| 摘要 |
1494831 Measuring conductivity of milk D D A FRASER 2 Feb 1975 34129/74 Heading G1N Contaminated fluid, e.g. milk from a mastitis infected animal is detected by passing the fluid from different sources e.g. teats between the electrodes of separate conductivity cells, electrically energizing the cells, comparing the outputs of all cells with each other and detecting any differences. The electrical outputs may also be compared with a reference representing a healthy animal. Conductivity cells 2 mounted in the claw 1 of a milking machine are fed from oscillator 3 with 2À5 KHz A.C. The cell outputs are all compared by circuits AB-CD and, if any difference is found, a warning lamp 12R is illuminated. A "norm" is established for a milk sample from a healthy animal by adjusting potentiometer 4. Comparator 5, which includes a signal lamp then indicates if the conductivity of the milk varies from a norm, even if the outputs of all cells are the same. The comparators AB-CD each comprise a differential amplifier and a bi-stable circuit connected to the comparator output by a variable resistor which alters the trigger level permitting compensation for differences in cell parameter. |
