The circuit required for changing the output levels is shown in Figure 15.2. The
+ve input to the reference buffer is set by the 2 kΩ potentiometer to 0.7V to offset
the sensor signal level for the minimum level of the process variable. This will give
0V output when the input to the signal buffer is 0.7V. The gain of the amplifier then
can be set to 28.6, giving 10V output with 0.35V input [i.e., 10/(0.7 − 0.35) =
28.6]. Note the use of impedance matching buffers that would be used in instrumentation,
and the signal inversion to accommodate the negative signal. This circuit