100500th automatic irrigation for plants. Part 2: Sensors and Electronics

In the introductory part of the story, we briefly talked about the general development of the system. In this part, a more detailed story about the measuring technique, which I had a chance to get acquainted with during the development of the project, electronics and, of course, about falling into the mud with your face.

Water level

First there was a discrete sensor made of two stainless steel plates.

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Another case is related to acid. There was nitric acid, about 35% concentration, connected to the dispenser. On the KDPV, from the first part, you can see how the standard light cream hoses of the dispensers pass through the black connectors into brown (sometimes black) PVC. This was the case. As it turned out (let the chemists forgive me), this absolutely should not be done. The PVC hardened in a matter of days, the connectors turned into snot-powder, the system leaked (it's good that emergency drainage was available). Now only the hoses recommended by the manufacturer for these acids, with the removal / replacement procedure. And dilute acids in water.