The gate of the transistor is connected to a digital pin of the microcontroller through a voltage divider of two resistors. Therefore, we use a transistor between 5V / 3.3V and ground to control the circuit of the DC motor. On the downside, we cannot control the 5V or 3.3V pin to turn the DC motor on, off or change the speed. The 5V pin as well as the 3.3V pin are the perfect power supply for a DC motor that consumes less than 200mA (because our microcontroller also needs some power). If you want to know in detail if a 5V or 3.3V pin is connected to a voltage regulator or direct to the USB interface, I recommend by Microcontroller Datasheet eBook. What about the 5V pin or 3.3V pin of the microcontroller? Good choice, because these pins are connected to the general power supply of the microcontroller board that used an USB connection with a maximum current of 250mA. Now we know that the digital I/O pins cannot be used as power supply for the DC motor. Therefore, the DC motor convert electrical energy to mechanical energy. If the armature coils are turned on and off in sequence, the rotating magnetic field interacts with the magnetic field of the stator and create a torque, which causes the armature to rotate. The electrical current energizes each armature coil and creates a steady rotating magnetic field. The armature windings are connected to a commutator, basically a rotary electrical switch, that applies electrical current to the windings. The windings of insulated wire on the outside of the armature (armature winding) are wrapped around the armature to concentrate the magnetic field of the stator. The magnets in the stator (poles) and a coil of wires (field winding), with a current running through it, generate an electromagnetic field. The armature is the part of the DC motor that rotates and where external components, like a wheel, are connected.The stator is the stationary part of the motor that provides a rotating magnetic field for the armature.Every DC motor consists of two key components that are important for the functionality:
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