The frost sensor works on the principle of conductivity between three electrodes arranged on a flat surface.
A 100Ω resistor is embedded beneath the sensor surface. The 5W resistor is used to heat the sensor. The temperature of the measuring surface rises to approximately 20-30°C above the air temperature.
The heater can record the total duration of the precipitation event (dew + rain) or just the beginning and end of the rain.
To locate the frost, the sensor has an additional thermistor
The operation of the heater leads to rapid drying of the sensor surface, thus reducing the latency time to a minimum.
The sensor should be mounted on a truss at an angle of 30-40° to detect rain, drain excess water from the surface, and assist in rapid drying of the sensor after the rain has stopped.
It works as an 'ON' or 'OFF' device.
The sensitive part of the sensor consists of three carbon electrodes separated by waterproof resin. This calibrates a 1 mm diameter droplet of distilled water.
Mode one signal produces output change from 0 V to 1.4 V over.
