Electronics > Beginners
Kindergarten level question here about short circuit protection
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DavidHBurgess:
I'm very new to circuit design, and I'm basically following an "instructable" about how to build a water sensor that will text and email updates.  Every thing is very straight forward.  (Uses an nodemcu ESP8266 processor and a funduino water sensor, and three wires.  3.3v, GND, and A0.)  My issue is that my application may have the water sensor completely submerged  (just the sensor, the processor will be high and dry).  I imagine if that happens then the wire to the 3.3v and GND will be effectively shorted by the rising water.  My guess is that having the 3.3v and GND directly connected would be a bad thing.  I'm just not sure what to do about it.  I would think dealing with this type of thing if very basic, but it all new to me.

Thank you in advance for any assistance you can provide!
Manx:
The problem wouldn't really be shorting anything -- resistance is too big (you can try with ohmmeter leads in a glass of water or your mouth ;) ). Problem will be with corrosion (electrochemical effects). So I'd recommend hot snot or some adhesive-lined heat shrink to make the sensor's electronics and connectors waterproof.
atmfjstc:
I don't think there is an "easy" way of fixing this if the sensor is not designed to be fully submerged to begin with. In theory you could seal the top part of the sensor with some substance (see potting, conformal coating) but this isn't trivial for a beginner. Or, you could attach some sort of makeshift float to the sensor such that the top part always stays above the water.
Old Printer:
I Googled the Fundino sensor and it does not look like it was designed to be completely submerged. Since it is a pretty inexpensive component I would try encapsulating the "top" portion that has the components exposed with something like a good slow dry epoxy. Before that I would cut off the Dupont connectors and direct solder the connections. From the looks of the board I don't think water on the components will damage them, but might affect the readings a bit since it is analog.
David Cutcher CEG:
From the answers so far, I get the impression that you have chosen the wrong circuit for your application.
I understand that you might not want to say too much, but . . . we need more info.
You are trying to build a sensor. Your Input.
Be specific, when it happens.

* what physically happens
* do you want to sense incremental change (continuous), or just a "one shot?"
* and what type of signal do you want as an output to your system. Wanting to Help
David Cutcher "Certified Evil Genius"
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