Uploaded November 2024 | Updated September 2026, 1 week ago

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A couple of simple and safe circuits for gauging water level, that you can build in 10 minutes at a strikingly cheap cost.
Unlike the #waterlevelsensor I've made years ago (link: youtu.be/Z-1X4IoChiY) that was based on capacitive sensing, these ones are based on conductivity. This characteristic allows a much simpler circuit that, at its basics, is limited to some transistors, resistors and capacitors.
The first circuit is designed to provide an analog output to hook a voltmeter or the analog input of a microcontroller. The other one provides multiple ON/OFF outputs suitable to be used with a PLC or with an Arduino.
These sensors are not ratiometric, instead they are discrete steps and the analog output (which requires an #operationalamplifier LM358) just sports these discrete steps as stepped voltage levels.
Conductive water sensing requires care to avoid excessive current that may cause troubles at the electrodes, and the risk of leakage currents toward external elements, including other unintended circuits or equipment.
These circuit mitigate this risk by the mean of relatively medium-high value resistors. Also, as the name imply, conductive sensing requires a conductive medium. Pure water is not conductive (enough) so some ions or salts need to be dissolved in it to make it to work.

Full series of #Electronics: youtube.com/playlist?list=PLwbCeSU2Kq_zORt4un2iQ3JUYxzWF3cTJ

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