Wind Sensor Rev. P out in the open?

Questions about Modern Device and JeeLabs Sensors
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hmjswt
Posts: 1
Joined: Tue Mar 13, 2018 5:47 am

Wind Sensor Rev. P out in the open?

Post by hmjswt » Tue Mar 13, 2018 5:52 am

Hallo,

I have bought the Wind Sensor Rev. P and are awaiting its arrival.
But now I am wondering, can I put it out in the rain?
I want to use it as part of a DIY weather station.
So, can I put it outside?

Greetings from the Netherlands.
Henk Siewert

paul
Site Admin
Posts: 705
Joined: Mon May 12, 2008 4:19 pm

Re: Wind Sensor Rev. P out in the open?

Post by paul » Tue Mar 13, 2018 3:36 pm

Henk,

You should obviously cover the electronics package with something waterproof. My guess is that the sensing elements may not last too long though, out in the weather. Water plus electricity equals electrolytic reactions and corrosion. You could try spraying the sensing elements with some kind of clear coat, thinner would be better - for not changing the sensor's output, but thicker would be better for preserving the sensor from the weather.

Sorry we can't give you more guidance. We'll spray paint some sensors with clear and see how much it changes the curves.

Paul

jbeale1
Posts: 1
Joined: Thu Sep 20, 2018 12:12 pm

Re: Wind Sensor Rev. P out in the open?

Post by jbeale1 » Thu Sep 20, 2018 12:33 pm

I have the same question about Wind Sensor rev. P. I assume that I will need to put some kind of roof over it so it doesn't see direct rain (apart from electrochemical corrosion issues, a raindrop hitting the thermistor would obviously completely invalidate the sensor reading). I have had good luck in the past with bare PCBs under a roof overhang but otherwise exposed to weather, that were simply painted with two coats of exterior latex paint. I had a Raspberry Pi camera board mounted unhoused and exposed like that, powered 24/7 for over a year without any issues, apart from occasional spider webs in front of it. Make sure the paint dries completely before applying power. Of course, painting the actual cantilevered sensor elements would insulate them and greatly change the calibration. For accuracy I think you also need to calibrate at different humidity levels because both thermal conductivity and specific heat of air is strongly affected by the amount of water vapor in the air (absolute humidity). When it is cold, this is a smaller factor because the air doesn't carry much water. On hot days, air can hold a lot of water. I assume I can't post a link here, but do a search for "specific heat of moist air" to see what I am talking about.

paul
Site Admin
Posts: 705
Joined: Mon May 12, 2008 4:19 pm

Re: Wind Sensor Rev. P out in the open?

Post by paul » Fri Sep 21, 2018 12:09 pm

Henk,

You have two options. As stated above you could coat the board with something. We've had good luck with epoxy, just flowing it onto the board, over the components. (but not the thermistors).
If you are going to coat the sensors, use something thinner like spray coat of clear polyurethane or similar.

The second option is to cut off the "sensing prong" in between the double headers. Tin snips work well. Then wire it back together and put the electronics in a waterproof box. You could also coat the electronics too if you wish.

Paul Badger
Modern Device

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