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Enabling better global research outcomes in soil, plant & environmental monitoring.

Apogee Thermistors

The ST-100 is a high accuracy thermistor (± 0.1 C from 0 to 70 C), mounted in a waterproof housing, designed for continuous measurement of air, soil, or water.

The ST-110 is a high accuracy thermistor (± 0.1 C from -40 to 60 C) designed to minimize solar load and thermal conduction. White heat shrink is used on the cable behind the thermistor to reduce solar load. Constantan wire is used to minimize thermal conduction down the wire towards the thermistor. The ST-110 is designed to make air temperature measurements in Apogee’s TS-100 Aspirated Radiation Shield and can be used in static, multi-plate shields from other companies as well.

The ST-200 is an accurate (± 0.2 C from 0 to 70 C) fine wire (0.45 mm tip, 0.15 mm wire) thermistor designed for measurement of delicate surfaces or small samples with a fast response time, less than 1 second.

ST-100
Thermistor
ST-110
Thermistor
ST-200
Thermistor
Measurement Range -60 to 80 C -60 to 80 C -60 to 80 C
Measurement Uncertainty 0.1 C (0 to 70 C), 0.2 C (-25 to 0 C), 0.4 (from -50 to -25 C) 0.1 C (0 to 70 C), 0.15 C (-50 to 0 C) 0.2 C (0 to 70 C), 0.4 C (-50 to 0 C)
Long-term Drift (Non-stability) Less than 0.02 C per year Less than 0.02 C per year Less than 0.02 C per year
Time Constant (time for detector signal to reach 63 % following a step change) 32 s 7 s 2 s
Self-heating Less than 0.01 C (typical, assuming pulsed excitation of 2.5 V DC) Less than 0.01 C (typical, assuming pulsed excitation of 2.5 V DC) Less than 0.01 C (typical, assuming pulsed excitation of 2.5 V DC)
Operating Environment -60 to 80 C; 0 to 100 % relative humidity -60 to 80 C; 0 to 100 % relative humidity -60 to 80 C; 0 to 100 % relative humidity
Resistance at 0 C
Input Voltage Requirement 2.5 V DC excitation (recommended) 2.5 V DC excitation (recommended) 2.5 V DC excitation (recommended)
Output Voltage Requirement 0 to 2.5 V DC (assuming input excitation of 2.5 V DC) 0 to 2.5 V DC (assuming input excitation of 2.5 V DC) 0 to 2.5 V DC (assuming input excitation of 2.5 V DC)
Current Draw 0.1 mA DC at 70 C (maximum, with steady excitation of 2.5 V DC) 0.1 mA DC at 70 C (maximum, with steady excitation of 2.5 V DC) 0.1 mA DC at 70 C (maximum, with steady excitation of 2.5 V DC)
Dimensions 100 mm length, 6 mm diameter 80 mm length, 4 mm diameter 25 mm length, 1 mm diameter
Mass 60 g 60 g 60 g