i have done an experiment
i have took 3 toy motors
one from old tape it is little havy and two small identical from cd players
i have found that when the small motors where coupled together.
5.2 volt was connected to one and the other acted as generator and produced 3 volts.
i saw that the faster it rotated the higher the voltage it produced.
so i tried to cupple small motor so it will turn the the old tape motor.
and it the input voltage was 4 volt and the output was between 5 to 6 volt
i have connected the output to other small motor.
i was excited but it was short. because i have not mesured the current.
the input current was 200mA and the output was 30ma as the motor takes at rest.
is there a way to make it work overunity?
i remember some proposed no load generators.
Try a Peter Lindemann
motor.
http://www.overunity.com/index.php/topic,3716.0.html
Good luck.
Regards, Stefan.