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Anemometer / Wind Speed Sensor w/Wind Direction — Parallax Forums

Anemometer / Wind Speed Sensor w/Wind Direction

SavageCircuitsSavageCircuits Posts: 243
edited 2013-11-25 10:59 in Accessories
Does anyone know of a source of relatively inexpensive anemometers that also have the wind speed direction vane on them? I was surprised that 99% of what's on eBay seems to be hand held units and I need something for outdoors that I can interface to a Propeller chip.

Comments

  • WBA ConsultingWBA Consulting Posts: 2,934
    edited 2013-11-21 15:20
    I know a few people that have used this one from Spark fun, but not with Propellers.
    https://www.sparkfun.com/products/8942
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-11-21 15:23
    There's the Davis 7911. Reed switch for speed, ADC for direction.
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-22 12:29
    WBA Consulting wrote: »
    I know a few people that have used this one from Spark fun, but not with Propellers.
    https://www.sparkfun.com/products/8942

    It's out of stock, otherwise it's a very nice deal. Looks like they're supposed to be in just in time for Christmas. Maybe Santa will bring me one.
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-22 12:33
    Tracy Allen wrote: »
    There's the Davis 7911. Reed switch for speed, ADC for direction.

    An excellent consideration Tracy. If the SparkFun one isn't up to the reliability and quality I need I will try the Davis unit. I saw many of those (brand) on eBay. Looks solid.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2013-11-22 12:55
    I think it was RS_Jim who suggested using a magnetic encoder for wind direction. I like the idea since the sensor could be completely waterproofed and you wouldn't need to worry about keeping it dry.

    I think it would need to be calibrated since it's tough to get precisely linear output from from the magnet/sensor combo without precise alignment. Once calibrated you should be able to detect wind direction with a lot more precision (12-bit) than SparkFun's 4-bit precision.

    The same sensor could be used in an anemometer but it's kind of overkill for that application.

    I recently saw a weather station kit at a CostCo. I think it cost about the same as the one sold by SparkFun but included the electronics.
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-22 13:04
    Duane,

    I have looked at other options, however there are two issues I am faced with each option. The first is if I build a system, which I am not opposed to doing, then calibration becomes a requirement. I don't have the resources to do that at my command at this time, even I think, to get some reasonable accuracy. The second is the complete systems would need to be hacked, however most of what I have seen is wireless systems with a compact LCD controller with a blob on it. Not exactly the easiest things to hack.

    As for precision in wind speed and direction I would like the speed to be fairly accurate. However the direction could be 8 directions and I would be okay with that. Weather / environmental considerations is another reason I am shying away from a DIY setup. I know I could get both from an ultrasonic system but the cheapest I have seen is $1000.00+ and that is well outside what I want to spend.
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-22 13:14
    I did want to follow up and add that I appreciate all replies, comments and suggestions. This is a new area for me (weather monitoring on this scale) in terms of DIY stuff. Usually I am only looking at temperature and humidity.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2013-11-22 13:52
    Savage//Circuits wrote:
    calibration becomes a requirement. I don't have the resources to do that at my command at this time, even I think, to get some reasonable accuracy.
    Calibrating an anemometer is easy. I've done it many times. Wait for a calm day, mount the anemometer on your car roof, and find a straight, open stretch of highway with little traffic. Then drive at several fixed speeds, and record the output for each. Do it several times in each direction so you can compute an average. Then apply a least-squares curve fit to the results to get the slope of the velocity curve. (This is assuming that the mph vs. ppm is linear.) If the Y-intercept is non-zero, that means you had a side wind during testing and can just shift the curve down.

    -Phil
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-22 16:44
    Phil,

    I hadn't even considered the concept of using a car to do this, though finding a calm day here will be tricky. :blank: Last few days the wind is so fast it keeps blowing the garbage cans over. I may try it though at some point. Thanks for the idea.
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-11-23 19:03
    @Phil, Is the calibration different if you do it in your Lamborghini, say, or your Hummer? (Or bicycle?) I can appreciate that method, but it seems like you'd have to keep the anemometer well up out of the slip stream and gradients.

    Chris, here is another one.
    http://fascinatingelectronics.com/weatherinst.html
    I haven't tried them myself, but the interesting thing about the vane is that it uses a dual potentiometer to avoid dead bands.
  • FranklinFranklin Posts: 4,747
    edited 2013-11-23 20:54
    Tracy wrote:
    Chris, here is another one.
    http://fascinatingelectronics.com/weatherinst.html
    I haven't tried them myself, but the interesting thing about the vane is that it uses a dual potentiometer to avoid dead bands.
    I bought and built one of those and the only problem I had with it is the anemometer is fairly big and uses skate bearings (I think as I don't skate) and is slow to move at real low speeds. I have a Dallas setup I got many years ago and it spins in winds you can't even feel yet.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2013-11-24 00:41
    Tracy Allen wrote:
    @Phil, Is the calibration different if you do it in your Lamborghini, say, or your Hummer? (Or bicycle?) I can appreciate that method, but it seems like you'd have to keep the anemometer well up out of the slip stream and gradients.
    'Can't get up to force 9 on my bike, and there's no way to attach anything to the Lambo -- at least not until 2045 when it's paid off and I can drill some holes. The Hummer was taken in trade for the Lambo, so it has to be the '82 Benz diesel, I'm afraid. But yeah, you've got to mount the anemometer well above the roof.

    -Phil
  • RS_JimRS_Jim Posts: 1,764
    edited 2013-11-24 06:00
    Chris,
    Check out this guy, he has some great how to build instructions on a wx station. If you use any of his ideas, be sure to give him credit as he does get rather anoyed with people taking credit for his ideas.
    Jim
    http://vwlowen.co.uk/picaxe/weather-station/weather-station.htm
  • SavageCircuitsSavageCircuits Posts: 243
    edited 2013-11-25 10:59
    Once again thanks for all the feedback. I am looking into all options.
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