Ernecke's polarized relay presented here is mounted on a frame of non-magnetizable alloy painted black and fixed on a rectangular wooden base (12 x 14 cm) and is protected by a wooden lid.
The polarizing magnet is horseshoe shaped with arms of different lengths and is attached horizontally to the frame. The coil has a resistance of 150 ohms and is wound on a cylinder of soft iron (diameter 3 mm) fixed transversally to the longer arm of the magnet; it has one base in proximity to the longer arm and the other in the space that the other arm would have occupied had it not been shortened.
The mobile armature is fixed laterally to the shorter arm by means of a thin steel plate, with a hole to increase its sensitivity, and is equipped with a spring with an adjusting screw.
The connection of the two terminals of the coil, of the working contact and the rest contact with the corresponding clamping screws is by means of wide strips of nickel-plated brass to be seen on the wooden base. ...continues