2. General Description

Fig. 2 Block diagram

The photocurrent from each detector is amplified in a pre-amplifier before passing to the signal processing circuitry in the control unit.

If transmission is to be monitored, the signal passes directly to the low pass filter. If AU is to be monitored, the reference cell light intensity (IR) is compared with the sample cell intensity (IS) to form log (IR/IS) in a logarithmic circuit before passing to the low-pass filter. The signal finally passes to the range selector before being presented to the output terminal.

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