10
The electrode system immersed in an analyzable solution generates U
linearly dependent on pH value.
Signals (U) from the electrode system and temperature sensor are applied to
the convertor unit where they are amplified and digitized.
The measured U of the pH-meter electrode system is translated into pH
value in view of analyzable solution temperature, i.e. temperature compensation
occurs automatically. The compensation relates to only U variations of the
electrode system.
1.5.3 pH-meter design
MAPK-903 pH-meter is shown in Figure 1.1a and MAPK-903/1 pH-meter is
illustrated in Figure 1.1b.
The convertor unit 1 enclosed in a plastic tight casing, transforms signals
from the electrode system, displays measurement results and transmits data to a
PC.
The convertor unit front panel carries:
a display screen 2 to show measured pH, pH
25
, U, and temperature;
indicate battery charge, date, time, and navigate in the display menu; and
keys 3.
The convertor unit rear panel bears a cover of the dry cell compartment.
The upper end face of the MAPK-903 pH-meter convertor unit carries:
a tight cable entry 4 from temperature sensor 7;
jack 5 for connection of the combined electrode 8; and
jack 6 for connection to PC.
Unlike MAPK-903 pH-meter, the jack 5 of MAPK-903/1 pH-meter convertor
unit is used for connection of an adapter 9 of which jack accepts the measuring
electrode 10. The socket on the adapter bracket accepts the reference electrode
plug 11.
The upper end face of the MAPK-903 pH-meter convertor unit carries:
a tight cable entry 4 from temperature sensor 7;
jack 5 for connection of the combined electrode 8; and
jack 6 for connection to PC.
Unlike MAPK-903 pH-meter, the jack 5 of MAPK-903/1 pH-meter convertor
unit is used for connection of an adapter 9 of which jack accepts the measuring
electrode 10. The socket on the adapter bracket accepts the reference electrode
plug 11.