mirith:
mart256:
mirith:
mart256:
I would use an Optocoupler. Check the schematic.I wouldn't, since your voltages are going to be sensitive. Reading water like that is a bit odd. You definitely can do it, but the resistances you measure might end up being very different, since the minerals dissolved in the water will affect everything greatly so you could be trying to look for anything between 10s of Megaohms to 100 Ohms. Putting the wires close together (1cm or less maybe?) will help. Make sure to use Tap water to test, since pure water is non-conductive.
When I designed the circuit I was thinking about placing the wires very close together. You are right, if the are far from each other the resistance may be high enough to avoid the optical transistor to be switched.
It really depends how dirty the water is.
Agreed, 'pure water' is a good insulator so that actual resistance of the water in your basement while not 'pure' would tend to have highly variable resistance and the input led of an opto takes several milliamps of current to conduct and with just using a 5 vdc voltage source I would think that it would be a very unreliable method to depend on. There should be several circuits on the web to show decent circuits of the proper sensitivity for your use.