Okay, so I went to Radio Shack and got the current numbers for the 1.5-3v motor that were talking about:
https://www.radioshack.com/product/index.jsp?productId=2102822&cp=&origkw=motor&kw=motor&parentPage=search
According to the specs on the back, the current at maximum efficiency is .70a (+ or - 15%) and the output .31 watts.
So based on those numbers, what would the Ohm rating be and what resistor should I get? Is a Micro 1-Amp Rectifier Diode a better solution than a resistor? So far, it seems if I add or decrease diodes, I can decrease the volts .8 volts per diode, making it customizable to a degree if I wanted to keep the motor not running at max voltage.
Although, I like the idea of dealing with just 1 transistor. Let's say, I wanted to run the motor at 2.5 volts, so as not to overload the little motor. What ohm rating and wattage rating of resistor should I get based on the current flow indicated in the above specs?
Some of the discussion about burning out the usb ports has me concerned. I thought with a proper resistor in place, the device can't draw more power that what it's given?
So many questions, so much to learn, I had no idea how complicated this could get to get the voltage down to safe levels for this motor. Given, the cost of resistors(10-25cents each) and the $1 fan, this makes it a fun budget project, although it seems like there are several different ways to approach it.
If I was going to take in all the info, from this post, all I want is a way to decrease the 5v usb voltage to 2.5 volts for the motor, in such a way as to make it safe so it won't burn out the fan or usb port.