A range of digital and analog temperature sensors are available for measuring temperatures in air, soil, soil surface, leaf surface or water.
TDC digital temperature sensor uses a miniature diode connected transistor mounted at the end of a thin wall 4mm diametre stainless steel tube protruding from the approximate 25 mm diametre. electronics housing. The electronics consist of. MONITOR SENSORS high accuracy voltage to frequency converter having excellent thermal stability characteristics and a calibration of better than +/- 0.2 oC over the range of - 10 oC to
+ 50 oC.
Software calibration gives a resolutian of 0.1 oC over a 6 minute integration period, which is the standard temperature integration period on MONITOR SENSORS data loggers. Special calibrations can be provided to give .03oC resolution over 6 minute integration periods, and + 0.1oC accuracy over the temperature range -10 to +50oC.
The digital units have square wave outputs with a nominal frequency change of 0.1 Hz per degree centigrade from –30 oC to+70 oC and the frequency at 20 oC is around 5 Hz. With a 6 minute integration a resolution of 0.1 oC is obtainable. The accuracy of measurement is +/- 0.2 oC over the range. Sensors with the high speed (HS) option have a nominal frequency of 1 kHz at 0 oC. Sensors are supplied with individual calibration certificates to enable software conversion to engineering units, as for example in the Algorithm lists of MONITOR SENSORS data loggers.
The analog versions give a voltage output of approximately – 40 mV per degree centigrade with O oC being approximately 3.4 volts. Measurement over the range of –15 oC to +70 oC will have an accuracy of 0.2 oC.
Both digital and analog sensors are designed to run from an unregulated D.C. power source of 4.5 to 7 volts.
Model TDC-01A: A digital sensor for air temperature.
Model TA-01A: An analog sensor for air temperature.
The two designs measure air temperature or may be used as wet bulb temperature sensors which in combination with air temperature provides relative humidity by calculation. These sensors mount in a meteorological shelter and are fitted with 600mm of 3 core cable.
Model TDC-02S: A digital sensor for soil temperature.
Model TA-02S: An analog sensor for soil temperature.
These two sensors are to be buried in the soil at an appropriate depth and are supplied with 4 metres of 3 core cab1e.