[chbot] Wanting real data - How best to mount sensors outside in the elements?

[Mark Atherton]

Single Wire, and analogue temp sensors are already available in sealed 
stainless tubes like 
https://www.trademe.co.nz/Browse/Listing.aspx?id=2635263301

The car water temp sensors also look interesting

Light sensors - hide behind glass/plastic and seal with lots of silicone 
adhesive.

Humidity - no idea. Maybe plug them into high quality gold connectors, 
put the whole mess in a ventilated rain-proof enclosure, and plan to 
change them every year ?

There is probably quite an adventure just finding the correct, low acid 
silicone adhesive...

Water and moisture get into everything eventually. Desiccants help. O 
rings help. Sealed compression fittings help. UV stabilised outer cable 
insulation help.

Lightning strikes do not help, and are just plain difficult to design for.

Robin Gilks has been known to put stuff outside, so will hopefully have 
some wisdom.

---

Other concerns are about carrying signal-levels long distances and 
associated concerns with noise. Shielded cable can help in the right 
system, but can also hinder because of associated capacitance.

A keen approach would be to run RS485 + power to the sensor assembly, 
and build a complete acquisition system in a water-tight enclosure. This 
can be quite some distance away. This is one way of running industrial 
instrumentation.

The modern way is to use wireless, and the inherent issue with providing 
power. Maybe a Li-Ion cell in a socket, which gets changed occasionally.

Also see 
https://electronics.stackexchange.com/questions/45582/designing-electronics-and-their-enclosures-for-the-outdoors

HTH

-Mark




On 28/05/2020 9:14 PM, Andrew Sands wrote:
 > Hey all list dwellers,
 >
 > I'm looking for advise, suggestions and general pointers to what 
other have done in order to get various types of sensors working out in 
the real world - that is beyond the bench.
 >
 > What sensors perform better / marginal, what methods provide the best 
mechanical / environmental protection.
 >
 > Where should I position say an outdoors temperature sensor?
 >
 > Mostly I'm after less of the theory and more of the I tried this but 
it mutated a spider which ate my cat kind of thing. So don't do that.
 >
 > Thanks for reading, stay safe. Wash your hands.
 >
 > Regards,
 > Andrew
 >
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