My Outdoor Motion Humidity Sensor

  • Admin

    Ok, finally has some time to put together my first outdoor sensor.

    It will be used to increase outdoor-light level when someone moves around our house. Also reports temperature and humidity level. Got 24V where it will be placed.


    Final test:

    And the sketch:

  • which power supply method are you using?
    Battery, or AC voltage? looks like interesting

  • Admin

    I have added a AC->AC converter to reduce the 24VAC (i have for led-lightning) to something 12V-ish which is feed to the Arduino.

  • Well, this looks good. but i still confused.
    arduino only support VDC right? not VAC. mind to explain how you supply arduino with VAC?

    thanks @hek

  • Admin


    No wonder you are confused.
    Of course I meant DC->DC converter and 24VDC.

  • Hero Member

    I have a pretty good experience using the motion sensor outdoors. Been running mine since October on 2xAA batteries (no regulator) and the damn thing is still alive despite cold weather and being triggered 4-5 times a day (not counting the false positives). What is sort of tricky is avoiding is the false positives, e.g. magpies exploring the porch (I have the sensor at about knee level), sunlight rising and falling quickly on a day with spotty clouds and fireworks at New Years Eve. Bottom line, avoid incoming direct light at all cost and put it in a shaded place. Now it is possible that one might filter out those false positives using the sensitivity setting, I don't really know. I also suspect that having dry leaves and stuff get right up close and blow by the sensor is a source of some false positives.

  • Contest Winner

    @bjornhallberg If the reading is analog, you perhaps could "weight" the sample. A relatively big change rules out sunlight cycles and perhaps even clouds.
    EDIT: See now that the motion sensor is digital. So that would not be possible. But perhaps if combined with a light sensor.

  • Admin


    I wlll put it on the eaves (takfot) without any direct sunlight.

  • Hero Member

    @hek I noticed you are sleeping the sensor? Is the 24v not constant?

  • Admin


    Just an old habit...

  • Hero Member

    @hek Ah ok. I thought you might be up to something. :-)

  • @hek Thanks for the clarification :+1:

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