Visual rain sensor — so you never have to look outside

Now you can find out how hard it is raining outside without leaving the confines of your mancave/womancave. Pictured above is the sensor portion of what [Frapedia] calls his visual rain sensor.

Most rain gauges just use a graduated cylinder to capture water as it falls from the sky. That will give you a reasonably accurate measure of how much it rained, but it tells you nothing about how hard it rained. The measurement made here is based on sound. The harder it rains, the lounder the sound will be from water hitting an up-turned metal bowl. The unit above turns the system on when water bridges the traces, then a microphone is used to monitor the sound from the bowl. This is visualized by a VU-meter chip on a column of LEDs mounted inside the house.

After the break you can see the project box that houses the status display. We say it’s too small an needs to be replaced with a much larger LED meter.

Comments

  1. Chris says:

    In Vancouver, the virtual rain sensor is just a switch permanently stuck in the “on” position.

  2. mancamp2012 says:

    Yes I feel like you are going to get a lot of false positives as well as a long longer effect many hours after the rain stopped.

  3. draeath says:

    The sensor shown in the first picture is pretty novel, but you are going to have corrosion problems. Rainwater is going to contain all sorts of other stuff in it depending on atmospheric conditions, not to mention being exposed to the open air.

    Just the water and air is going to oxidize the thing to uselessness.

  4. HAD says:

    The unit above turns the system on when water or a leaf or a slug or anything conductive bridges the traces.

  5. fartface says:

    Rain sensors are easy. Rain sensors that last years not so much.

    If you have a laser cutter, some thin stainless can be cut into those fingers and then potted in a UV stable epoxy to make one that will last more than a few weeks like the copper etched board.

    Thinner lines deliver higher sensitivity, We had one that could detect a light mist.

  6. fightcube says:

    Two words: Gold Plating

  7. coyoteboy says:

    Gold still tarnishes with chemicals found in rain (thanks to pollution). Might last a lot longer though. Still, this is only his trigger and can easily be cleaned periodically.

    the method used in virtually every vehicle made with auto wipers works nicely though and is pretty much impervious to problems – reflected light intensity – droplets on the glass screen reflect a different amount of light to dry glass. Can be IR too, easy make with phototransistor and an LED.

    • ino says:

      Indeed.
      It’s the same system used to detect droplets of water forming inside sampling tubes in a gas analyzer.
      Whatever the content of the gas, it can not affect the system.

  8. No speaker?

  9. AussieTech says:

    Exposed solder joints = trouble.

    The idea of an acoustic rain integrometer is a neat one that has been under-explored. Properly calibrated it has the potential to record mass-flow and provide more information about rainfall intensity than simply counting volume with a tipping bucket (and potentially more weather-proof).

    @coyoteboy – thank you for that tip.

    • Cyril says:

      A tipping bucket sensor DOES effectively give you intensity, after all the data is logged with respect to time.

      The only way this could be more weather-proof (than a tipping bucket) is if you made no attempt to weather-proof the tipping bucket. There is no requirement to have exposed anything with a tipping bucket.

      I cannot see a way to calibrate this effectively as the method is open to noise from wind and wind-blown objects like leaves and debris hitting the dish.

      Granted a tipping bucket is inherently inaccurate due to its mechanical nature and the size of the bucket and feeder funnel but I can see the tipping bucket would be (at least) an order of magnitude more accurate than this method.

  10. Chetchez says:

    Two words: Leak Frog.

  11. Ren says:

    disdrometer

  12. wholostwhat says:

    How about the type of rain sensor used in car windows? A beam of light is shone through the glass and the amount which hits the sensor is dependant upon how much is scattered due to raindrops on the glass. That can be totally corrosion resistant as the transmitter and receiver can be behind the glass in an enclosed space.

  13. BD says:

    “Most rain gauges just use a graduated cylinder to capture water as it falls from the sky. That will give you a reasonably accurate measure of how much it rained, but it tells you nothing about how hard it rained.”

    Couldn’t you just measure how fast the graduated cylinder fills up to determine how ‘hard’ it rained?

  14. Ray says:

    You should also check out wireless rain sensors available in a lot of retail stores. Here is one example:

    The way it works is by using balanced bar (like a teeter-totter) inside the sensor to sense rain. The heavier the rain is, the more frequent the bar will switch back and forth. The frequency is detected by a reed and sent to a reader through a RF transmitter. I found an animation that shows this nicely:

  15. Ray says:

    You should also check out the wireless rain sensors available in many retail stores, like this one:

    The way it works is by using a balanced bar (kind of like a teeter-totter) to detect rain. The heavier the rain is, the more often the bar will switch back and forth. The frequency of the switching is detected by a reed sensor, and sent to a read through an RF transmitter. This animation is useful at explaining the principle:

  16. Drone says:

    Hydreon Optical Rain Sensor – Model RG-11

    http://www.rainsensors.com/

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