It shows graphic indication or rotation speed and direction:
Green: below nominal speed.
Red: nominal speed is exeeded.

For simplicity and speed, Motor Coil is modelled as a resistor.

Property: (default value)

- Nominal Speed: (60 RPM)
   Speed at nominal voltage.

- Nominal Voltage: (5 V)
   Voltage to reach nominal speed.

- Resistance: (100 Ω)
   Resistance of the winding.
