Back to

Sensor hang when raining

Hello, every time the humidity is near 100% or over (I don’t understand how It can go over 100%) my sensor hang I have to switch-off & ON, to restore working. How to fix this because it’s very annoying in autumn and winter season.
I’m using 3D Printed Prototype enclosure from Martin Hess. The sensor is in a balcony protected from the rain.
Merry Christmas to all

Do you see signs of condensed moisture inside the enclosure or on any of the boards. even a tiny amount can cause problems.
If so, then you need to look at protecting the kit during the highly humid conditions. Try changing the location.

Dear Bryn, thanks for answering my question and trying to help me with my problem. I thought that this forum was no longer read and that this project was going to be abandoned.

Yes on the sensor there are fine particles, the 3D box I use is in the open air. It would take a protective case suitable for the outdoors.
Okay for the change of location, but when it rains with a lot of wind or there is fog, difficult to protect it.
I was thinking of putting a very fine mosquito-type fabric to protect the sensors or simply a very honeycomb foam. Or maybe this fabric that we find on the microphone capsules. But will the measurements always be realistic?

Kind regards.

Ok here is an insight I have from something else I am working on, concerning gas sensors. In that context, the manufacturer I was looking at recommended using a gas permeable Teflon shield around the gas sensor. Now, applied to your situation, perhaps such a thing might also help to keep out condensed water while allowing air through. I have seen some similar shields in a few of the enclosure designs. Some of them use a kind of fine mesh, like you would see used as a lint filter in your washing machine. The key point (for my gas sensor) behind selection of Teflon material is that some plastics absorb or emit gases that would invalidate readings. But the standard SCK contains only eCO2/VOC sensor so perhaps it’s not an issue for you.
I have not yet researched where one might procure a gas permeable Teflon shield, but the first place I would look is 3M, also Mouser perhaps. Here is one I found that makes the stuff:

[Hydrophobic ePTFE Membrane - OEM Membranes and Devices - Cobetterfiltration]

A further random thought. A COVID mask is made from non woven material, maybe it’s not Teflon, but it could work as a trial of concept, and it’s readily available.

Also would need to ensure that the dust sensor is not inside the shield, and check that humidity sensor readings are unaffected too.

I have to say at one point I harbored the same thoughts. But recent offline discourse with Fablab personnel yield the simpler explanation they are simply inundated with work. So my response to you is my way to help out the only way I can with their workload. It’s a community project after all, where some of the work is by volunteers.

Thanks Bryn for all the ideas and advice. I found a ePTFE membrane from the big Chinese website, but it’s very expensive for 2cm of it. I will try to retrieve the filter from a 3M FP3 mask and do a test to see if the reading is not altered.
I can understand that they are indeed inundated with work. In this case, an announcement message in the forum with the situation will avoid misunderstandings . Which makes me say that the majority of dead kits certainly come from owners who think the project has no follow-up.
For me the use is mainly for my amateur radio hobby and to know the pollution in my living area (being close to a highway)
Maybe you can also tell me why there is a difference between the barometric pressure of the kit and the actual pressure. I have noticed from the start a difference of about 40hPa
Thanks for your time and my kind regards to you.

I cannot say for certain. But concerning Barometric pressure the sensor reads the exact pressure at that spot in real time. Unless you live near the sea, it will almost never agree with the weather bureau or the news report. That is because they adjust the pressure readings to an equivalent value for mean sea level.
Barometric pressure reduces with altitude (remember an old style altimeter on a small aircraft is based on a barometer).
If the seaside is near where you live, you could travel there with your SCK in hand running on battery and see what reading your get.
There is a formula you can use to adjust a real barometric reading to mean sea level but in this coffee shop It’s not handy right now.
You could add a GPS to your SCK to get exact altitude, or you can read it from a topographic map, or you can google it.
I hope this helps, cheers

Hi Bryn,
Thanks again for your time and explanations. It is all the same strange because even with the old barometer of the grandmother or my weather station DNT, the pressure is identical to what is announced on the weather sites like I think it would take a calibration to have real and consistent values.
This project was ambitious, but the end result is disappointing. I think I’ll end up like thousands of others with a ghost kit.
Kind regards and thanks again.

You Grandfathers old Barometer is based upon the principle of fixed air pressure inside a metal can being compared with the outside air pressure. This causes metal lid of the can to deform more or less. A needle touching the surface moves with the lid and is linked mechanically to the needle. The mechanical arrangement allows the altitude to be compensated to account for the difference with mean sea level pressure. There is usually a knurled little knob on the front of a barometer for this purpose. I have no knowledge of weather station DNT.
The electronic barometer inside SCK/SCS works on different principle (read the specification). but an altitude compensation can be made in the programming library for the device.
If you include a GPS device (such as Sparkfun NEO M8U) into your SCK then altitude adjustment can be made automatically, wherever you take the device.
The SCK system is designed as both a hardware and a software project. You have complete access to the firmware to make any changes you like. This is quite unlike any packaged weather station you might find on the market.
The readings taken by the kit are calibrated and highly accurate, again, quite unlike any you will find on the market.
There are hundreds of different weather stations out in the market place. Lots of people want to manufacture them. I am not sure what is the attraction. The difference with Smart citizen is the focus on (Air, Light, Sound) Pollution, the weather readings inform the pollution readings. Smart Citizen kit takes this a certain distance, but smart citizen station takes this a lot further, with a range of Pollutant gasses being measured, and the station can be further extended, as I am planning to do, by adding Anemometer, Rain Gauge, GPS and solar power. Smart Citizen is unique in the market place, but mine will be one of a kind. :slight_smile:
I’m sorry you are disappointed, I guess you had different expectations. Perhaps read the documentation next time before you start.