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Operational Theory
Note that instrument air at a pressure of 70 to 80 psig is needed to
activate the proper valves.
2.4
Electronics and Signal Processing
T he Model BDS 3960 Oxygen Analyzer uses an 8051
m icrocontr ol l er wi th 32 kB of RAM and 8 kB of ROM to cont rol signal
processi ng,, i nput / output, and di splay functi ons f or the analyzer . Most of
t he processi ng power and deci si on making is done by t he soft war e
r unni ng on t he pocket PC (P PC). Syst em power is suppli ed fr om a
uni versal power supply module desi gned to be compat ibl e wi t h any
i nt er nat ional power sour ce.
The signal processing electronics including the microprocessor,
analog to digital, and digital to analog converters are located on the I/O
board at the bottom of the case. The preamplifier board is mounted on
top of the I/O board. These boards are accessible by sliding the front out.
Figure 2-7 shows a block diagram of the analyzer electronics.
In the presence of oxygen the sensor generates a current. A current
to voltage amplifier converts this current to a voltage which is further
amplified in the second stage amplifier.
The output from the second stage amplifier is sent to an 12 bit
analog to digital converter that is located in the same chip as the
microprocessor. The amplifier board also reads the ambient temperature
Teledyne Analytical Instruments
Figure 2-6: Flow Diagram
BDS 3960
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