Teledyne OT-3 - Manual (Page 19)

Trace Oxygen Analyzer Installation
Teledyne Analytical Instruments 11
2.3.2 Signal Processing
Figure 2-3 is a block diagram of the signal processing electronics
described below.
Figure 2-3: Block Diagram of the Signal Processing Electronics
In the presence of oxygen the cell generates a current. The sensor
has an internal thermistor compensation network.
The output of the sensor is converted to voltage millivolt range.
This output is fed to a voltage amplifier. The internal thermistor network
provides temperature compensation of the sensor output. The resistance
of the network changes with temperature, compensating for the changes
of the Micro-fuel Cell output to temperature.
The output from the temperature compensation amplifier is sent to
an analog to digital converter (ADC), and the resulting digital
concentration signal is sent to the microcontroller.
The digital concentration signal along with input from the front
panel buttons (KEYBOARD) is processed by the microcontroller, and
appropriate output signals are directed to the display and alarm relays.