Teledyne 3000TA-EU - General purpose trace oxygen analyzer - Manual (Page 26)

Operational Theory 3000TA- EU
Teledyne Analytical Instruments
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Figure 2-6: 3000TA Internal Electronic Component Location
In the presence of oxygen the cell generates a current. A current to
voltage amplifier converts this current to a voltage, which is amplified in
the second stage amplifier.
The second stage amplifier also supplies temperature compensation
for the oxygen sensor output. This amplifier circuit incorporates a ther-
mistor, which is physically located in the cell block. The thermistor is a
temperature dependent resistance that changes the gain of the amplifier
in proportion to the temperature changes in the block. This change is in-
versely proportional to the change in the cell output due to the same
temperature changes. The result is a signal that is temperature
independent. The output from the second stage amplifier is sent to an 18
bit analog to digital converter controlled by the microprocessor.