Angle Sensor

The angle sensor is made of a magnetic encoder that can detect the position of rotation accurately. Unlike the knob, the angle sensor can rotate continuously, detecting the degrees of rotation and the angular velocity in real time. In addition, the angle sensor can work with a variety of plates to connect to various structural components and thus can be applied in different scenarios.


  • It can work with Makeblock mechanical parts.
  • It can work with Lego pins.

Working principle

In electromagnetism, if we apply a voltage to the two ends of a rectangular conductor, current is generated in one direction. When this happens, if we apply a magnetic field perpendicular to the conductor plane to the conductor as shown in the following figure, the Lorentz force is induced, leading to a path offset of the charges flowing through the conductor.


According to Fleming’s left-hand rule, the direction of the offset can be determined, and the offset direction of the positive charges is opposite to that of the negative charges. Then, as shown in the preceding figure, the positive and negative charges flow through the intermediate conductor along two different paths on the left and right, respectively.

When this happens, an electric potential difference is generated between the sides of the conductor, that is, in a direction perpendicular to that in which the current flows. This is the Hall Effect.

According to the Hall Effect, we know that the current varies with the change of the magnetic field. Therefore, if the change of a magnetic field can be determined based on the change of current and thus the position change of a magnet can be determined, then the position or rotational speed of a shaft equipped with a magnet can be detected.

Real-life examples

  • Some smart servos use magnetic encoders to detect angles.


  • You can set the sound volume of your Apple Watch by turning its Digital Crown.



  • Dimensions: 24 × 36 (mm)
  • Angle precision: ±1°
  • Operating current: 22 mA