12
Quad pH/mV Amp
Signal Display
The input signal is displayed so that you can see the effect of changing
the settings. The average signal value is displayed at the top left of the
display area. Slowly drifting signals (as from pH electrodes) will be
represented quite accurately, whereas quickly changing signals will be
displayed as a solid dark area showing only the envelope (shape) of
the signal formed by the minimum and maximum recorded signals.
You can stop the signal scrolling by clicking the Pause button at the top
right of the display area
. Click the Scroll button
to resume
scrolling.
You can shift and stretch the vertical Amplitude axis to make the best
use of the available display area (see the Input Amplifier dialog in the
Chart Software Manual
for further details). Changes made here update
settings in the main window of the program.
Setting the Range
Use the Range pop-up menu to select the input range (sensitivity) of the
channel.
At 25 °C, a change of one pH unit corresponds to a 59 mV change.
This relationship is used in
Table 2–1
which shows the pH ranges
corresponding to various pH/mV Amp range settings, assuming that the
pH electrode has a response of zero millivolts at pH 7. For pH
measurements covering a wide range, a setting of 500 mV should be
†
Resolution is 16 bits, or 0.0015%, of range setting.
* In practice this range will be limited by the pH electrode
Range setting (mV)
Resolution
†
(µV)
Range (pH)
Resolution (pH)
±500
15.6
–1.5 to 15.5*
< 0.001
±200
6.25
3.6 to 10.4
< 0.001
±100
3.13
5.3 to 8.7
< 0.001
±50
1.56
6.2 to 7.8
< 0.001
±20
0.625
6.7 to 7.3
< 0.001
Table 2–1
pH ranges
corresponding to pH/mV
Amp settings
Содержание EA168
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