MEASUREMENT AND CONTROL OF TEMPERATURE 



♦ 300 



-300 



Figure 29.6 Practical circuit for measurement of temperature by a thermistor — 

 mains-operated unit. Thermistor type: 100 k^i at 20°C; suitable meter, 50 jjlA 

 in series with 50 k^. The selector switch covers the ranges 1 5-20, 20-30, 



30-50, and 50-1 00°C 



H^ \— jpW^A- 



200 ft 



Figure 29. 7 Practical circuit for measurement of temperature by a thermistor — 

 portable battery-operated unit. Thermistor type: 2 kQ at 20°C. In addition 

 to three temperature ranges, a switch position is incorporated for setting 

 the bridge voltage to a standard level by means of the variable resistance 



392 



