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Do brushless motors produce electricity? Answered

 I built a bike generator. My science teacher recommended installing a brushless motor instead of my brushed one. 


I just wanted to add something.  A lot of brushless motors harvested from electronics (especially fans) have built-in control circuitry which allows them to be powered from a dc source.  This circuitry modulates the dc power source to create a waveform required to spin the motor.  If you have such a motor you won't be likely to produce any power from it unless you take it apart and bypass the controller circuit.

Well you could use the commutation circuits in the motor to switch an active rectifier, whcih would be more efficient than using a bridge,  but unless you really knew your motor, it would be tricky. A BLDC motor usually has some way of measuring the angle of rotation of the shaft, either in big lumps, or with a shaft encoder.

A brushless motor will give you alternating current (AC) out whereas a brushed motor will give you (lumpy) direct current (DC).   If you're driving filament bulbs from it there won't be any difference between the two but if you're powering something which needs DC with a brushless motor you will need to put in a bridge rectifier and capacitor to get full efficiency from it.