for your mobile robots and science projects
This windmill is created from a battery operated fan, purchased from a dollar store. Keep the two AA batteries and connect filter capacitors and a back EMF diode across the terminals. The generator power dynamo will generate a DC voltage proportional to the turning speed of the turbine as determined by the force of the wind. These wind harnessing generators are idea for trickle charging a battery pack when there is insufficient sunlight to power solar cells but strong enough wind to turn the fins.
The finished design includes adding a tail so the propellers will continue to face the wind during changing wind direction. These mini windmills can be added together in series to generate more power. The one shown is a 3-volt unit and includes the batteries and a power switch at the base. The windmill is portable and works well when placed on outdoor mobile robots which are heavy enough to avoid tipping.