An angle measuring device with two pivotable arms connected at a common point is disclosed. The first arm contains a rigidly linked shaft which connects the first arm to a second arm rotatable relative to the first arm. A first electronic sensor, such as a magnetic rotary encoder, determines the angle between the arms. Optionally, a second electronic sensor, such as an accelerometer, determines the angle of orientation of an arm with reference to the plane of the Earth. The microcontroller can be used to aggregate the output of the magnetic rotary encoder with the accelerometers, so as to calculate the angle from the plane of the Earth up to the first arm of the angle measuring device.