Davis VP 2 Anemometer

[Randall75]

Thanks Blic


 

[elagache]

Hi Randall and WeatherCat fans,

OK I went out in a blizzard and I mean a blizzard and exchanged out the anemometer all is now working
And Edouard 8 inches of snow, zero tonight 1-3 more tomorrow then on Tuesday 13 below zero actual temps
with wind chill around 40-50 below zero are you sure you want some of this cause it is cold 

Glad you are at least back up and running.

Believe it or not, there is that "R" word in our forecast for late next week . . .   So far it doesn't seem like the high-pressure is disappearing like it should, but perhaps there will be a change bringing the jet stream closer to its normal trajectory.  That would go a long way toward getting the rest of the United States out of the deep-freeze.

Cheers, Edouard 

[ColdnFrosty]

I installed a new VP2 a couple weeks ago to replace the very old WMII.  The wind cups on the new VP2 would not stay put due to stripped threads, but Davis sent me a new one right away. I noticed a horizontal metal bar glued inside the replacement part, something that was not in the cups that came with the station.  Anyone know what the bar is for? Thanks.

[KeithC]

Maybe if you had a photo or a more detailed description, but from your above description I wouldn't venture to guess. I would say this, though: If it wasn't on the original part, then it might very well be that they sent you the wrong part. Does it interfere with installation? Can you snap a pic of this metal bar?

[ColdnFrosty]

It is the correct part. They sell a 7903L for stations 2002 and earlier. And a 7509L for stations 2003 and later.

"Replacement wind cups, large with horizontal magnet, for Vantage Pro2 anemometers 2003 and later. Outside cup diameter: 1.5" (38.1 mm).
For anemometers sold before 2003, see #07903L Wind Cups, Large (Anemometers 2002 and earlier)."

So apparently its a magnet, but I have no idea what it's purpose it.  The original cups did not have one. And the 2002 and earlier model has a vertical magnet rather than a horizontal magnet.

"Replacement wind cups, large with vertical magnet, for Vantage Pro2 anemometers 2002 and earlier. Outside cup diameter: 1.5" / 38.1 mm.
For anemometers sold after 2002, see #07905L Large Wind Cups."

[KeithC]

It sounds like maybe the original cups were older model while the replacements are correct. I don't know. The magnet is probably how the sensor detects one complete revolution of the cups. Timing that revolution results in a wind speed. Sorry for the guesstimations; we all prefer expert answers.

[Randall75]

Hi coldandfrosty
 The best thing to do is call Davis support


cheers


 

[Doc]

  Well, here we are at the beginning of Indiana's severe weather season (now till september)  and I'm working on my weather station to make sure it's running OK.  Found out that I can buy fresh Duracell 123 batteries through Amazon in twelve packs for less than I could buy a single battery from the local Radio Shack (where more than half of the batteries sold are already dead I might add, always have them checked before you buy them).

That said, I have been working on various anemometers for the last few months and there are three basic sensor types I have seen, Davis generally uses a magnet rotating with the cups and a reed switch to generate a open/closed circuit which the sensor unit then counts to make the wind speed calculations.  These magnetic reed switches are pretty easy to make and don't require much to make them work but a good strong magnet,  Davis has used a vertical rod magnet and a horizontal bar magnet in their anemometers.  I think they are using the horizontal bar magnet now because the vertical rod magnet would often pass the switch without activating it causing an incorrect reading.  The horizontal magnet spends more time per pass over the switch and thus allows the switch to activate most of the time.  Either will work I have learned, just you may not always get a reading due to an occasional miss during high winds.  The error is not a huge one and you probably would never notice it in your readings.

The two other forms that I have seen are the voltage generator and the Hall Sensor, both are hardware intensive, can be very accurate and are used in a lot of commercial sensors.  But they are also quite expensive.  I have a Hall Sensor that I'm trying to make into a relay switched output for the Davis, so far, no luck getting it to work so far.  I want to use this one on my mobile station where they do want wind data reported.  The Davis anemometers don't like being hit by trees when driving and tend to leave their bits and pieces behind after an encounter with a tree or other unkind thing hitting them.  The Hall Sensor I have is heavy duty metal and can be pole mounted for a heavy duty mount.  It takes 12v to power it, and puts out a pulse from an NPN circuit on each revolution, I have a circuit that will take that output and supposedly will trigger a reed switch relay, but so far nothing has worked.  Still working on it.  It's been interesting playing with these though.

Good Luck

Doc

[elagache]

Hi Doc and WeatherCat tinkerers,

Found out that I can buy fresh Duracell 123 batteries through Amazon in twelve packs for less than I could buy a single battery from the local Radio Shack.

  . . . . Awe shucks!  Anuther thing that's cheaper at Amazon!  If this keeps up, I'll end up buying virtually everything at Amazon and my trusty wagon won't have anything to do!! . . . 

That said, I have been working on various anemometers for the last few months and there are three basic sensor types I have seen
. . . . .
Still working on it.  It's been interesting playing with these though.

Thanks for the quick explanation of how these devices work! 

I hadn't thought about the trade-offs of say the magnetic counter versus something like a hall-effect sensor.  Definitely food for thought!

Cheers, Edouard 

[Blicj11]

always have them checked before you buy them

Thanks for this tip - I hadn't thought of that.

[Doc]

Yep check your batteries, the majority of the less popular sizes will be dead in the store! 

Back to working on a mobile weather station again, should be fun, but I need to waterproof the wireless board first.  Fun.  I'm using the Digitar Weather Master sensors with a Davis Weather Monitor III this time, should be an interesting build.  The rain bucket has no moving parts to break like the Davis.  Digitar was the company that became Davis.  Most of their sensors are compatible. they just have different connectors.

Doc

[KeithC]

That's pretty cool, Doc!

I was contemplating giving that a try with a BeagleBone Black ( http://beagleboard.org ) -- maybe a direct-to-website FTP from the field. But there's four problems holding me back: 1) I'm still too ignorant in electronics and; 2) I'm still too ignorant with BeagleBone; 3) I'm still too ignorant :-D; and 4) I don't have enough time to educate away my ignorance.

So I'm glad you're out there making it happen. Can't wait to see what you come up with.

[Bull Winkus]

Hey Doc! Quite an interesting project you've got going there. Keep us posted as it develops. Some pictures would help too, if you should find the time.

You probably already know this, but I thought I'd mention it since you haven't. Hall effect sensors output millivolts. Too weak to activate anything unless it is run through amplification.

Here's a link to a very informative page about Hall effect.

http://en.wikipedia.org/wiki/Hall_effect

[Doc]

 

Well so far I have had to put my mobile station on hold for a while due to financial obligations.  However, I have made a watertight box for the wireless outdoor electronics now, a plastic ammo type container with disk magnets on the bottom so it stays put in the truck bed.  The sensors have been a problem, the passive sensors for temp and barometer are fine and don't need anything special for them to work, they also can be magnetically mounted to the sidewall of the truck bed and will remain out of the way on their own shelf.  The old Digitar rain bucket shouldn't be much of a problem either. 

Then the most critical and most difficult sensors are again the anemometers     I have tried several with the magnetic reed switch configuration that works with the Davis system, all work and all are within an acceptable speed calculation.  The best one so far is a magnetically mounted set of cups on the roof, these came with a bicycle speedometer for a display and work very well, they also work OK with the Davis setup.  When they are mounted in the center of the truck roof they work well and they hold up against the occasional hit by a tree, usually by falling off into the truck bed.

Most of the rest suffer from mounting issues and destruction by the occasional tree hit. 

The chinese military style anemometer works best structurally against being hit by trees, and is very smooth operationally.  I is flange mounted to a pipe that must be bolted to the floor of the truck bed.  I've been working on a quick mount that can be set up and taken down easily as needed, the initial tests have been very good.  The main problem is this is also the sensor with the Hall effect sensor and I have been having a hellish time trying to build a working interface to the Davis system.  I just need it to switch a reed relay on and off.  The reed relay works with the Davis system just fine, it's just getting it to trigger and that hasn't been working out well.  So it's on hold for now till I can research some more circuitry.

What would be cool in the future would be a version of Weather Cat for the iPad (cellular versions) so that the mobile weather station could be interfaced with it and display the weather data as well as uploading it to the internet by the cellular link.  (hinting and very wishful thinking I'm afraid    )  Ah Well, Someday!

Have fun, watch out for sever weather!

Doc

[elagache]

Hi Doc and WeatherCat mobile weather watchers,

Well, my trusty wagon's "brand new engine" is being dismantled once more to fix the gasket leaks so mobile weather watching won't be happening for me for a while . . . . .

However, I do like to daydream! 

Well so far I have had to put my mobile station on hold for a while due to financial obligations.

Ditto! 

Most of the rest suffer from mounting issues and destruction by the occasional tree hit. 

You don't say!! 

That may prove to be an especially difficult nut to not crack! 

What would be cool in the future would be a version of Weather Cat for the iPad (cellular versions) so that the mobile weather station could be interfaced with it and display the weather data as well as uploading it to the internet by the cellular link.  (hinting and very wishful thinking I'm afraid    )  Ah Well, Someday!

Well, I agree it is a someday, but I suspect the problem isn't the aspirations of our fearless leader (who has a certain weakness toward wandering the Scottish wilderness with his Land-Rover and caravan,) but the lack of a standardized mobile weather station.  If someone were to come up with a a mobile station like the Kestrel stations which could talk to an iOS device and Apple would make developing for OS-X and iOS in tandem easier, . . . . . I suspect Stu would find it really hard to resist!

However, fortunately for Stu, no such portable station yet exists. .  . . .  otherwise Stu might get himself into serious mischief!

Cheers, Edouard