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It’s a wild world out there, full of curious stuff. And we’re here to get to the bottom of things with the might power of the Internet.
“A small cover on the sidewalk with a metal pattern, foot for scale”
It’s a rain and frost/ice detector. A small current is on the 2 metallic circles, they are not touching and are isolated against each other. When raindrops connect the 2 metals, the small current is amplified or switched, so it can trigger a pump or close windows that are fully open at that time and rain or snow won’t damage things.
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