Instrumentation amplifier full scale

Narrow and broad MW standards were injected onto the HPSEC-DV system at concentrations near 1 mg/mL and 2 mg/mL, respectively. Initially, in order to obtain a usable differential pressure chromatogram, the lignin samples were injected at concentrations near 20 mg/mL, with an instrument (A-D amplifier) gain setting of 1 (0-1.0 volt Full Scale). As the... 

The most desirable recorder is one which has a 1-mv span, a full-scale deflection time of about 1 sec, and a chart speed of 15 in. per hour. These recorders are, however, quite expensive. A small 10-mv recorder is available, and this is quite satisfactory for most purposes. It may be converted to a fairly satisfactory 1-mv recorder with the scale-change kit which is available. Another recorder is available at one-fifth the price of the latter instrument, but since this is basically a 0-to-l milliammeter, it requires an amplifier between the bridge and itself. 

The use of the flapper-nozzle amplifier increased the sensitivity of the controller but at the expense of its proportional action. The flapper-nozzle was so sensitive that the controller had a proportional range of about 1 per cent of full-scale movement and hence became the equivalent of an on-off controller. Developments during the 1920s concentrated on trying to modify the flapper-nozzle valve action so as to increase its proportional range, and by 1930 several instrument companies offered controllers with a proportional band of 5 to 7 per cent of fiill range. 

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