I am using a 12v dc motor with a DPDT switch and a 12v A23 battery. What thickness or type of electrical wire should I use?
If your only desired end result is to get 30mA at no specific voltage, then all you need to look at is how much power is required from a particular motor/generator to get that. I'll ignore inefficiencies, except to assume they are the same, since all we're concerned about is which one requires more mechanical power to get 30mA. BTW, I think you meant required mechanical power, not require mechanical force. Mechanical force would be dependent on things like how fast the motor must turn to generate its rated voltage, any gearing, how large the driving gear/pulley is, etc. Mechanical power is just a measure of how much power you must put into turning the shaft, independent of all those other things. 6V x 30mA 180mW 2V x 30mA 60mW Power required to generate 30mA using a 6V motor/generator is clearly three times higher than using the 2V motor/generator.
