Tweaking the Motor Control Sketch with Variable Resistor, Arduino for Dummies, Page 135 (MVI 8030)
Tweaking the Motor Control Sketch with Variable Resistor, Arduino for Dummies, Page 135
The motor has a minimum power requirement, below this requirement the motor will only buzz and will not move. The point at which the motor begins to operate can be referred to as the threshold. Switching the motor on only once the threshold has been met prevents the buzzing gives a point when the motor will respond.
This is a dc motor and not a stepper motor. In this example the drawer motor from a CD Rom drive is used. Motors can generate charge if turned and can send current back into the circuit. A diode, which prevents reverse current, is placed in the circuit to prevent the possibility of reverse current being generated, protect the Arduino and possibly the computer which may be connected via the USB.
Arduino digtial output pins are 5 volts at 40 milliamps.
While this provides enough for many sensors this power will not be enough for many relays and motors. (http://arduino.cc/en/Tutorial/Digital... ).