i'm working on the motorized pinwheel project form the Arduino projects book and decided to change it a little bit. I've connected a second motor to the first one and it should function as a generator. The first motor is controlled with PWM.
The components i used are the standard ones coming with the arduino starter kit. The MOSFET is the IRF520,1N4007 Diode, 9V battery and both motors are CC motor 6/9V, datasheet http://arduino.cc/documents/datasheets/DCmotor6_9V.pdf
The problem is that i measured a 7.3 V on the generator when setting the PWM to 255 (for the first motor). Since the motor (generator) operating voltage ,according to the datasheet, is 1.5 - 6.5 V this could damage the motor. I would like to read the voltage using the arduino analog input. Would a voltage divider suffice , and how should I proceed if not ? Thank you.