Never Let Your Christmas Tree Run Dry, With Added Ultrasound

Winter in the parts of the Northern Hemisphere for which observing Christmas includes bringing half a forest into the house should really be divided into two seasons. No-spruce-needles-in-the-carpet season, and spruce-needles-doggedly-clinging-to-the-carpet season. Evergreen trees were not designed for indoor use, and for a hapless householder to stand any chance of keeping those needles on the branches there has to be a significant amount of attention paid to the level of the water keeping the tree hydrated.

[Evan] has paid that attention to the problem of Christmas tree hydration, and to address the shortcomings of earlier designs has come up with a low water warning using an ultrasonic rangefinder. Where previous sensor attempts based on conductive probes succumbed to corrosion or dirt build-up, this one has no contact between sensor and water.

Behind the rangefinder is a CHIP board, whose software sends a text message to his phone when the water level gets a bit low. All the software is available in the linked GitHub page, so should you wish to make your tree safe from thirst, you too can give it a try.

SMS texts are a good way to alert a tree owner, but we quite like the sensor that used the tree lights instead.

10 thoughts on “Never Let Your Christmas Tree Run Dry, With Added Ultrasound

    1. ^^this and any variation of ths is easier to do and use, with the added bonus of not needing batteries or a phone.
      Having said. that it probably has a thousand and one way more useful applications, except for the batteries and the phone thing

      1. It’s learning. No waste of time at all. Several hundred more things that can be tried and therein lies the bulk of the hacking. Just look beyond the trees. Hacking is plural not singular. Tons more to try yet.

        Tried a polaroid unit back in the day. Mousetrap, think they could hear it. Feeding bats I KNOW they could hear it because left the area. Cats, no or ignore it. Too expensive to detect humans for light and door control plus false triggering problems but good for an unexpected light show during any thunderstorm. Good enough for model train enthusiasts. PRF too low for slot car racing. Did not have the arduino or raspi to interface it to back then and that should make it much more fun now.

  1. Or you could use an inverted storage bottle + tube so that as the level decreases, air is allowed in and it refills itself.

    All of this is moot once the pets discover the new play-toy though…

  2. I saw in a book once where someone did this by strapping two pieces of conductive foil on both sides of a soluable pill. It’d conduct electricity if the pill got wet. It’s kind of the opposite.

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