Teledyne 3000PB - Bulkhead mount percent oxygen analyzer - Manual (Page 25)

2-9
Percent Oxygen Analyzer Operational Theory 2
Teledyne Analytical Instruments
dependent resistance that changes the gain of the amplifier in proportion to
the temperature changes in the block. This change is inversely 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.
The digital concentration signal along with input from the control panel
is processed by the microprocessor, and appropriate control signals are
directed to the display, alarms and communications port. The same digital
information is also sent to a 12 bit digital to analog converter that produces
the 0-1 V dc analog percent-of-range signal output and the analog range ID
output. Models with the –M option also have a 4-20 mA dc percent-of-range
signal output and analog range ID output.
Signals from the power supply are also monitored by the microproces-
sor, and the system failure alarm is activated if a malfunction is detected.