The impulse sensor consists of a plastic housing. Inside of it three electrically not interconnected chains are placed on a board. Each of them consists of a resistor and reed connected in series. The impulse sensor consists of a driving element or quantized scale, divided into a corresponding number of sections and sensitive elements.

The impulse sensor is mounted on the cover so, that when the gears rotates the gearbox, reed contacts S1 and S2 close when a permanent magnet passes by. The resistance change on the impulse measurer contacts is applied to an electronic corrector connected to it in order to create a sound, with a frequency proportional to the consumption. The S3 reed contacts remain open.

The impulse sensors percept the changes in the parameters of the air, humidity or temperature, react to these changes and give a corresponding impulse to the command devices. The impulse sensor can be built on base of various physical phenomena: electrical, mechanical, magnetic, and optical.