Turbidity Sensor - Electrolux WASHING MACHINES Service Manual

10.13 Turbidity sensor

This sensor is installed only on machines equipped with a recirculation pump.
1. Housing
2. Electronic circuit
3. Transparent tube
The sensor consists of a transparent tube installed in the water circulation circuit. A diode (4) on the side of
the tube emits infrared rays (at a frequency of 2.3 KHz, as generated by the electronic circuit) and a
phototransistor (5) on the other side of the tube is hit by the rays. The amount of current conducted by the
phototransistor depends on the how clear the water is: the clearer the water, the more current the
phototransistor conducts and, as a result, the higher the voltage output from the electronic circuit.
Low Conduction
The turbidity sensor operates during the Whites and Colours programmes (COTTON).
It does not operate during the 60°C and 40°C Energy Saving programmes and the Night cycle.
The sensor is calibrated at the end of the wash cycle.
The sensor detects the turbidity of the water at the end of the first rinse and again at the beginning of the
second rinse. The relationship between the two measurements is compared with values programmed on
the board, and the result of the comparison determines whether another rinse is carried
SOI/DT 2005-01 dmm
Medium Conduction
47/67
Maximum Conduction
out.
599 36 82-57