desired temperature range, and pb is a constant for a particular 
type of thermistor as previously defined. This error function was 
obtained using the original empirical equation as the resistance 
of the thermistor in the circuit shown in figure B4. The predic- 
ted error (fig. B7) for a 10°C range is seen to be 0.004°C. This 
shows good agreement with our computations, since figure B6 
gives an error of +0.0045 °C for the optimum parameters (7 = 
2670 ohms) over a 10°C range. If a 20°C range is required, fig- 
ure B7 indicates that the maximum departure from linearity would 
be approximately 0.042°C. 
CONCLUSIONS AND RECOMMENDATIONS 
A thermistor temperature bridge, linear to + 0.05 percent 
over a 10°C range, was obtained. This is the result of combining 
A. T. Burke's expression for the optimum series resistor with 
an asymmetric half-bridge circuit as described by Kaufman. * 
Both the method for linearizing and the circuit itself are readily 
adaptable to the fabrication of interchangeable, precision tem- 
perature probes. The results given here are based on computa- 
tions, except for the original calibration of the thermistors. 
If it is desired to design a linear temperature bridge using 
thermistors, it is recommended that reference should first be 
made to eq. (B16) which is plotted for a particular type of therm- 
istor in figure 7. Here one can get an idea of the degree of 
linearity that can be expected once the temperature range is 
fixed. The value of the optimum linearizing series resistor can 
be obtained from eq. (B15). Reference may also be made to 
Beakley's method, ** eq. (B3a). 
*Reference Bl, page 55 
**Reference B3, page 55 
