8.8 Analogue (electronic) pressure switch 8.8.1 General characteristics The electronic pressure switch is an analogue device whose function is to control the level of water in the tub; it is used in certain models with electronic control systems (EWM2000 - MWM1.5). The electronic circuit is connected directly to the main PCB. 8.8.2 Operating principle 1. Air intake tube 2. Membrane 3. Coil 4. Electronic circuit (oscillator) 5. Core 6. Spring 7. Calibration spring 8. Connector The pressure switch is connected via tube to the pressure chamber. When water is introduced into the tub, this creates a pressure inside the hydraulic circuit that causes the membrane to change position.
This movement of the membrane modifies the position of the core inside the coil, varying its inductance and thus the frequency of the oscillating circuit. The PCB recognizes how much water has been introduced into the tub according to the frequency. SOI/DT 2002-05 eb 71 599 35 23-17