26 u2032 is reflected in a different voltage provided to the analog input of microprocessor 57 power for the microprocessor 57 is provided by power supply circuitry 72 for example a rectifier and filter capacitor followed by a solid state voltage regulator which converts line power 74 to microprocessor level dc voltage 71 referenced to a circuit board ground 73 the power supply circuitry 72 may also be contained on the printed circuit board 45 during operation the microprocessor 57 may read the desired water level setting from the rotary switch 48 this setting may indicate one of a set of discrete water levels or more simply may provide for a limited number of automatic settings where the water height is set to an optimum level based on other conditions for example whether or not fabric softener is being used the meaning of the setting of rotary switch 48 is determined by software running in the microprocessor 57 for a typical automatic setting the microprocessor 57 receives water flow information and pressure information from flow sensor 44 and pressure sensor 60 respectively to deduce the size of the load in the wash tub 20 this deduction looks at the rate of change of pressure and hence water head as a function of volume of water and may be.