Level sensor and associated control circuit, in particular for a filter for vehicles

Device according to any of claims 1 to 7, further comprising decoupling means (C9, C15, C6, D4) adapted to prevent any direct voltages or currents from flowing across, from or towards said at least one electrode pair (2,3, 4) and said at least one test module (120) and sensing circuit (140).

Device according to any of the preceding claims, wherein said output circuit (180) is adapted to convert and/or adapt and/or combine and/or add the electric state or voltage of multiple circuits or modules connected to respective inputs of said output circuit, in order to provide a single output signal (S7) representative of multiple states of said circuits or modules connected to said inputs.

Device according to any of the preceding claims, wherein said sensing circuit is adapted to switch the value of its own output voltage or signal when the substance establishing contact across the two electrodes has predefined characteristics, such as an electric conductivity greater than a preset value.

Device according to any of the preceding claims, comprising at least one of the following:

• a body adapted to define a chamber for containing a liquid, said electrode pair being arranged within said chamber, and
• a filter arranged at the top of a chamber and adapted to separate a first liquid, in particular fuel, from a second liquid, in particular water, said second liquid having higher specific gravity and/or higher electric conductivity than said first liquid and/or different physical characteristics, and wherein the sensing module of said circuit is preferably adapted to switch the value of its own output voltage or signal when said second liquid establishes contact across the two electrodes.

Method for sensing a substance through an electronic circuit equipped with one electrode pair (2,3), comprising the steps of:

• providing a test signal across said electrode pair (2,3),
• sensing the presence of a substance by means of the signal or voltage value of an output of a sensing module, said signal or voltage value depending on the impedance across said electrode pair, characterized by comprising the steps of:
• controlling an output of said electronic circuit (100) so as to discern signal or voltage values representative of the presence of a substance across said electrode pair (2,3) from signal or voltage values representative of faults of the electronic circuit (100).