You probably know that if you spin a motor (mechanically) it generates electricity on what would normally be the inputs. This can be a problem when you shut off a spinning motor and is the reason that protection diodes are built into motor driver circuits. But [Dino] isn’t interested in driving a motor, he wanted to see what he could do with the electricity generated by spinning a stepper motor.
He built the test rig that you see above for this purpose. In the foreground a 12V DC motor is held in place with an electrical conduit clamp. This connects to the stepper motor being tested using a segment of rubber tube. The DC motor provides a reliable input for his experiments, but could be replaced in the future by a propeller to make it wind powered, or by a water wheel. Check out the video after the break to see what kind of juice [Dino] gets out of it, and how it can be used for powering LEDs, recharging batteries, or driving a motor.