load when the motor has slowed to a minimum speed the voltage v t across the triac will be at a maximum value v triac off max indicating maximum lift the magnitude of the difference between v triac off max and v triac off min adjusted for line voltage variations will be a function of the load weight the calculated difference is stored by the microprocessor as the initial weight of the load the microprocessor next takes at least two successive measurements of v triac off if the first measurement of v triac off max minus v triac off min is large then the microprocessor can assume the load contains much water and wait for example for 10 minutes before stopping the drum and taking another measurement of load weight if the initial value of v triac off max minus v triac off min is small then the load contains less water and another measurement can be taken for example after 5 minutes successive measurements of v triac off max minus v triac off min are taken to determine data points that will define a graph of the rate of change of the percentage of water retention versus time these can be matched with one of for example 16 different drying curves stored in the memory of the microprocessor from a look up.