WSM Mechanics

Main parts

  • An open model train car of type Nd (you may use basically any other car that fits you needs).
  • Single-cell LiPol battery (500 mAh, 3.7 V).
  • Axis with perforated wheel.
  • GP1S23 opto sensor.
  • Main PCB connected to sensor & battery.
  • Bluetooth module HC-05 connected to main PCB.


  • Use fixed coupling, the measured data will be much clearer.