length and/or resistor combinations from a 9v.