Fig 1

Until around 5 years ago the 'Industry Standard' sensor was the Phillips (Mullard) capacitive type (Fig 1).  This sensor is no longer manufactured which means sensors using this element which come in for repair may have to be scrapped and replaced with the new type.

                                                       Fig 2

Farm Electronics now use the Honeywell Sensor which also uses capacitance to measure RH.  (Fig 2)

The most popular RH sensor is the type HC-L2 (Fig 3) which gives a 0-10 volt proportional output of RH value. This sensor is supplied as standard with all current RH controllers. It can also retro fit all controllers with the 0-10 volt Phillips type sensor.

                                                       Fig 3

The HC-L2 sensor can also be used as a replacement for several other common type of sensor found in use in agriculture today. (Such as Tryac, Robydome, Stealth or Dolphine). Please contact us for advice.

HC-L2 RH Sensor Detail

                                                     Fig 4

For more demanding applications Farm Electronics manufacture the HC-H2 RH sensor (Fig 4).  This model uses a higher specification Honeywell sensor which can withstand a wetter, dirtier environment for much longer without losing accuracy or response.

HC-H2 RH Sensor Detail

All electronic RH sensors require periodic calibration checks to ensure accurate response. This can only be done in a 'workshop' environment and should never be attempted 'in situ'.

All Farm Electronics RH sensors use a waterproof plus connection on the sensor itself.