resistive humidity sensor wisdom

Discussion in 'The Projects Forum' started by pibeans, Mar 31, 2013.

  1. pibeans

    Thread Starter New Member

    Jan 11, 2013
    I have canniballised an old Oregon remote unit to re-use the humidity sensor - which I assume from appearances is resistive.

    (I have DHT11 and DHT22 sensors to hand but distrust them)

    The project will ultimately - probably - be a wireless module with ATTINY and an RPI "base-station".

    The accepted wisdom for resistive RH sensors is to excite them with AC to avoid polarising the sensor. But the overhead of an AC input and rectification to a simple measurement is a pain.

    So: is it acceptable to activate and sample the sensor for a short period intermittently (a few s every few m)? Possibly/probably reversing the polarity of the supply from one sample to the next?

    TIA / piBeans