The Telecontrolli capacitive rain sensor detect with precision and effectiveness the precipitation rate, the current precipitation intensity and its end, avoiding false positives which can cause inappropriate operations (objects such as dirt or other particles that in preexisting optical sensors cause a reflection mimicking the one of rain and limit its effectiveness in rapidly responding to light rain).
Capacitive sensing is a technology based on the change in capacity determined by the change of the dielectric constant of the material separating the electrical conductors (plates) of the capacitor following the action of external agents.
Capacitive sensing is becoming a popular technology to replace optical detection methods and mechanical designs for applications like proximity/gesture detection, material analysis and rain/humidity detection, because it offers more reliable and accurate measurements than optical ones.
The Telecontrolli capacitive rain sensor shows higher levels of sensitivity and reliability (it is able to detect light rain, fog and humidity) and of noise immunity than other sensors on the market; it takes up a small volume (about 35 x 30 x 0.7 mm), his power comsumption is next to zero (it’s a passive sensor) and it is economically competitive on the market.
The sensor has IDT electrodes on one side of the alumina substrate, while a resistive heater and a temperature sensor are placed on the opposite side. The rain sensitive area, which in dry conditions assumes the nominal value of 100pF. Moreover in presence of the rain, the capacitance goes to high values compared to dry conditions and the ratio changing is over 300%. (See Rain Sensor Datasheet and Application Note for futher informations)
The integral and configurable heater is provided to ensure that the detection surface dries quickly, protecting the surface from fog, condensed moisture and frost. It also can be disabled when power consumption is critical.
The alumina substrate and the glass sensitive layer makes the sensor immune to water and moisture absorption, ensuring high resistance and long duration.
Moreover, thanks to the thermal conductivity of the ceramic, the heat emitted by the heater on the back of the sensor is immediately transferred to the upper surface, making the sensor more sensitive than other technologies.
Furthermore, while resistive rain sensors are sensible to corrosion and contamination, the Telecontrolli capacitive rain sensor doesn't suffer from these disadvantages and it is the ideal sensor for any type of application: irrigation systems for agriculture, wiper systems for the automotive industry, weather stations, applications for home and building automation.
TALK ABOUT TELECONTROLLI CAPACITIVE RAIN SENSOR:
- PRINTED FILMS: MATERIALS SCIENCE AND APPLICATIONS IN SENSORS, ELECTRONICS AND PHOTONICS by Maria Prudenziati & Jacob Hormadaly - Woodhead Publishing;
- DIY ELECTRONICS:
Arduino Rain Sensor Tutorial: http://www.avdweb.nl/arduino/hardware-interfacing/rain-detector.html
Maker Project: Peggy, an Arduino rain tracker http://www.instructables.com/id/Peggy-Arduino-Portable-RF-Rain-Tracker/