Teledyne 238 - Thermal conductivity analyzer - Manual (Page 31)

4-13 TELEDYNE BROWN ENGINEERING
Analytical Instruments
Thermal Conductivity Analyzer Linearizer 4
4.3 Selection of Breakpoint Resistors
It may de desirable to concentrate the breakpoints in some areas of the
voltage range. For example: between 0 and 1in Figure 4-8, the curve is
fairly straight. Between 2 and 3, the curve is modestly straight but with less
slope. Between 1 and 2, however, the it appears substantially curved. Since
the linearizer is to approximate the curve with a series of straight lines, we
would like to have most of the segments on the curved segment; i.e.,
between 1 and 2. This means that most of the breakpoints must be between
1 and 2 rather than evenly spaced out. Similarly for the “S” curve shown in
Figure 4-9, the breakpoints would be concentrated between the points 1–2
and 3–4.
The resistors for the breakpoints are set according to the formula:
R = 299.4/V
bkpt
.
where V
bkpt
is the voltage at the particular breakpoint.
The resistors affected are R6, R8, R10, R12, R14, R16 and R18 where
R6 is the first breakpoint.