Figure III-2. Performance curves for two typical WSTP thermistors, as configured for high- temperature work during Leg 139. The two circuits allow nominal resolution of 0.1°C over a temperature range of about 0-200°C. The low-temperature thermistor (solid line) reads about 10k ohms at room temperature, while the high-temperature thermistor reads about 100k ohms at room temperature. The upper limit of the data logger is 30k ohms, making the low-temperature thermistor is usable over a temperature range of about 0-70°C, while the high-temperature thermistor is usable over a range of about 60-200°C. Overlap of the two thermistor ranges allows some intercalibration of the two sensors. Both thermistors were calibrated at the factory over their working ranges. Each thermistor is on a separate recorder circuit, with two data independent loggers run in a single recorder frame inside the WSTP. There is plenty of power in a standard WSTP battery pack to support two recorders.

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